Chap1 Parking 1to46 En

FOAM

GLAS®

Use of FOAMGLAS®

cellular glass insulation in new build and refurbishment of

roof-top car parks and service decks - THE RESULT FROM LONG-TERM EXPERIENCE

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� REFERENCES

� PLANNING AND DESIGN

� UNDERGROUND CAR PARKS

- Protection of the concrete against condensation

and stresses due to movement

� HELICOPTER LANDING PADS

+ SURFACES FOR HEAVY GOODS

TRAFFIC

� PAVING SLAB SYSTEMS ON

SPACER PADS

- for roof-top car parks and terrace roofs

� PAVERS IN A BED OF FINE GRAVEL

� MASTIC ASPHALT, ASPHALT HOT-MIX

+ GROUTING ASPHALT PAVEMENTS

BUILDING SYSTEMS WITH FOAMGLAS®

� in-situ CONCRETE PAVEMENTS

- with and without mastic asphalt wearing course

� DURABLE CONSTRUCTION

AS PLANNING PRINCIPLE

This manual on parking and service decks is the result from many years

of experience in the construction and repair of roof-top car parks and

decks above insulated rooms and other thermally insulated traffic areas

subject to heavy loads.

The book is intended to be a guide for owners, architects and engineers,

providing information on all types of different FOAMGLAS®

parking

systems that have been built throughout Europe. It aims to ensure that the

right decisions are made when it comes to the proper, long-term planning

and installation of these structures.

When carrying out renovation work, Pittsburgh Corning regularly comes

across damage reports and recurrent defects, and so we would like to

pass this experience on to you and offer professional solutions that

represent a step towards improved building quality and longer service life.

Safe, durable and largely maintenance-free FOAMGLAS®

system solutions

(insulation/waterproofing/wearing courses) are essential.

Waterproofing probems in particular are amongst the most expensive

defects found in buildings today, and this is undoubtedly true for vehicle-

accessed thermally insulated structures.

Additional planning, installation guidelines and technical specifications,

based on our experience of various types and specifications, can be

obtained from the Pittsburgh Corning subsidiaries given at the end of this

document. Pittsburgh Corning’s trained team of specialist advisers is

always on hand to support you in planning and preparing calls to tenders

and to answer any questions relating to the physical requirements for the

building and to calculate the thermal insulation.

Useful information needed for planning, including online calculations,

is provided on our websites.

Your innovative insulation partner

PITTSBURGH CORNING EUROPE

FOAM

GLAS Insulatio

nS

yste

ms

®

ROOF-TOP CAR PARKS

PARKING DECKS

SERVICE DECKS

FOAMGLAS®

Contents

Why FOAMGLAS® thermal insulation for roof-top car parks and service decks? p. 2FOAMGLAS® Compact Roof - durable, high-performing, economical ... p. 4

1. Parking spaces as a value-added service p. 5

2. Durable construction as a planning principle p. 6

3. Types and functions of parking and service decks p. 83.1 Mechanical stress p. 93.2 Thermal insulation p. 233.3 Design of falls p. 363.4 Load-bearing capacity p. 383.5 Fire safety p. 403.6 Chemical and biological factors p. 413.7 Maintenance and simple repair procedures p. 42

4. Design of wearing slabs p. 43

5. Different types of thermally insulated roof-top car parks + service decks p. 47

Bearing and wearing courses p. 505.1 In-situ concrete pavements, with and without mastic asphalt wearing course p. 61

- conventional reinforcement or steel-fibre-reinforced concrete

5.2 Mastic asphalt, asphalt hot-mix and grouting asphalt pavements p. 1415.2.1 Mastic asphalt p. 1445.2.2 Asphalt hot mix p. 1595.2.3 Grouting asphalt pavement p. 164

5.3 Pavers in a bed of fine gravel p. 1855.4 Paving slab systems on spacer pads for roof-top car parks and terrace roofs p. 2115.5 Helicopter landing pads and surfaces for heavy goods traffic p. 225

6. Underground car parks p. 235

7. Planning and design p. 251

8. References p. 255

1

2

1. Safety

Because of the level of safety they offer regarding physical properties,FOAMGLAS® system solutions for thermally insulated roof-top car parks andservice decks are of interest for both planners and owners . The double safetyis the result of the waterproof, compact build-upwith no moisture migrationand the high compressive strength under static and dynamic loads.

2. Physical requirements for buildings

- No moisture penetration- No absorption of moisture by diffusion- No capillary attraction.Vehicle-accessed areas are structures which need a correct risk evaluation inorder to take adequate constructive measures.With fully bonded FOAMGLAS® slabs according to the Compact Roof system, a 3-dimensional water- and vapour-proof build-up is created, allowing no moisture migration.

3. Design

In practice FOAMGLAS® forms, a deformation-free substrate with excellentbearing capacity for various permissible loadings. This means that the calculation and planning of wearing slabs is easier and can be optimised.

Why is this publication needed?This comprehensive guide documents the use of FOAMGLAS® insulation on parking decks, roof-top car parks and service decks and reflects our internationalexperience. It covers a wide range of possible wearing courses and provides succinct explanations.For the building trade, traffic accessed constructions and slabs must be carefullyplanned and can only be installed by specialist companies.The proposed car park systems should be planned and undertaken by a specialistcontractor.The present manual on thermally insulated roof-top car parks and service decksdescribes our experience and know-how regarding the use of FOAMGLAS® in thisapplication throughout Europe.

Why FOAMGLAS® thermal insulation for roof-top car parks and service decks?

Note on liability

Recommendations about the methods, use of materials and construction details are given as a service to designers and contractors.These are based on the long experience of Pittsburgh Corning with the use of FOAMGLAS® in this field and the properties of the products which are known to Pittsburgh Corning. The detail drawings included are meant only to illustrate various possible applicationsand should not be taken as a basis for design.

Since Pittsburgh Corning is a materials supplier for FOAMGLAS®, FOAMGLAS® T4, FOAMGLAS® T4-040, FOAMGLAS® S3, FOAMGLAS® F, FOAMGLAS® FLOOR BOARD, FOAMGLAS® FLOOR BOARD F and FOAMGLAS® READY BOARD and exercises no con-trol over the installation of the building materials, no responsibility is accepted for such drawings, recommendations or calculations. In particular, no responsibility is accepted by Pittsburgh Corning for the systems in which FOAMGLAS® is used or the method of appli-cation by which it is installed. The legal obligations of Pittsburgh Corning in respect of any sale of FOAMGLAS® products shall be deter-mined solely by the terms of the respective sales contract.

3FOAMGLAS®

“Do it once, but get it right from the start!”

This advice applies for flat roofs in general and is even more relevant for flat roofs with wearing surfaces such as roof terraces, green roofs,

or the vehicle-accessed roofs that are discussed in this manual.

We hope that this reference book will act as your guide and prove to be asource of inspiration for the reliable planning and execution of vehicle-accessed, thermally insulated roofs. Pittsburgh Corning offers extensive technical support and consultancy for specifiers, including guidance on insulation practice and detailed product information for parking roof applications on specific projects.

Why choose the FOAMGLAS® Compact Roof for roof-top car parks and service decks?

■ Because FOAMGLAS® is an incompressible and creep free insulation layer, and it is precisely this rigid layer that allows wearing courses of differenttypes to be designed and dimensioned in a streamlined, economical way.

■ Because the durable FOAMGLAS® Compact Roof, which is resistant to water-infiltration, - can meet all the physical requirements for buildings on

a long-term basis,- prevents the risk of moisture penetration into the insulation/

waterproofing build-up and thus- prevents expensive, premature refurbishments, and, last but not least,- ensures that the kind of damage shown later in this document

will become a thing of the past.

4

FOAMGLAS® Compact Roof provides durable, high performing and economical solutions for thermally insulated roof-top car parks and service decks

Reliable, economical

technology requires

experience and innovation.

FOAMGLAS® thermal

insulation systems for

parking and service decks

are constantly being

improved and can offer

some versatile solutions.

FOAMGLAS® products can

withstand any loads,

from cars to HGV’s and

helicopters.

FOAMGLAS® is a closed-cell insulation material made from cellular glass, which is suited for all building components.

Over 50 years’ experience with the FOAMGLAS® Compact Roof in combination with wearing courses have resulted in the develop-ment of high-performing system solutions which offer constantthermal insulation, durability and a wide range of design options.

The Compact Roof system is characterized by the following properties:

� no moisture migration because of the full bonding, i.e. fullyadhered and with filled joints, of the insulation to the substrateand of the waterproofing,

� consistent thermal insulation that is not adversely affected by moisture absorption,

� bearing capacity and stability without deformation of the thermal insulation slabs, and so no failure of the wearing surfaces as a result of unexpected tensile bending stresses.

Constant thermal insulation and durability are the preconditions for economic viability and sustainability in building – precisely the qualities that owners are looking for!

Concrete slab surfaces and

pavements.

Mastic asphalt, hot-mix installation

and rolled asphalt coverings.

Grouting asphalt pavements.

A reliable system,

with the benefits of :

� safety, toughness

� versatility

� durability for

the structure

with normal maintenance,

even under extreme loads.

