Brochure Internal Wall Insulation System Design Guide March 2010

7/31/2019 Brochure Internal Wall Insulation System Design Guide March 2010

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Internal Wall Insulation SystemDesign Guide

ResidentialReurbishment

March 2010


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Walls 45%

Roof 20%

Ground floor 13%

Windows and doors 9%

Draughts 13%

Where heat is lost from a typical solid wall house

The importance o wall insulation in houses

Buildings account for 40% of our energy

consumption and in houses the majorityof this energy is lost through the walls.

Thereore insulation is one o the most cost

eective improvements that can be made

and there are various insulation options

depending on how the home is constructed.

In general, the walls in the home can be

categorised into two distinct types. Modern

style homes, usually built post-war (1945),

are constructed with cavity walls. Older style

homes are constructed with solid brick walls.

Around a third o the heat is lost in an

un-insulated house with cavity walls, which

account or a large majority o recently

built homes. Occupants can make savings

around 115 per year* and see a return

on investment within a couple o years by

insulating their cavities.

However, solid walls can lose even more

heat than cavity walls. Typically the totalheat loss rom an un-insulated house with

solid external walls account or 45% (see

pie chart). Insulating solid walls can be

more expensive than cavity wall insulation.

However, higher savings can be achieved

through internal or external insulation or

solid walls saving the occupant up to 400

a year* and internal wall insulation oers

a quicker payback than external wall

insulation.


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Contents

The importance o wall insulation in houses...........................................2

Why insulate a solid wall property.......................................................3

Solid wall insulation options................................................................4

The IWI System..................................................................................6

Features and advantages o the

IWI System........................................................................................9

Avoiding dampness within the construction............................................10

Avoiding thermal bridging and

surace condensation..........................................................................11

Separating walls................................................................................12

Insulation continuity at oors................................................................13

Installation o the IWI System...............................................................15

Installation at window and door openings.............................................17

Accommodating fxtures and fttings..................................................... 19

Why insulate a solid wall property?

Over a quarter o the UKs CO2

emissions

are generated by our homes. O theestimated 25 million homes in the UK

approximately 36% have been labelled

as hard to treat, the majority o which

are solid walled properties. Insulating all

the solid wall properties in the UK would

provide signifcant reductions in the amount

o CO2

we emit and would also help to

reduce an occupants uel bills.

Save money on energy bills

Homes losing heat, lose money. A poorly

insulated home will be costing the occupant

signifcantly more in heating bills than a

ully insulated property. Insulation slows the

transer o heat, reducing the amount o

energy consumption in the home - keeping it

warm in winter and cool in summer.

Eradicate uel poverty

50 per cent o solid wall properties are

occupied by people living in uel poverty.

Fuel poverty is linked to multiple deprivation

and unaordable uel prices characterised

by inadequate insulation and inefcient

heating systems. Fuel poverty can be

seriously damaging to peoples quality o

lie and can be particularly uncomortable

or the older generation, children and the

disabled. Britain is said to have the highest

number o avoidable deaths due to winter

cold in Western Europe.

Help save the planet

Fight climate change by reducing CO2

emissions rom solid wall homes. Solid wall

homes will play an essential role in helping

to save the environment, it is estimated that

a properly insulated solid wall home could

save approximatly 2 tonnes o CO2per

year*. This would represent a signifcant

step on the road to making homes carbon

neutral.

Increase a homes valueInsulating a solid wall home properly

can add to a homes market value by

signifcantly improving its Energy Efciency

Rating. In the case o external wall insulation

it can improve the overall aesthetics

and internal wall insulation can improve

the interior dcor and appearance o a

property.

* Energy Saving Trust March 2010


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External wall insulation or

internal wall insulation?Solid walls can be insulated externally or

internally. Each solution has its merits.

External Wall Insulation (EWI)

External wall insulation systems generally

comprise an insulation layer mechanically

or adhesively fxed to the existing wall

and covered with a render coat; or timber

boarding, concrete and clay tiles or metal

cladding can also be applied.

An external insulation system can radicallyalter the appearance o a property (unless

it is already rendered) and planning

permission as well as Building Regulations

compliance may well be required prior

to installation. Special attention will need

to be paid, or instance, to window sills,

rainwater downpipes and gutters, and

eaves. Relocation or changes to the

rooine may be required to accommodate

the thickness o the system. External wall

insulation systems can deliver high levelso thermal perormance, eliminate thermal

bridging and cause minimum disruption to

the occupants o buildings. External wall

insulation systems are usually installed by

specialist installers.