Choice of wearing surfaces:

5FOAMGLAS®

1. Parking spaces as a value-added service Safety and user-friendly design are obvious requirements

Greater mobility and the need for individual transport are what charac-terize the spirit of the times as far as today’s drivers are concerned.

These trends are countered by THE OBSTACLES:Traffic chaos and jams, especially in the densely populated inner city areas.Traffic problems are increasingly taking on a different dimension becausemore and more ground is being built on, leaving hardly any room for carparks, green spaces and playgrounds. It is a fact that traffic density is alsoincreasing “at rest”, i.e. in parking areas. However serious the intentions ofthe car manufacturers are in their efforts to produce smaller vehicles, thisdoes not solve the greater problem of parking.

THE CONSEQUENCE: In private, public or commercial building develop-ments, car parks are increasingly being integrated into the building design.Parking spaces, commercial developments and residential areas exist side byside.The parking spaces that are no longer available on the street are nowbeing provided on roof tops, on service decks above insulated undergroundrooms, or in underground car parks. However, where the usage is mixed (atraffic structure plus residential/commercial buildings), the requirement forthermal insulation is a priority. As parking areas are generally large, heat-transmitting border areas of buildings, they should not be ignored when considering, for example, fulfilling the requirements of Energy Saving Regu-lations (e.g. Building Regulations Part L1/L2 in England and Wales / Part J in Scotland).

Naturally, drivers do not associate a change in the type of parking availablewith any restriction on use; instead, they expect availability at all times.Building developers and operators are looking for durability, economic via-bility and safety from these parking developments. The profitability oracceptance of residential developments, office blocks and public buildingsdepends largely on the availability of parking.

THE PRIME OBJECTIVE: “Reliability” in terms of both construction andsubsequent operation or use is the main aim for planners and operators.People need defect-free, easy to maintain highly compatible systems whichbuild on a limited number of functional layers and which are produced usingproven, foolproof building methods.

The needs of drivers, developers and operators, planners and building work-ers must all be taken into consideration. The FOAMGLAS® COMPACTROOF provides planners with a high-quality system that not only meets allfunctional requirements but can also be installed with reduced risks for pre-mature failure and problem-free use in the long-term.

6

2. Durable construction as a planning principle

1) SOURCE: Federal Ministry for Traffic, Building andHousing, “Leitfaden Nachhaltiges Bauen” (Guideline on Sustainable Building). Order by e-mail from: [email protected]

Fig. 1

The cost blocks in the planning, building and usage phase and theopportunity to influence them.SOURCE: Handbuch der kostenbewußten Bauplanung: Ansätze zu einemden Planungs- und Bauprozess begleitenden Kosteninformationssystem[Manual of cost-conscience building planning: Approachesfor a cost information system as planning and building pro-gresses]; Schrift zur Ingenieurökonomie (Paper on EngineeringEconomy), vol. I, Wuppertal, Dt. Consulting Verlag 1976, p.4, fig. 7,Prof. Dr. Karl Heinz Pfarr

The costs aspect very often influences the decision-mak-ing process in the choice of one construction solution oranother.

Basically, it can be said that

the potential for influencing

the running costs of a building is greatest

during the conception or planning stages.

Decisions which have a major effect on costs

are made during the definition of

the planning grid in the start-up phase.

FIGURE 1 from the “Guideline on SustainableBuilding” (page 2) shows how the individual cost cate-gories are distributed throughout the time schedule for thebuilding.

Sustainability must be a priority

in building

Sustainable building aims to minimise the use of ener-gy and resources and reduce the strain on the balance

of nature throughout all the lifecycle stages of buildings(from planning and construction, through use and mainte-nance to demolition).This objective can be achieved in combination withFOAMGLAS® thermal insulation for roof-top car parks andservice decks.The requirements of today’s world are:❖ a reduction in the energy consumption and❖ the planned extension of the service life of products

and building structures.

Users and operators should participate in the planning stage.Buildings are generally used over long periods of time (50to 100 years on average).The time scales for buildings, including roof-top car parksand service decks, that should be worked with in the per-spective of ecological and economic considerations shouldbe measured against this expectation.1)

Build

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Building time Usage time

Building

User

Planning costs Usage costsBuilding costs

increases

decreases

The opportunity for influencing the economic viability

of a building

Usag

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e

7FOAMGLAS®

The FOAMGLAS® Compact Roof is a warm roof withexclusive properties. This single-shell, warm roof systemwith closed-cell, water- and vapour-proof cellular glassinsulation is designed to give maximum benefit. Fullyadhered to the substrate with hot bitumen and filled joints,the FOAMGLAS® insulation layer forms an effectivevapour-barrier. In addition, the high compressive strength,free of settling, is the most important physical propertywhich allows for the safe bedding of concrete wearingslabs or other wearing courses for car parks.

With the Compact Roof build-up, there are no discontinu-ities in the insulation, or thermal bridges. Likewise, thereare no calculated reductions for heat losses from structur-al joints between the deck and vertical components orbreast walls or deductions due to rainwater cooling, ormoisture absorption resulting from diffusion. Conse-quently, the operating costs/energy costs of a buildinginsulated with FOAMGLAS® are lower than they are forother buildings.

The costs involved at the planning, building and usagestages and the potential for influencing these are shown inthe guideline on “Sustainable Building”, mentioned pre-viously.

Because buildings need to have a long service life, thepotential for multiple use/changes of use should also betaken into account.

The vehicle-accessed FOAMGLAS® Compact Roof: a tough construction, versatile in use

In addition, the durability of building materials and compo-nents as a factor in extending the life of the building andreducing the maintenance and replacement expenditureshould also be borne in mind.

A consideration of the trafficked areas and an evalua-

tion of the construction options must take into

account the investment costs, the repair and mainte-

nance expenditure and the costs of demolition.

Ecology

Comparative parameter: Disposal of product

The sustainable building structure: the vehicle-accessed FOAMGLAS® Compact Roof

8

The following chapter discusses the differences andperformance limits of thermally insulated roof-top car

parks, service decks and traffic areas from the point of

view of various stresses and requirements for:

� warm roof constructions using cellular glass insulation and� roof build-ups with extruded polystyrene boards (XPS),

3. Types and functions of parking and service decks

inside and outside the weatherproofing of the building(according to the inverted roof principle).

The investigation includes practical case studies and scientific reports.

Warm roof construction with cellular glass insulation Inverted roof with extruded polystyrene boards (XPS)

� Structural concrete deck� Primer� FOAMGLAS® TAPERED® insulation with cut-to-fall slabs� Weatherproofing� Separating and slip layer� In-situ concrete wearing slab, dimensioned for

the specific project

� Structural concrete deck� Full bonding with hot bitumen and filled joints� FOAMGLAS® TAPERED® insulation with cut-to-fall slabs� Top surface blacked out� Multi-ply bituminous waterproofing or optionally:� Bituminous waterproofing combined with

waterproofing asphalt� Sand bedding, according to regulations� Paving (pavers or interlocking pavers)

� Structural concrete deck� Screed to falls� Primer� Weatherproofing� XPS insul. boards� Separating and slip layer� Sand bedding, according to regulations� Paving (pavers or interlocking pavers)

� Structural concrete deck� Screed to falls� Primer� Weatherproofing� XPS insul. boards� Separating and slip layer� In-situ concrete wearing slab, dimensioned for

the specific project

� In-situ concrete wearing slab � In-situ concrete wearing slab

� Pavement surface with and withoutadditional waterproof asphalt layer

� Pavement surface

(taking into account the latest findingsregarding ∆U and ∆λ supplements in the dimensioning of thermal insulation)

(taking into account the latest findingsregarding ∆U and ∆λ supplements inthe dimensioning of thermal insulation)

9

a) levelling course if required; no vapour-barrier with FOAMGLAS® insulationb) or FOAMGLAS® TAPERED® slabs

3.1 Mechanical stress

FOAMGLAS® Compact Roof

Full bonding between all functional layers:load-bearing for wearing surfaces,

safe substrate for weatherproofing.Integrated Insulation + Weatherproofing System.


In the first place, roof-top car parks and service decks

fulfil a weatherproofing and protective function for

the building. In connection with their use as roof-top

car parks and service decks, however, additional

stresses occur which make them very different from

roofs that are not used in this way.

In addition to being used by cars, thermally insulated service decks are often subject to mixed usage, deliveriesor heavy goods vehicles. Special requirements, such asaccess for ambulances and fire engines, use by refusevehicles or even helicopter landing pads, must also be metin practice.The loading assumptions are made, for instance, in accor-dance with DIN 1055 or DIN 1072.

Moreover, dynamic coefficients (dynamic loads) canincrease the degree of mechanical stress.For this reason, it is important that carriageways andaccess ways on parking decks are specially structured.

FOAMGLAS®

Requirements

Weather-resistant

Resistant to de-icing products

Load distribution

Waterproof

Thermal protection

Water drainage

Load transfer

Protection against moisture

Fire safety

Functional

levels

Wearing slab/surfacewith separating and slip layer

Weatherproofing

Thermal insulation a)

vapour-barrier (and levelling course)

Screed to falls b)

Structural concrete

and


10

a) WHY FOAMGLAS®?

With its deformation-free high compressive strength(depending on product type) of 0.70 - 1.70 N/mm2 (factorystandard as specified in DIN 53421), FOAMGLAS® pos-sesses physical properties that cannot be achieved by anyother range of insulation materials available.

Considering long-term or short-term loading, the designvalues, including safety factors, are:long-term: 0.28 - 0.68 N/mm2, andshort-term: 0.35 - 0.85 N/mm2.

The subsequent thickness of the wearing slab is based onthese compressive strengths, for example, in the case of“in-situ concrete slabs” (see Chapter 4 below,Dimensioning of wearing slabs; dimensioning diagram).The compressive stresses given above should not beexceeded at the transmission surface between the wear-ing slab and the insulation layer.

Compressive strength [N/mm2],

for traffic accessed surfaces, e.g. roof-top car parkCompression

b) TO AVOID RISKS IN CONSTRUCTION

Destruction of wearing layer due to spring effect

and inconsistent support conditions,

in conjunction with springing, flexing and

rocking of the insulation boards

XPS insulation boards are often not able to cope with thestress situations that occur. They are deformed by com-pression depending on the nature and extent of the loadapplied, or show a tendency to reduce in thickness afterinstallation due to thermoplastic material properties, whichmay also be temperature-related. They should conse-quently be avoided.

Long-term compressive strength does not

necessarily mean that there is any safety margin

Normally in design planning, the maximum “long-term”compressive strength of deformable rigid foam insulationmaterials, i.e. materials subject to compression and creep,is taken as the purely theoretical proof of suitability for useby cars. There is often no safety margin.But how reliable are the material limits given, if compres-sion and deformation do not stop under continuous load-ing?

Planners and developers need to evaluate the safety mar-gins, especially as regards the compressive strength ofthe insulation materials used. For this, information on sta-tistics and probability models can also be used.

Corner breaking from in-situ wearing slabs, supported here

on PUR/PIR insulation boards.

11FOAMGLAS®

TIME-BASED PRESSURE DIAGRAM FOR A RANGE OF INSULATION MATERIALS

Duration of loading hours / days

Com

pres

sion

(%

)

In addition to the purely “formal significance” of a generalapproval certificate, responsible planning approaches canbe built on fractile values and safety factors applieddepending on the load situation.

Because of the critical gaps in the definitions provided bythe various approval certificates, planners have to maketheir own decisions in any case.The various official regulations or guidelines laid down byspecialist associations have long since remained unequalto the challenge of providing a structural safety net.

Summary

With thermoplastic insulation materials, deformation doesnot stop. Continued deformation of all the load-bearingelements in a structure, or the vibration behaviour in wear-ing surfaces is the result. Only cellular glass is pressure-resistant without deformation even under extreme load-ing.

SG = Schaumglas = cellular glass insulation

12


Thermal linear expansion

(temperature movement) [mm/m x 100 K]

PUR/PIR

XPS

FOAMGLAS®

Concrete

Deformation / shrinkagea) WHY FOAMGLAS®?

Even in the long term, FOAMGLAS® does not show anydeformation under loading or under the effects of temper-ature or moisture. The insulation can be perfectly laid tobrick pattern and fully adhered to the substrate. Becausethe material is dimensionally stable and because of thetechnique used for installation, i.e. fully bonded with hotbitumen, consistent support conditions are given.This is an important precondition for the load-bearingcapacity and durability of the build-up which distributes theloads.

Full bonding of the FOAMGLAS® slabs to the substrate with

staggered and bitumen filled joints.

Note on thermal linear expansion

FOAMGLAS® cellular glass has almost the same thermallinear expansion as concrete or steel. This physical prop-erty allows for the “power-bonding” with the substrate.PUR / XPS expands by almost ten times as much due tohigh temperature movement.

13FOAMGLAS®


The fault in the system: flexing, springing

and rocking of the insulation

Flexing and warping of insulation materials leads to incon-sistent support conditions and includes bending stressand dynamic deformation in the top layers, plus local col-lapsing of the insulation materials in question. These con-ditions can be seen in the pictures below.

With warping and flexing foam insulation boards, channelscan be formed, which will allow for increased rainwatercooling and have a negative effect on the the thermal insu-lation value.

Warping of the insulation

In addition, with foam insulation boards, warping or curvingcannot be excluded, even during storage on site. This iscaused by the inevitable shrinkage after production andthe greater insulation thicknesses required. The problemswith wearing layers on springy substrates, e.g. in invertedflat roofs, have been discussed, for instance, in damagereports by Professor Günter Zimmermann, presentingnumerous case studies (see Offprint, next column).

Joints between parts of buildings, ramp crossings or park-ing crossovers, narrowed carriageways or bends are areassubject to extreme traffic loads. In these situations warp-ing of the insulation will inevitably lead to structural dam-age in short time.

Warping of XPS insulation boards during construction

caused by temperature changes.

Deformation of XPS insulation boards. The formation of

channels leads to inconsistent support conditions with a

spring effect under loads.

Research report ProfessorGünter Zimmermann:

“...Interlocking pavers arein the trend but there is arisk of deformation, espe-cially when laid on top ofwarping insulation(spring effect) with inade-quate drainage, gapingjoints and unsuitable substrate.”

Offprint from Bau-Zeitung,issue 9/97, pages 8 and 9 -available upon request (in German)!

Design principle of the inverted flat roof

� Structural concrete deck� Screed to fall� Primer � Non-woven filter� Weatherproofing layer + ballast or � XPS insulation boards wearing layer

14

Heavy vehicles and

off-road trucks use

parking decks too.

The proper planning of

the roof structure and a

pressure-resistant

substrate are therefore

important if the

wearing surface is to

remain damage-free

in the long term.

“When there’s a shortageof parking spaces, roof-top car parks turn into off-road race tracks!”

When roof-top car parks weaken from fatigue ...

Formation of dips in an

asphalt wearing layer on

soft insulation.

With small-format, prefabricated parking and roof terrace

systems, the corner fragmentation often spreads until the

entire slab has been destroyed.

Corner fragmentation of in-situ concrete slabs due to a soft

insulation laying course.

Corner fragmentation of

precast flag pavings.

Often, the load limit of wearing slabs/surfaces is reachedbecause of insufficient compressive strength and becausethe compression limit of the insulation materials used hasbeen exceeded.The consequences of this for the wearing layers on top ofthe insulation are illustrated, e.g., in a report issued by theBDA Dakadvies B.V. Institute, refering to the long-termbehaviour of parking and roof terrace systems in prac-tice, using the example of the Autocentury roof-top carpark with paving slabs on spacer pads (Groningen,Zoontjens system):“The parking spaces are intended primarily for the loadingof groceries. If drivers drive (too) rapidly, the paving slabsmove and wobble especially near the parking areas(springy XPS insulation substrate). In the entrance area,the slabs have been pushed into the XPS insulation byvehicle manoeuvring.”

15FOAMGLAS®


Paving slabs on spacer pads, on compressible insulation

(spring effect).

Severe slab displacement over large parts of the roof.Differences in height and corner fragmentation.

Failures caused on paving slabs by overloading and danger-

ous raising of the edges of the drain cover.

Compressible, springy insulation substrate and displacement

of the paving slabs on spacer pads.

The displacement of the paving slabs is so extreme in places

that wooden battens have been inserted as a temporary

emergency measure. The frost damage is clear.

Examples of damage to unreinforced, prefabricated vacuum concrete paving slabs, triggered by mechanicalfailure, or overloading, caused in some cases by deformations of the substrate and/or the effects of frost andexternal condensation.

16

Several paving slabs in a row often break. Fractures were

even found at the spacer pads.


Many XPS insulation boards are compressed and damaged

under paving slabs on spacer pads.

Lack of compressive resistance to point loading, embrittle-

ment and lack of resistance to oils, fuels, rodents and ver-

mine are risks for XPS insulation boards under paving slabs

on spacer pads.

In many cases the poor condition of the XPS insulation boards

can not guarantee constant thermal insulation in the long-term.

Measurement results on the moisture content of XPS insulation

in inverted roof build-ups are given later (see pp. 26 and following).

The types of damage are typical ofcompressible insulation materials andhave been collected from a large number of projects.

The damaged surface of extrudedpolystyrene insulation drasticallyreduces resistance to diffusion. The consequence of this is far greatersensitivity to frost or progressive permeation of moisture throughout the period of use.This ultimately means the loss of thermal insulation capacity.

The database and the assessment ofthe measurements, including moisture content, show significant values which will lead to a critical evaluation of the product foruse in roof-top car parks, service decksand other traffic areas, no matter what type of covering is applied.

17FOAMGLAS®

Limits of use for extruded polystyrene boards

The approval certificate issued, for example, to DOWDeutschland [on 12.9.2000, 3.1.3 Traffic Loads], provesthe point, by defining the limits on the use of XPS insula-tion boards. “With the corresponding loading and work-manship (...) inverted roofs may be driven over by cars orsimilar powered vehicles up to a permitted total weight of2.5 t”.