Internal Wall Insulation (IWI)

Internal wall insulation solutions usually

involve the installation o metal or timber

studs with insulation installed between

the studs and then overlaid with a vapour

control layer and plasterboard. Alterna-

tively, a thermal laminate board or rigid

insulation board plus plasterboard can

be mechanically fxed to the walls. These

systems should not be used to isolate or hide

moisture penetration or damp problems in

the existing structure. In accordance with

Building Regulations, solid walls should

prevent moisture ingress arising rom

exposure to rain and snow without moisture

penetrating to the inside and damaging the

building.

Insulating internally improves the thermal

perormance o the wall without aecting

the external appearance o the building.

However, there will be a small reduction in

the internal oor area and the installation

process may cause disruption to theoccupants o the building. Internal wall

insulation can be installed one room at

a time thereby minimising disruption to

occupants and providing exibility during the

reurbishment programme. In a large numbero cases, internal wall insulation could be

the preerred option because it costs less to

install and maintain than external insulation

systems, does not require scaolding during

the installation process, and the existing

appearance o the building is maintained.

Combination Installations

In many instances (especially mid terraced

houses), the optimum solution may be to

install a combination o both external and

internal wall insulation. An EWI system may

suit the back o a house where appearance

is less important or already compromised

by single storey extensions, outriggers, soil

stacks, rainwater downpipes and boiler ues.

The ront o the house can be insulated with

an IWI system, which maintains aesthetic

quality, while also delivering high levels o

thermal perormance and a exible

installation solution.

Solid wall insulation options

Illustration o external

wall insulation


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Solid wall insulation options

Advantages o internal over

external wall insulationSolid external masonry walls can be

upgraded in two ways, either internally or

externally.

Internal insulation is the preerred solution or

upgrading solid masonry walls because:

It costs less to install than external

insulation

It is easier to maintain than external

insulation

No scaolding is required

The external appearance o the building

is maintained so it can be installed in

conservation areas

No specialist skills or equipment are

required to install the insulation

Materials are readily available

It can be installed on a room-by-room,

single aade or whole house basis, as

part o a ull reurbishment plan

Installation is not delayed by bad weather

Thermal comort

An internal wall insulation system enables

comortable room temperatures to be

achieved more quickly than with an external

wall insulation system. Heating time periods

can be reduced, particularly in intermittently

heated buildings such as dwellings.

Taking the opportunity

An ideal opportunity to install internal

insulation on a solid wall is when other

work is already required, e.g. when

existing plaster is crumbling and needs

replacement, when the decorative fnish

is being removed, or when rewiring or

installing central heating, or during total

reurbishment.

The existing wall should be examined

and any remedial work, e.g. the insertion

o a damp proo course or the repair o

overowing guttering, carried out beore the

insulation system is installed. It is important

that the internal insulation system is not usedto hide or isolate damp or wet walls.

Taking advantage o any opportunity to

improve the energy efciency o a dwellingand upgrading un-insulated external walls

provides a number o benefts including:

Reducing CO2 emissions

Reduced uel bills

Increased thermal comort or the

occupiers

Reduced risk o condensation and

mould growth

Reduction o abric damage and

maintenance costs

Illustration o internal

wall insulation


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The system components

The IWI System is a brand new internal insulation system designed or

upgrading existing solid external walls.

It consists o thermally engineered insulated studs and insulation slabs,

which can be combined to provide greater thicknesses o thermal

insulation than achievable by using a single thickness. EcoStuds are

a composite o high perormance extruded polystyrene insulation and

Oriented Strand Board (OSB). The OSB is manuactured rom timber

supplied rom Forest Stewardship Council (FSC) certifed orests.

The IWI System has been designed to simpliy the process o upgrading

solid masonry walls while delivering high levels o thermal perormance.The system can be installed by any competent builder.

System components

EcoStud extruded polystyrene

bonded to Oriented Strand Board

(OSB).

Earthwool EcoBatt water

repellent glass mineral wool slab

Plasterboard fxings Knau

Drywall screws.