Pavement deformation on an XPS insulation layer and drifting of thesand fill resulting from the inadequate support of a compressible insu-lation (spring effect). Some of the joint filling no longer exists. Building:Ansbach department store, repaired with FOAMGLAS® Compact Roof.

Spreading of the pavement on loose laid XPS insulation

boards in an inverted flat roof.

Spreading and sinking of paving stones. The sand fill has

been lost in many areas.

Pavement displacement, rutting

Gaping joints between paving stones. The horizontal shear

forces are so great that concrete pavers have cracked

through in the middle in places. The horizontal gaps here are

up to 90 mm wide.

Behaviour of interlocking paver

on compressible/flexible substrates

When interlocking pavers spread, the zig-zag edge supportthat the pavers provide for each other is lost.The consequences: The interpavers incline, the pavementshifts and there is point loading on the insulation/water-proofing courses underneath, ultimately leading to totaldestruction of the wearing course and loss of parkingspaces.

18

Totally destroyed: jointing sand and laying material have run

out and completely blocked the drain.

Collapse of drain cover. In many cases, gratings are high

points in damaged roofs which must be driven around to

avoid damage to the tyres and the vehicle itself.

Shear forces from braking and accelerating in the area of theaccess ramp and wheels turning on the spot in the parkingareas are the cause of the pavement displacement.

Paving deformation on an inverted roof.

Height differences in the XPS insulation boards, affect the

wearing course, as can be seen above.

The wearing course is very warped over the entire surface.


19FOAMGLAS®

No matter which type of pavement block is laid on springy

XPS insulation boards, the problem of spreading of the

pavers with loss of jointing and laying material is frequently

encountered.

Damage at Laborie-Galerie, Paderborn (G).

Damage.

Damage, Kvickly (S).

Research report ProfessorGünter Zimmermann:“...Interlocking pavers arein the trend but there is arisk of deformation, espe-cially when laid on top ofwarping insulation (spring

effect) and with inadequatedrainage, gaping joints andunsuitable substrate.”

Offprint from Bau-Zeitung,

issue 9/97, pages 8 and 9 -

available upon request

(in German)!

20

Holes and cracks in wearing surfaces


Jawoll discount supermarket in Salzgitter: serious damage in the wearing sur-

face laid on XPS insulation boards. Repeated repairs to the wearing surface

were unable to deal with the problem. When the roof was opened up, considerable

damage to the insulation foam skin was found. During the total refurbishment that

was necessary, it was found that the insulation slabs had absorbed over 30% water

by volume; this meant that the original thermal insulation had been practically lost.

This roof-top car park was repaired using FOAMGLAS® cellular glass insulation.

The refurbishment project is described in detail in Chapter 5.1.

Repair using FOAMGLAS®-thermal insulation

21FOAMGLAS®

Roof-top car park on a shopping centre in Hamburg Rahlstedt. In thisroof, problems had been caused by the concrete/plastic foam sandwichpanels. 3 layers of plastic foils had been laid loose under the panels asa vapour barrier and had led to inconsistent support conditions andspring effect, which had triggered the damage.The roof was refurbished in 1999 using FOAMGLAS® insulation.

Allkauf-Markt in Hagen. The serious warping in the carriageway sur-face due to the unstable XPS insulation layer can clearly be seen by thewavy shape of the side section in front of the gravel strip. Frequentrepairs to the concrete wearing surface were unsuccessful. Finally, theonly remedy was refurbishment using incompressible and deformation-free FOAMGLAS® insulation.

Serious damage in the wearing surface on XPS insulation boards.Because of water infiltration into the build-up and damage to the water-proofing, rainwater is able to penetrate to the load-bearing slab.

Famila Hypermarket. Parking deck, sheltered, with PUR insulation,approx. 2 years old; cracks in the concrete surface are already startingto appear.

22

A German surveyor had to report on the damage appearing in a roof-top car park that had been built as an inverted roof using XPS. His comment:

The one who constructed “blue-eyed” and opted for a “green solution” on renovation ...

. . . now uses FOAMGLAS®.

�

�

23FOAMGLAS®

3.2 Thermal insulation


The need for efficient thermal insulation and

no condensation on outer components

It is obvious that thermal insulation on roof-top car parksand service decks is of vital importance when the effectsof heat-exchanging floor area are considered.The owners’ expectations have to be met, in addition tothe minimum physical requirements for buildings, toensure no condensation occurs in the component crosssection (approx. 4 cm, thermal insulation class 040).In the interest of global energy saving, efficient thermalinsulation should allow a reduction in the annual energyconsumption for heating.The German Energy Saving Regulations (EnEV), 2002,define the primary energy requirement at the systemboundary known as the “building envelope”. That meansthat all components, including the HVAC services and theirefficiency, must be considered in the thermal calculation.

The design principles for the future

can be summarized as follows:

� efficient, constant thermal insulation applied to

the shell of the building,

� air-tightness of outer skin of the building,

� elimination of thermal bridges,

� compact design,

� reduction in heat losses from ventilation

by optimized VAC engineering,

� modern heating systems,

� heating of drinking water,

� ventilation with efficient energy recycling,

� passive use of solar energy.

Air-tight build-up, free from thermal bridges, using

FOAMGLAS® flat slabs or cut-to-fall slabs (FOAMGLAS®

TAPERED®) fully bonded with hot bitumen.

FOAMGLAS® thermal insulation for the roof-top car park on

top of the library at the Emdrupborg Teacher Training

College, Copenhagen (DK).

24

Optimum thermal insulation with FOAMGLAS®

for dense urban developments

Thermally insulated roof-top car park on a residential estate at Rue César Roux, Lausanne (CH). The wearing surface is a

BITUZIM® grouting asphalt pavement.

Thermally insulated roof-top car park on La Rouverai Residence, Lausanne (CH). The wearing surface is a BITUZIM® flexible

pavement, i.e. rolled open-textured asphalt pavement with a cement mortar sludge as liquid binder to penetrate the voids.

25FOAMGLAS®

Deutsche Bundespost, Hamburg. Example of a FOAMGLAS®-

insulated service deck covering basement storeys, designed

to take HGVs.

Use of thermal insulation materials to reduce

thermal stresses on load-bearing structures

(stress insulation)

Thermal insulation materials can also be used to reducethe thermal loading of load-bearing structures.The term “stress insulation” is used when insulation isapplied to prevent heating up and thus linear expansion orcontraction of large structural concrete slabs. These slabsmay be part of a roof or a service deck at ground level andrequire thermal insulation for thermal requirements of thebuilding and to protect the structure.

The following developments are examples ofthe use of FOAMGLAS® for stress insulation:

� Deutsche Bundespost, Hamburg – insulated servicedeck covering basement storeys, approved for HGV use (G.).

� Underground car park, Städtische BühnenDortmund (G).

� Underground car park, Dortmund LabourExchange (G).

� Hansaplatz underground car park, Dortmund (G).� Underground car park for Migros department store

under the pedestrian zone approved for HGVs, Rue de Locarno, in the centre of Perolles (CH).

� C & A underground car park, under a main accessroad, Rue de Romont, Fribourg (CH). The roadstructure was designed for a main street with nor-mal traffic, without any weight limit. It was onlylater that the street was changed over to a pede-strian zone, with delivery traffic at night.

You will find comprehensive information about theinsulation of service decks or the cover slabs overunderground car parks in part 2 of this document,which describes in detail FOAMGLAS® system solu-tions that have been applied to building projects.


UNDERGROUND CAR PARKS :

A cellular glass insulation helps in the battle

against the “dripstone cave” effect.

Insulation of a concrete slab over the underground car park

in the street passage in front of the Migros store in Perolles,

Switzerland.

Underground car park at the C&A store in Fribourg, Rue de

Romont. The concrete slab is covered with FOAMGLAS® cel-

lular glass for stress insulation, and the road-building works

are then carried out.

26

a) WHY FOAMGLAS®?

FOAMGLAS® insulating products meet the standards forreliable thermal insulation in the thermal conductivitygroups 040, 045 and 050. The relevant thermal insulationvalue is provided for the entire working life of the building,without moisture absorption or ageing.


A: Warm roof structure with

FOAMGLAS® TAPERED® slabs and

in-situ concrete wearing surface.

B : Warm roof structure with FOAMGLAS® insulation

and block pavement, with and without

interposed waterproofing asphalt layer.

� Structural concrete deck� Primer� FOAMGLAS® insulation with cut-to-fall slabs,

fully bonded with hot bitumen� Weatherproofing� Separating and slip layer� In-situ concrete wearing slab, dimensioned

for the specific project

� Structural concrete deck� Primer� FOAMGLAS® TAPERED® insulation with cut-to-fall

slabs, fully bonded with hot bitumen� Top surface of insulation blacked out,

hot bitumen coating� Multi-ply bituminous waterproofing; or optionally:� Bituminous waterproofing in combination

with waterproofing asphalt� Pavement bedding according to regulations� Interlocking pavers or suited car park pavers

(PB clay pavers, cobblestones)

IN-SITU CONCRETE: Roof-top car park, both open and

covered, at Migros Bulle SA, Fribourg, Switzerland.

PB CLAY PAVERS AND COBBLESTONES IN SANDBED: Hotel

and restaurant in Wehrsdorf, Germany - roof-top car park.

With a compact installation procedure, i.e. fully bonded inhot bitumen with filled joints, all thermal bridges or airleaks are excluded through the design.

A B

27FOAMGLAS®


Insulation materials that lose their thermal insulationcapacity over years of use as a result of moisture

absorption, to the extent that they are damaged and needreplacement, are not suitable and do not meet the expec-tations of owners.

C : Inverted flat roof with in-situ concrete wearing

surface, with and without vapour pressure

equalizing layer.

D : Inverted flat roof with

block pavement.

� Structural concrete deck� Screed to falls� Primer� Weatherproofing� XPS insulation boards� Separating and slip layer or optionally:� without vapour pressure equalizing layer, with

min. 15 cm fine chippings for laying� In-situ concrete wearing slab, dimensioned

for the specific project

� Structural concrete deck� Screed to falls� Primer� Weatherproofing� XPS insulation boards� Separating and slip layer� Pavement bedding according to regulations� Block pavement / Interlocking pavers

DAMAGED INVERTED ROOF WITH IN-SITU CONCRETE

WEARING SURFACE: Total refurbishment using the

FOAMGLAS® Compact Roof system.

DAMAGED INVERTED ROOF WITH INTERLOCKING PAVERS:

Total refurbishment using the FOAMGLAS® Compact Roof

system.

These insulation materials are often laid in the roof outsidethe building’s weatherproofing and are thus exposed tothe elements.This design principle is called the inverted roof. Here, theXPS insulation boards are installed above the building’sweatherproofing and are covered by the wearing surface.

C D

(taking into account the latest findingsregarding ∆U and ∆λ supplements in thedimensioning of thermal insulation)

(taking into account the latest findingsregarding ∆U and ∆λ supplements inthe dimensioning of thermal insulation)

28

Seriously damp state of an XPS insulating layer and spread-

ing of the interlocking pavers.


Moisture absorption through diffusion

* as attested by various expert reports andfield studies

Resistance to vapour transmission [µ]

Damage caused at PTT Ouchy, Lausanne. The original roof

build-up with an in-situ concrete slab was completely satu-

rated; consequently, the parking area and floors beneath

were unusable for several months.

The roof was refurbished with FOAMGLAS® S3 insulation

slabs and a “Bituzim®” grouting asphalt pavement as the

wearing surface.

Adverse effect on thermal insulation caused by

moisture absorption of XPS insulation boards

Wearing surfaces do not actually have a reliable “capacityto remove or drain away water”. With all types of wearing/surface designs, water penetrates under the wearing sur-face to a greater, or lesser extent and thus via the joints ofthe boards under the insulation. This moisture does notactually dry out, but water vapour does diffuse into theinsulation boards.Water may also penetrate in front of overlapping seams inthe weatherproofing sheets and in deflections and depres-sions in the load-bearing slab. The difference in partialvapour pressure to the external environment starts off thetransport of water vapour into the XPS insulation boards.The film of moisture on the upper side of the XPS insula-tion boards does not allow any significant desorption ofinternal moisture. A progressive increase of moisture is tobe observed and the specified thermal insulation valuedecreases by 50% or more.

infinite ∞

29FOAMGLAS®

In the specialist publication “Feuchteverhalten von Um-kehrdächern mit massiven Deckschichten” [“Moisturebehaviour of inverted roofs with dense covering“] pub-lished by the Fraunhofer-Institut für Bauphysik, the author,Künzel, states:“At an interior temperature of 20°C, conventional insu-lation boards made from extruded polystyrene (e.g.CFC-foamed products) reach a water content ofapprox. 10% vol. after 30 years, whilst CO2-foamedboards become much wetter, at over 17% by vol.because of their lower resistance to water vapourtransmission.Insulation moisture levels of over 20% vol. can occurafter 30 years.”

P.S.: CFC foamed products do not exist in the market now,

but you still find them with roof openings. CFC has now

been replaced with other

blowing agents, HFA,

these have a similar

characteristic in respect

of moisture absorption.

Wat

er c

onte

nt [

%vo

l.]

Thickness of insulation board: 100 mm

Time [years]

Development over time of the forecast average water con-

tent in % vol. of XPS insulation boards in an inverted flat roof

with concrete slab cover.

H.M. Künzel, Fraunhofer-Institut für Bauphysik, Stuttgart, 1996.

Visible wetness of the XPS insulating layer as a result of dif-

fusion processes in an inverted roof with wearing surfaces

(dense coverings).

Areas saturated with water can even be seen on the upper

side of the XPS insulation boards under the filter fabric.

Damaged interlocking paver surface due to springing, flexing

and rocking of XPS insulation substrate.

CO2 foamed

conventional,CFC foamed

H. Künzel, Moisture behaviourof inverted roofs with dense covering,available in English

30


The volume of water per sq.m. insulation was : 13 kg

The same conclusion:

EXPERT REPORT FROM BDA KEURINGS INSTITUTE, describing the Fish Auction House in Urk (NL):“Moisture content 33.5%. The XPS insulatinglayer was wet”.


EXPERT REPORT FROM FRANKEN CONSULT, on the roof-top car park in Ansbach (D):“With samples 80 mm thick, a water content ofUv = 16.7% vol. was determined”.

The surface of the insulation board is sludgy and its

structure is clearly destroyed. This board was floating

in water to a depth of 15 mm. Absorbed water dripped

off when the samples were removed. The increased

weight of the board, indicating that water had clearly

been absorbed, was noticeable.

The report giving an expert evaluation of the failing

parking deck at the Kaufhalle in Ansbach (Germany),

including a survey of the refurbishment works using

FOAMGLAS® thermal insulation is available on request.

MANY EXPERT REPORTS and scientific studies on roofbuild-ups with XPS insulation boards and various drivingsurfaces have recorded symptomatically increased waterabsorption in the insulating layer.The large amount of damage recorded indicates that thisroofing system does not meet the requirements for lastingthermal insulation and load-bearing capacity.

Copies of all studies and reports are available from Pittsburgh Corning.H. Künzel A. Eggenberger

31FOAMGLAS®


EXPERT REPORT AMEND + HINRICHS,Determination of moisture contentProperty to be refurbished: Bildungszenrum Hems-

bach (D), accessible/terraced roof

Moisture content: 27.5% vol., in XPS insula-tion baords, with ship-lapped edges, 8 cm thick

Quotation:“The samples were dried to mass constancy.The average moisture content was 27.5% vol.”

The saturated area can be clearly seen at the point of fracture

because of the dark colouring. Around 30% of the cross-sec-

tion on the top was soaked with water.


Hartwig M. KÜNZEL :“Possibilities for the drying of inverted roof insulationin the summer with different coverings “.Offprint from BAUPHYSIK:

“The results show clearly that water-retaining orrelatively vapour-proof coverings prevent thedrying of the outer surface areas of insulationboards on inverted roofs, in contrast to the con-ventional aggregate ballast ... The moisture conditions at the upper side of theinsulation boards could not be improved evenwith the use of special drainage layers”.

How much does the insulation value of insulation boards deteriorate as a result of water absorption?When the question is asked about the effect of moistureon thermal insulation, various studies have drawn thesame conclusions.For example, EGGENBERGER BAUPHYSIK describes theinfluence of internal moisture on thermal conductivity inthe chart below showing an approximation of moisturedependency.

Approximation of the moisture dependency of the thermal

conductivity of XPS insulation products λsim = λdesign* f (%

vol.) through the function acc. to Hay or acc. to Point. 4.3.

In addition, the linear dependency is also shown. It can clear-

ly be seen that the latter function is not a suitable one since

it gives λ-values that are too positive.

Approximation of thermal conductivity of CO2-foamed XPS with a λ initial value

in the dry state of: 0.038 W/mK

The

rmal

con

duct

ivity

[W

/mK

]

32


With the moisture levels systematically encountered inthermally insulated inverted roof variants for parking decks,an approximate relationship can be assumed, under which,in the area up to 10 % vol.: 1 % moisture by volume corre-sponds to a reduction of thermal insulation capacity ofaround 4%.

Even taking a conservative view, 20% vol. moisture thus leads toa 100-150% deterioration of the thermal insulation value, i.e. 2 to3 times higher than the assumed thermal conductivity at thetime of planning.

If we ask the question about the level of thermal insulationthat is actually effective in the long term, the deteriorationof the values for the thermal conductivity λ must be cor-rected by a supplement value of ∆λ accordingly.Unfortunately, the general approval certificates that havebeen issued, e.g. from the DIBt in the Federal Republic ofGermany, do not yet give due consideration to this aspectand to the results of independent scientific studies.The moisture absorption mechanisms of the largely diffu-sion-blocking covering layers, however, have now beendefined, and require ∆λ supplements in addition to the regulated ∆U supplements (rainwater cooling penalty).