Sealant Knau multi purpose

sealant.

Vapour check plasterboard Knau Vapourshield (min 75MN.s/g)

Plasterboard Knau

Moistureshield, Wallboard

or Denseshield.

Fixing to masonry fxings

manuactured in accordance with

BS1210.

Wall plugs universal wall plugs

as manuactured by Fischer or

Rawlplug.

Vapour control layer

Polyethylene membrane with a

minimum vapour resistance o

260MN.s/g.

U-values (W/m2K) for 225mm solid masonry walls*

EcoStud (mm) U-value (W/m2K)

60 0.45

75 0.35

90 0.30

120* 0.26

150* 0.20

* Combination o two studs required toachieve this thickness

The Internal Wall Insulation System


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Thermally engineered EcoStud, extrudedpolystyrene bonded to a 11mm strip oOriented Strand Board (OSB)

Earthwool EcoBatt, water repellent glassmineral wool slab

Separate vapour control layer (min260MN.s/g), i preerred

12.5mm vapour check plasterboard(min 75MN.s/g). Or standardplasterboard with a separate vapourcontrol layer)

Existing solid masonry external wall

Existing plaster fnish (i sound)

Joint sealed with Knau Multi PurposeSealant

Existing solid masonry external wall withexisting plaster

Thermal laminate board lining reveal

EcoStud (jamb stud lines with edge oexisting reveal)

Earthwool EcoBatt between EcoStuds

600mm dimension to centre o adjacentstud to suit

Earthwool EcoBatt

Thickness(mm)

Width(mm)

Length(mm)

Thermal conductivity(W/mK)

Thermal resistance(m2K/W)

60 555 1200 0.036 1.65

75 555 1200 0.033 2.25

90 555 1200 0.033 2.70

EcoStud

Thickness(mm)

Width(mm)

Length(mm)

Thermal conductivity(W/mK)

Thermal resistance(m2K/W)

60 50 2400 n/a 1.72

75 50 2400 n/a 2.22

90 50 2400 n/a 2.72


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Features o IWI System A cost-eective, thermally efcient

solution

Quick and easy to install so rooms are

out o commission or the minimum

period

Can improve the acoustic perormance o

the existing external wall (see page 9)

Finished using a plaster skim coat or

dry lining techniques

No need to remove existing wall fnish,unless un-sound

System can accommodate wall

imperections

Easily adapted around openings such

as windows and doors

Can easily accommodate fxings or

fttings such as radiators, pictures and

shelving

Benets o IWI SystemThe use o EcoStud eliminates the thermal

bridging issue associated with systems

incorporating timber and metal studs.

EcoStuds, with their XPS backing, provide

a high level o thermal resistance, which

is comparable to that o the glass mineral

wool insulation ftted between the studs.

For example, the IWI System is almost

13% more thermally efcient than a timber

stud system o the same thickness.

Compared with other internal insulation

methods, the IWI System has the ollowing

additional advantages:

The system components are unaected

by moisture (should the external wall

become damp ater installation)

A minimum number o lightweight, easy

to handle, components are required

System thickness is comparable to

alternative solutions, but greater

thicknesses can be provided simply

by installing two studs, one on top

o the other.

Airtight solution enables maximum

thermal efciency to be achieved rom

the system

Incorporates highly sustainable glass

mineral wool insulation (see page 9)

The glass mineral wool infll has the

maximum Euroclass A1 fre rating to BS

EN 13501: Part 1.

Thermal perormance

A typical 225mm (nine inch) thick

un-insulated masonry external wall with

dense plaster internally will achieve a

U-value o approximately 2.00W/m2K.

The same wall insulated with the IWI

System, using 75mm thick studs, will

achieve a U-value o at least 0.35W/m2K,

an improvement in thermal perormance o

over 80%.

I a typical three bedroom semi-detached

house were to be upgraded in thismanner, it would reduce the carbon

emissions associated with the house by

approximately 2 tonnes per year.

The tables (on pages 6 and 7) give key

thermal perormance data or the system.

Three stud thicknesses are available, 60,

75 and 90mm, which can be combined to

give a variety o thickness solutions.