On the basis of the characteristic production values ofDOW and BASF for common CO2-foamed XPS productsused in roof-top car parks, the effective thermal insulationacross the lifetime of the building is relevant.

If we initially consider the moisture absorption processesand their effect on thermal conductivity, with a 10 or 20%vol. moisture level, we obtain the following final figurewhich describes the thermal insulation, for example, after10 and 20 years.

In addition to the moisture absorption processes in theXPS insulation boards caused by diffusion, supplementsfor rainwater cooling must also be taken into account (for-merly ∆k, now ∆U).

The U value, i.e. the thermal transmittance of the roofbuild-up must be corrected by a supplementary value,since cold water removes heat, or heating energy from theupper side of the weatherproofing and thus from the heat-ed building.

The quantity of rainwater to be drained under the insula-tion which cools the roof deck through heat transferdepends considerably on the type and quality of jointing ofthe specific wearing layers.

With joints which are intentionally open, e.g. in the case ofpaving slabs on spacer pads, it is to be assumed thatpractically all precipitation will penetrate under the XPSinsulation boards to the level of the weatherproofing andremove heating energy accordingly.In the case of coverings with interlocking pavers withtight and filled joints, a certain volume of rainwater will bedrained on the top surface and consequently the requiredsupplement ∆U for rainwater cooling is lower. Even with large-format in-situ concrete slabs which havesealed joints between them, it must be assumed that pre-cipitation moisture will penetrate. The joint filling in the relevant sectional division does not create a water-tightsurface nor drain-off all the rainwater into the roof outlets.

Both H.M. KÜNZEL (Moisture behaviour of invertedroofs with dense cover layers, IBP Mitteilung 295 publi-cation) and J.-P. SCHLEE (Thermally insulated roof-topcar parks and service decks, 1998) refer to the necessityof the ∆λ supplement.

J.-P. SCHLEE, table 3, page 90, illustrates the influence ofdifferent wearing surfaces.• For interlocking pavers, because of a reduced rain-

water cooling factor, a ∆U of 0.03 W/m2K is assumed.• In-situ concrete slabs jointed in the area of the sec-

tion division have a rainwater cooling factor of ∆U inthe order of 0.01 W/m2K.

• For precast paving slabs on spacer pads with adrainage coefficient of almost 100%, we can assumethe conditions of the inverted roof with aggregate bal-last, i.e. without dense covering, exposed to the ele-ments and requiring ∆U supplements of 0.05 - 0.19 asrainwater cooling factor, depending on the climaticzone.

Thermal conductivity [λ value]

* reduced λ value in function of moisture absorption** depending on product type

33FOAMGLAS®

According to an approved European draft standard tocome into force (document 777), the following equationprovides the definitive solution for calculation of the neces-sary supplements:

∆U = 0,04 x Ra / Ri x Nd

This obviously makes sense, since, for example, theregional conditions can be taken into account for the dailyprecipitation volumes.

Ra: Thermal resistivity outside the weatherproofing of the building

Ri: Thermal resistivity inside the weatherproofingof the building

Nd: Daily precipitation [mm]

If we assume around 90% of the thermal resistivity abovethe building’s weatherproofing, the rainwater cooling sup-plement for paving slabs on spacer pads is 0.076 W/m2K,rounded up to 0.08 W/m2K (with an average statistical pre-cipitation level in, for example, Germany of 2 mm/day).

Because of the conditions explained previously and theinternationally confirmed findings, a formal reference tothe general approval certificate applied in Germany (where∆U = 0.05 W/m2K) is no longer justifiable.

If we go on to define a thermal insulation objective of 0.30 W/m2K (which is achieved by 12 cm of class 040 insu-lation in the warm roof system), this gives an effectivelyachievable U value of 0.5 W/m2K accordingly for a 12 cmXPS insulation in an inverted roof with closed wearing lay-ers, including the average moisture level occurring in theXPS insulation boards in these types of inverted flat roofsover the course of time (e.g. after 20-30 years).

This means that the thermal insulation of the inverted

roof with 12 cm XPS insulation is 40% less than that of

a warm roof, also with 12 cm thermal insulation in the

λ-class 040.

Put the other way around, the XPS insulation layer in theinverted roof system would have to be increased by 40%,or from 12 to ~17 cm, to achieve the same thermal insu-lation effect after a service life of, for instance, 20 years as would be provided by a warm roof with 12 cm of insu-lation.

34


Required thickness in cm for FOAMGLAS® insulation and CO2-foamed XPS insulation boards

for different levels of thermal insulation and with different wearing surfaces

λA = initial thermal conductivity valueλL = long-term value after approx. 30 years1) Currently valid certificates for inverted roofs in Germany, amongst other countries, are time-limited and do

not provide rules on the necessary supplement values which can be scientifically maintained any longer. Onthe basis of the practical findings now available, the current supplement values can be regarded as out ofdate and thus misleading. The resultant inverted roof insulation thicknesses do not allow the U-value requi-rements defined for planners or specified in standards to be met. The existing time-limited approval certifi-cates are in urgent need of revision.

2) Average moisture content likely after long-term use (i.a. according to H.M. Künzel, Eggenberger, Hector andKrakenberger, etc.).

3) The effectiveness of the vapour pressure equalizing layer in fine gravel is not guaranteed; see [H.M. Künzel,1997]. According to the latest practical research, from Scandinavia for example, vapour pressure equalizinglayers of this type are no longer considered effective. This means that the moisture content in the XPS insu-lating layer which is actually likely in the long term should be increased from 10 to 16% vol. and the resultantinsulation thicknesses should be assumed to be similar to “Interlocking pavers on fine chippings”.

4) See, i.a.”Bauschädensammlung” (descriptions of building damage) collected by G. Zimmermann.5) See W. Zapke, 19986) A. Nielsen, E. Paulsen: Moisture content for ventilated prefab paving slabs on support pads, Norwegian

Building Research.7) For environmental reasons: XPS is CO2 foamed, i.e. cellular gas is air.8) Resultant average thermal conductivity (design value) for calculation of the insulation thicknesses listed.

35FOAMGLAS®

Ponding due to deflections of the slab and insufficient fall.

Failure of the drainage gutter.

Water ponds on a roof-top car park.

DESIGN RECOMMENDATIONS FOR

PARKING DECKS AND ROOF-TOP CAR PARKS:� A sufficient fall.� Few layers.� Structural measures to prevent water

infiltration.� Number of joints: as few as possible, but as

many as necessary.� Joints to be made as simply as possible.� Parking decks in concrete with special proper-

ties according to DIN 1045 (concrete imperme-able to water, high resistance to frost and de-icing agents).

� Surface sealing or coating to reduce dust andto prevent the penetration of chlorides into theconcrete.

Wet wall underneath a damaged roof-top car park.

Reasons for increased

water absorption?

Experience has shown that several factors in parallel leadto increased moisture values in XPS insulation boards. Thefollowing general conditions can be regarded as contribu-tory factors:a) Water film or 100% relative humidity below and above

the insulation.b) Vapour barrier effect of the covering or formation of a

water-retaining layer of fine particles and particles ofdirt on the insulation due to sedimentation processes.

c) Damage to the skin of the foam by direct contact witha fine gravel layer.

d) Water ponding under the insulation, in front of overlapsin the weatherproofing sheets or in deflections anddepressions in the load-bearing slab structure.

(Source: Report by Amend + Hinrichs, 3.2.2000)

36

3.3 Design of falls

Incorporation of a fall

yes

no

yes

FOAMGLAS® TAPERED® cut-to-fall slabs

Project: Astra Zeneca, Kv. Lycktan, Södertälje (S). Planner: Scandiaconsult, StockholmContractors: Skanska, Stockholm + Skanska AsfaltThermal insulation: FOAMGLAS® TAPERED® cut-to-fall slabs

120 - 370 mm; 3.000 m2.

The recommendation is therefore:

Fall and insulation in one.

3.3 Design of falls

A sufficient fall should be created (according to theGuideline on Flat Roofs, >2% or to special weatherproof-ing standards, e.g. DIN 18195 in Germany) in order toensure that surface water is drained off and no water maypond on the wearing surface. A fall is therefore both desirable and essential for reliableuse and operation. However, a fall leads to increasing connection heights atthe edge of the roof, or to other components and storeys.

In addition to these purely geometrical considerations, theincorporation of a fall also has a considerable effect on thestructural loading and the sequence of the building work.Additional fall layers, e.g. screeds to fall, increase the load-ing and entail longer construction periods. Obviously, ascreed to fall of this type will also involve extra costs.

a) WHY FOAMGLAS® ?

The defined level for the water drainage can be createdusing FOAMGLAS® TAPERED® insulation.

In addition to shortening the building time and reducingstatic loads, incorporating the fall in the insulation materialcan also improve thermal insulation. This gives the advan-tage of a “streamlined construction” and minimizes thetotal built-up height (for component cross-section, seepage 26).

The reduced final thickness, low built-up height and, con-sequently, smaller proportion of the facade, etc., also low-ers costs with continuous parapet walls.