Double stud installation

Enhanced thermal perormance can beachieved by installing double layers o

EcoStuds. For instance, a combination

o two 75mm EcoStuds will achieve a

U-value o 0.20W/m2K. Ater securing

EcoStud in accordance with the

installation instructions on pages 15 - 18,

screw fx a second EcoStud to the frst

one. Both EcoStuds should be installed in

the vertical position.

When fxing the second EcoStud itis essential that the screws should be

sufcient to ensure a minimum 38mm

penetration into the frst EcoStud. Care

should be taken to ensure that the two sets

o screws are not installed in coincident

positions.

Earthwool EcoBatts and a vapour check

plasterboard are installed in the same

manner as a single stud application.

Features and advantages o the IWI System


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Other key issues or the IWI System

Sustainability

The IWI System incorporates glass mineral

wool infll insulation, which has the

ollowing sustainability credentials:

It has the maximum A+ rating in the

BRE Green Guide to Specifcation

The basic raw materials are silica

sand, the earths most common mineral

and recycled glass bottles

It can be recycled at the end o the

buildings lie

Manuactured using ECOSE

Technology, a revolutionary, new,

ormaldehyde ree binder technology,

based on rapidly renewable materials

instead o petro-based chemicals.

It reduces embodied energy and

delivers superior environmental

sustainability.

Supakubecompression packaging

saves energy and delivers more

product per pack

Air leakage

Existing dwellings can suer rom excessive

air leakage which, i not treated, can lead

to high energy costs, occupant discomort

rom draughts and external noise, as well

as a reduction in indoor air quality.

To ensure that upgrading o external

walls is as eective as possible, it is

very important to prevent air leakage

through the structure or at least keep it to

an absolute minimum. Air leakage can

be between the interior and exterior, aswell as between dierent elements o the

building envelope.

Air leakage through the masonry wall

occurs through cracks, gaps where there

is poor adhesion between the mortar and

the masonry units, or diusion through

the masonry units themselves. Where the

plaster has been removed and air leakage

through the wall is thought to be excessive,

it should be tackled beore the IWI System

is installed by applying a parging coat to

the inner surace o the wall.

As the insulation component o the IWI

System is in intimate contact with the

plasterboard, air movement behind the

system should not be great. However, to

prevent unwanted air leakage all junctions

with other elements should be well sealed

with particular attention being paid to

the joints between the IWI System and

window rames. In addition, Knau MultiPurpose Sealant should be used to seal

electric sockets against the plasterboard,

as well as all gaps around plumbing

service penetrations. Any large gaps or

penetration through the dry lining system

can be sealed with expanding oam.

Acoustic perormance

Glass mineral wool is inherently good at

absorbing sound and allows sound energy

to be dissipated within the body o the

insulation. This helps to reduce anking

sound transmission across intermediate

oors and also provides sound insulation

rom external noise sources, especially as

the plasterboard lining provides additional

mass to the existing construction.

The airborne sound insulation

perormance o a solid masonry wall, bothto and rom the exterior, can be improved

signifcantly by installing the IWI System;

a typical improvement o up to 5dB could

be expected. However, to maximise the

improvement in acoustic perormance, it

is important that the installed system is as

airtight as possible (see above).

Thermal mass

Generally speaking the amount o

available thermal mass will not besignifcantly reduced by the installation

o an internal wall insulation system in

most house types. Whilst there are no

defnitive rules as to how much thermal

mass is required, a general rule o thumb

is that the surace area o the walls and

oors providing the mass should be at

least six times that o the area o glazing

in the room. The vast majority o existing

houses will have masonry separating and

partition walls, which provide sufcientthermal mass to help stabilise the internal

environment.

Thus, in a typical mid-terraced property,

where the IWI System is only installed on

the glazed elevations, the thermal mass o

the dwelling is not altered signifcantly by

its installation.


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11/2011

Avoiding thermal bridging and surace condensation

Thermal bridging

Thermal bridging occurs when the

continuity o the insulation is broken

causing the inner surace o the wall at

that point to become much cooler than

the surace where the wall is insulated.

This typically occurs at the junction o an

external wall and a separating wall or

oor. Thermal bridging can cause

an increase in heat loss, surace

condensation and mould growth

and can be a particular problem in

terraced houses.

Surace condensation

Simply put, surace condensation occurs

when water vapour in the air cools and

condenses (reverts to liquid orm) when

it comes into contact with a cold surace.