With FOAMGLAS® TAPERED® slabs, there is no need fora separate screed to fall in several directions, which alsocuts costs.


Thermal insulation materials which require additionalscreed-to-fall concretes to take further layers of the con-struction are not recommended. This would include invert-ed roofs, for example.In the construction of inverted flat roofs with interlockingpavers or in-situ concrete slabs, the general approval cer-tificate Z-22.4-224 dated 12.9.2000 (Germany) requires thefollowing:“... in the weatherproofing level and the layers above

it, a fall of > = 2.5% is necessary”.

This will lead, for example, with a drainage length of 6 m,to additional fall heights of 15 cm in the load-bearing struc-ture. In addition to the structural, i.e. geometric, difficultiesthis would cause, the static loads resulting from the fallare obviously frequently unacceptable.

Our opinion: If the insulation only functions from a 2.5%fall with inverted flat roofs, the entire roof-top car parkdoes not necessarily need to be built on this basis. It isbetter and more economical to use FOAMGLAS®

TAPERED® insulation. The water drainage function canalso be carried out with shallower gradients.

Because of the additional weight loading and the long dry-ing time which will delay building progress by severalweeks to months, labour-intensive, expensive screed tofall concretes are problematic.In addition, screed to fall concretes form a porous,absorbent and water-conducting interposed layer, in com-parison with structural concrete layers. This means that ifthe weatherproofing is damaged, water can spread andpenetrate freely.

37FOAMGLAS®

38

3.4 Load-bearing capacity

3.4 Load-bearing capacity

The forces due to traffic loading are distributed throughthe wearing surface into the insulation layer and then oninto the load-bearing structure.

Beside the fundamental question “is the declared com-pressive strength of the insulation boards sufficient totake the mechanical loads?” (cf. chapter on MechanicalStress), the deformation behaviour of this interposed insu-lation layer is of crucial significance for the total behaviourof the car park build-up and the durability of the wearingsurfaces.

Available - in German - on request from Pittsburgh Corning Europe.

a) WHY FOAMGLAS® ?

Cellular glass is the only thermal insulation material that is,in practical use, incompressible and free from deforma-tion.There is no local deformation of the thermal insulationlayer due to material creep or fatigue and no undesirable“springing” effect. “Creep studies” have confirmed thefact that there is no deformation of FOAMGLAS® insula-tion products under permanent loading.

From the concluding remarks of the study report “Lang-

zeitverhalten von statisch belasteten Wärmedämmun-

gen” [Long-term behaviour of thermal insulationmaterials under static load] by the DepartmentErddammbau und Deponiebau [Earth Embankment andDump Building] of the University of Karlsruhe:“Instead, the measurements indicate that after perma-nent loading over a year or more, only insignificantdeformations are to be expected for FOAMGLAS®, andthese may be considered to be irrelevant in terms ofbuilding requirements.”

For the design principles according to Westergaard, forexample, a modulus of compressibility of 300 or 150MN/m2 (short-term/permanent load) can be assumed inconnection with cellular glass (see also p. 43).

Because of the rigid substrate formed by the insulation,the wearing courses, especially in-situ concrete compres-sion slabs, are supported securely. This results in reducedcompression-bending stresses in the wearing slab fromtraffic loads, which means that less reinforcement is need-ed and the thickness of the slab can be reduced.

WE CAN THUS CONCLUDE:

Because of its high compressive strength, FOAMGLAS®

allows wearing slabs to be thinner and more eco-

nomical.

The rigid, deformation-free FOAMGLAS® substrate

is also of advantage for prefab concrete paving slabs

on spacer pads or interlocking pavers.

An important standard workfor the dimensioning of wearing surfaces and wearing slabs: H. Bangerter, Bemessungs-

tafeln für elastisch auf

Dämmstoffen gebettete

Nutzbeläge und Fahrbahn-

platten unter Lasten

(Dimensioning tables forwearing surfaces and wear-ing slabs subject to loading,laid on elastic support using insulationmaterials). Zurich, 2nd edition, 1997. ISBN3-9520291-0-6


Springing, flexing and rocking of insulation materialsand unevenness of the concrete bearing slab are riskfactors with inverted roofsThermoplastic or plastic insulation materials which show atendency towards deformation, or fatigue under perma-nent loading, or as a result of the introduction of dynamicforces should be regarded critically in terms of buildingpractice. The spring effect, which completely breaks upand destroys the wearing surface is a particular danger.Quotation from BAUSCHADENSBERICHTE [Reports OnBuilding Damage], Prof. Dr. Günter Zimmermann, “Beton-

verbundsteinplaster auf Parkdächern” [Interlocking

pavers on roof-top car parks]:

“The support conditions for the wearing course should berigid. The reason for failure are generally the laying con-ditions of the XPS insulation boards with springing, flex-ing or rocking.”

It is also expressly stated in the certificate for XPS products:“Surfaces on which XPS boards are to be laid must meetthe requirements of DIN 18202 in terms of evenness. Inthe case of vehicle-accessed inverted roofs, the sub-strates must be levelled, if necessary using fillers and lev-elling courses, in such a way that there are no deflectionsor depressions and offer good laying conditions for theinsulation, without springing, flexing or rocking.”

What degree of evenness is specially demanded?

In accordance with DIN 18202, a manufacturer of the XPSproducts in question refers to Table 2, “Evenness toler-ances, Row 4”.This table states that, with measurement points 10 cmapart, the limit value of the reference measurement shallbe 1 mm. With the conditions typically found on a buildingsite, the practical implementation of this requirement canhardly be guaranteed.

From ZIMMERMANN: “If, in an inverted roof, the extrud-ed polystyrene boards are laid across the overlaps of abitumen weatherproofing layer, they have no good sup-port conditions as they do not lie flat. They are then sub-ject to rocking and flexing and this means that the insula-tion board becomes springy.”In addition, the causes of damage are characterised as follows:“Moreover to overlapping joints of bituminous water-proofing membranes, folds in elastomer weatherproofingcan also lead to the riding up of XPS boards at two pointswith the consequence , of flexing, springing and break-upof the paving surface.”

39FOAMGLAS®

Patched weatherproofing in an inverted roof has led to rock-

ing of the XPS insulation. This uneven substrate carries

through to the surface level, causing break-up of interlocking

pavers.

Extremely rough surface of the structural concrete slab. This

was unsuitable for the application of a torched bitumen

sheet, and so damage was also caused in this vehicle-

accessed inverted roof with interlocking pavers. The roof

was refurbished using FOAMGLAS® TAPERED® slabs fol-

lowed by a reinforced in-situ concrete slab.

Similarly, cases are also known in which repairs on weather-proofing layers lead to inevitable flexing and rocking of theXPS products, with the consequences already described.These repairs are due to the vagaries of the building site,if the weatherproofing on the unfinished concrete slab isexposed to mechanical stress before the XPS insulation isapplied. In many cases, local damage cannot be excludedand “patches” are not applied at the same level after-wards.

3.5 Fire safety

Building products and structures are being examinedincreasingly critically by responsible building owners interms of fire protection requirements.Although mineral wearing surfaces generally protect theinsulation materials from above in car parks and servicedecks, fire can still reach the level of flammable productsvia joints, for example. In this zone, melting can incline theinsulating layer to the extent that top layers become dis-torted; in some cases, guidelines on emergency exitroutes can no longer be met. The spread of fire and flam-mable gases (risk of gas phase combustion, smoulderingfire) and the release of toxic gases must be evaluated inconnection with insulation materials.

a) WHY FOAMGLAS®?

Cellular glass is the only insulation product to be com-monly classified in European Class A1.According to national classifications applied to date, theinsulation material is in the fire-resistance rating A1. This means that FOAMGLAS® “does not represent a fuelload for the fire”. Despite the use of hot bitumen forbonding, flame spread cannot propagate via the tight jointsof cellular glass slabs which sufficiently encapsulate theorganic adhesive and shield the roof structure from oxy-gen supply.


Insulation materials that are made from petroleum-derivedpreliminary products and other chemical additives are aless desirable option for use in residential buildings orthose intended for continuous use by many people, bothin ecological terms and also, in particular, from the point ofview of fire safety.

Admittedly, direct effects or the ignition of insulationmaterials are less probable with closed wearing slabs, butthere are car park systems with paving slabs on spacerpads which do not sufficiently protect the insulation mate-rial from the reach of flames.

Fire safety experts increasingly feel that it is a risk to allowflammable materials to be used on major building de-velopments, or those where safety is a priority. A closerexamination of the development and propagation of fireswith build-ups that originally were thought to be safe usingflammable materials has shown that fire risks and uncer-tainties under real fire conditions are actually far greaterthan had been thought.

Fire safety using non-combustible building materials istherefore advisable in all cases.

40

3.5 Fire safety

Fire-resistance rating

according to European Class A1 Temperature limits

Temperature °C * short term

Because FOAMGLAS® is non-combustible and fire resistant

to high temperatures, there is no risk of flame spread with

the torch application of weatherproofing as it exists, for

instance, with flame-retardant insulation materials.

3.6 Chemical and biological factors

The use of car park and service decks inevitably createsdeposits of oil or fuel. Insulation materials that come intocontact with these liquids must be studied in terms oftheir resistance.

a) WHY FOAMGLAS®?

FOAMGLAS® is resistant to chemical and biologicalattacks. Oils, fats, acids and chlorides (road salt) do notaffect the cellular structure.


The question of the resistance of insulation materials tooils and fuels is not satisfactorily answered in the case ofplastic foam products.

Dripping lubricants or fuels can reach the insulation boardsthrough joints in the interlocking paver pavement, openjoints between concrete paving slabs on spacer pads orseparating joints between in-situ concrete slabs or large-size prefab slabs. Particularly in the area of reserved carparking spaces, this type of damage can build up and soft-en the insulation. The result: decomposition and destruc-tion of the insulation with subsequent formation of re-cesses in the wearing surface.

41FOAMGLAS®

3.6 Chemical and biological factors

Resistance to solvents

Oil and fuel leakage from vehicles ... not a problem with the

FOAMGLAS® warm roof design!

Damage oninverted roofs:

Lubricants and fuels onwearing courses with pavingor concrete slabs have nega-tive effects on insulationmaterials not resistant to sol-vents. The roofs and servicedecks were repaired usingFOAMGLAS® insulation.

Destruction of the plastic foam insulation caused by petrol

and oils. Warping of up to 5 cm was found in the pavement.

The extruded foam had collapsed.

3.7 Maintenance and

simple repair procedures

On accessed roofs, damage to the weatherproofing causeseven more serious problems than is found on inaccessibleroofs. If the origins of leakage have to be detected, thewearing courses have to be removed first, before thesearch for the damaged area can start. If there are several layers above the weatherproofing, e.g.with green roofs, the Guideline on Flat Roofs for examplerequires that “no migration of water shall be possible inthe event of leaks”, or that the damaged area shouldbe located without too much difficulties.

The consequences of loss of use and building repairs areunacceptable for roof-top car parks. The “worst case” ofwater in the roof - should be avoided. The alleged advan-tage of the inverted roof system, i.e. easy access to theweatherproofing, is a poor consolation. It is better to avoid damage from the outset and to ensurethermal insulation.

a) WHY FOAMGLAS®?

According to the Guideline on Flat roofs, the FOAMGLAS®

insulation/waterproofing system is an ideal solution.With the compact, fully bonded build-up of all layers, therequirement for limitation of damage is met. Only in theCompact Roof is the continuous waterproofing functionover various layers of the construction carried out. The waterproofing membranes, the bitumen for adheringthe sheets, the hot bonded FOAMGLAS® insulation slabswith bitumen filled, staggered and butt joints and the hotbitumen poured onto the deck form a build-up that iswater- and vapour-proof and excludes water migrationbetween the different layers.

42

3.7 Maintenance and simple repair procedures

No extended water infiltration because of the compact adhesion of alllayers. Easy repair, the renewal of the waterproofing, leaving the insu-lation in place or the exchange and rebonding of individual insulationslabs at a specific position are possible at any time.

Possibility of repair / change of use

yes

no

* only if totally demolished

no


Insulation materials that are not water- and vapour-proofcan absorb and transmit moisture in liquid or vapour form.

The same applies to installation: only full bonding withfilled joints will ensure that water infiltration beneath thewearing surface will not extend into the roof, causingextremely unfavourable conditions for any repairs.

Design of wearing slabs

In contrast to asphalt wearing courses and interlockingpavers, it is possible, with vehicle-accessed large concreteslabs (wearing slabs) to determine proof of the slab load-ing as a function of the substrate - in this case, the insula-tion. The degree of loading of the insulation materials inconnection with in-situ pressure distribution slabs is alsoclearly defined.To determine the thickness of pressure-distributing wear-ing slabs and to determine the pressure on the insulation,the individual load and the associated support area mustbe known (wheel load).

The quality and properties of the insulation materials areimportant for determining the thickness of the wearingslab. In addition to thermal and physical factors, informa-tion must be available on compressive strength and theelastic limit of the insulation materials, so that the wearingslabs can be dimensioned and, ultimately, failure-free useguaranteed.

In the past, the slab thickness was determined using thepressure cone method. With a load application angle of 45-60 degrees (depending on the wearing surface), thevarious test criteria had to be fulfilled.

Today, wearing slabs are calculated on the principle of“subgrade reaction”. This design method considers thesettlement of all functional layers in proportion to the load.It also considers the auxiliary load bearing effect of sur-faces that are situated outside the direct support area ofthe wheels, for example.

The slab rigidity and the modulus of subgrade reaction areimportant factors for the compressive stress on the slaband the insulation or substrate. Calculations are made forindividual slabs which are 25 - 30 times the slab thicknessfor various positions (middle of the slab, edge, corner ofslab).

According to Westergaard’s method of calculation, thedurability of the roof structure is then tested in four ways:1. Compliance with the permitted flexural stress in

state 1 (cross-section not cracked)2. Determining the necessary bending reinforcement

according to DIN 1045 for state 2 (cross-sectioncracked)

3. Compliance with the compressive stress limit forthe insulation material (target pressure).

4. Proof of puncture resistance of the concrete slab.

Depending on the time assumptions (short-term or per-manent), the modulus of subgrade reaction for the entiresystem is determined on the basis of the insulation productdata (modulus of elasticity or modulus of compressibility).

43FOAMGLAS®

4. Design of wearing slabs

La Boursidière roof-top car park, Le Plessis Robinson (Paris, France).

10.000 m2 of FOAMGLAS® TAPERED® slabs in combination with in-situ concrete wearing slab.

Although the dimensioning of wearing slabs is oftenundertaken by specialist engineers, who determine theprecise building-specific marginal conditions with the aidof computers, the “Dimensioning diagram” shown hereis an estimate and an initial guide for the dimensioning,calculation and specification of wearing slabs.

A SAMPLE OBSERVATION assumes vehicles in bridgeclass 9 / 9. For short-term loading (including dynamic coef-ficient γ = 1.4 or permanent load), the necessary wearingslab thickness or the proportion of reinforcement can beread off.The crucial results are printed in bold.

Results read off the dimensioning diagram

44

4. Design of wearing slabs

Material

-

Type of loading

FOAMGLAS® T4, S3

Short termPermanent load

XPS, 40 kg/m3

Short termPermanent load

Required

wearing slab

thickness [cm]

1315

19

17

Reinforcement

required*

kg/cm2

88,5

9,9

9,9

* on average

It can be seen that FOAMGLAS®, unlike the design option“Roof-top car parks with XPS insulation” requires a muchthinner wearing slab and less reinforcement.

Details on the methods of construction and calculationmethods are given in the corresponding specialist litera-ture. As an example, we would refer to the publication byJens Peter Schlee: “Wärmgedämmtes Parkdach,Hofkellerdecke, wärmegedämmte Verkehrsfläche”[Thermally insulated roof-top car parks, service decksabove basement storeys, and other thermally insulat-ed traffic areas], issued by Fraunhofer IRB Verlag. The book is available in German on request via your near-est Pittsburgh Corning office.

Design advantages for

traffic-accessed wearing layers

The design advantages of FOAMGLAS® basically apply toall types of wearing slabs/layers. With pavings, cobbles,large-size concrete slabs and asphalt finishes too, operat-ing reliability and durability are improved by the rigid,incompressible cellular glass substrate.

Interlocking pavers are laid on a bed of approx. 5 cm finechippings/sand (compacted). The important factor for alasting paving pattern is a rigid, compression-resistant sub-strate and proper filling of the joint with sand, whichmeans that the individual interlocking pavers are support-ed along the zig-zag edges against each other when thewheels roll over them. The stress distribution and thecompressive loading into the insulation layer can then becalculated with a load spread of 45 degrees.

In connection with prefabricated concrete paving slabs

on spacer pads, the compressive stress is transmitteddirectly to the insulating layer via the spacer pads. Engineersmust determine whether the wheel load, including dynamiccoefficient, exceeds the maximum compressive stress lim-its for the insulation material.

In general, asphalt wearing courses are made up ofapprox. 2 to 3 cm thick layers (asphalt waterproofing/asphalt wearing surface) above a weatherproofing that issuitable for asphalt works. The bearing capacity of a masticasphalt layer depends largely on the loading time, theambient temperature, or the intensity of sunlight. Depending on the marginal conditions, mastic asphaltallows more or less direct load transmission. If sunlightwill be a factor, the mastic asphalt layer is either protectedby a load-distributing concrete slab, or additional paving.

The following illustration shows the load distribution by the wearing layer onto the insulation

45FOAMGLAS®

SOURCE : J.P. SCHLEE, P. 58

Force diagram of load distribution by the wearing surface:

max. compressive stress on insulation falls from 1 or 2 to 5,

with the wheel load being distributed over a larger area.

This 190-page

specialist book by

Jens-Peter Schlee:

“Thermally insulated

roof-top car parks,

service decks and

other thermally insu-

lated traffic areas”,

for design and

specification can be

obtained from IRB

Verlag, or is available

on request from your

nearest Pittsburgh

Corning office.

46

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