Reducing the amount o water vapour

in the air by extracting moist air rom

kitchens and bathrooms and increasing

the surace temperature will prevent

condensation orming on the internal

surace o solid external walls. The

installation o the IWI System will raise

the surace temperature o the walls to

a level whereby condensation will not

orm under usual maximum humidity

conditions experienced in dwellings. As

can be seen rom Figure 2, the warm

surace temperature o the internal

walls (red colour) remains constant

across the EcoStuds, reducing the risk o

condensation orming on cooler suraces.

Figure 2 Thermal contours through the external wall and IWI System (Image generated usingHEAT 3 sotware)

Cold external surace

Warm internal surace

EcoStud Earthwool Ecobatt

Combustion appliances

It is imperative that ventilation

requirements or gas, oil or coal fred

combustion appliances are not

compromised by the installation o the

IWI System and the system does not

interere with the supply o air to the

appliance.

Recommendations, guidance and

compliance with the Building Regulations

or the ventilation o combustion

appliances can be ound in BuildingRegulations Approved Document J -

Combustion appliances and uel storage

systems.

Flues

Care must be taken to ensure that ues

and ventilation measures or gas, oil or

coal fred combustion appliances are

not blocked or adversely aected by the

installation o the IWI System.

Where a ue penetrates the IWI System,the ue can be completely surrounded

and encased by Earthwool EcoBatt which

is a non combustible glass mineral wool

product. The extruded polystyrene content

o EcoStud should not be subjected to

temperatures in excess o 70C.

The ue can be aced with a

non-combustible board, e.g. plasterboard

or cement based board, prior to the

installation o the IWI System. However,i in doubt regarding the surace

temperature o the ue, contact the

manuacturer o the appliance under

consideration.


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The junction o the external wall and the

separating wall is the location with thegreatest risk o thermal bridging and

surace condensation. As well as insulating

the external wall, the recommendation is to

partially insulate the separating wall using

a 9.50/17.50mm thermal laminate board

(Polyoam Linerboard) or a distance o

400mm back rom the external wall. This

will prevent excessive heat loss and keep

the surace temperature high enough to

avoid the risk o surace condensation.

Neither external wall nor

separating wall insulated(Figure 3a)

Figure 3a shows the eect o the

separating wall bridging the external

wall. The internal corners are in the yellow

contour and are colder than the main

body o the external wall, increasing the

risk o condensation and mould growth

to occur and urther reducing the thermal

perormance o an already poorly

perorming wall.

External wall and separating

wall only insulated on one

side(Figure 3b)

Figure 3b demonstrates the dierence

between insulating and not insulating

at the separating wall junction with

the external wall. The heat loss

through the un-insulated external wall

is approximately 80% greater than that

through the insulated external wall.

External wall and separating

wall insulated on both sides(Figure 3c)

Figure 3c shows that when both the

external wall and separating wall are

insulated, there is an even temperature

distribution at the separating wall junction

with the external wall. As there are no

yellow or green areas at the surace o

the wall, the suraces are kept warm,minimising the risk o condensation and

mould growth.

External wall insulatedseparating wall un-insulated(Figure 3d)

Figure 3d shows the eect o not

insulating at the separating wall junction

there is signifcant additional heat ow

through the junction and potential or

surace condensation and mouldgrowth to occur.

Figure 3 Thermal contours at the

external wall/separating wall junction(Images generated using HEAT 3 sotware)

Separating walls

Figure 3b Party wall insulated onone side

Un-insulated external wall

Un-insulated separating wall

Both external wall andseparating wall insulated

Plan

Figure 3c Party wall insulated onboth sides



Plan

Figure 3a Party wall without insulation

Un-insulated separating wall

Un-insulated external wall

Plan

Figure 3d External wall insulatedeither side o uninsulatedparty wall

External wall insulatedon both sides

Plan


13/2013

Insulation continuity at foors

Suspended timber ground

foorsAn un-insulated suspended timber ground

oor typically accounts or 13% o the

heat loss rom a traditionally constructed

dwelling and should be insulated

whenever possible. Earthwool EcoBatt can

also be used or this application.

The insulation should be the same

depth as the oor joists and ully fll the

available space so as to be in contact

with the underside o the oor deck andtight against the sides o the joists. It

should be supported on netting stapled,

or nailed, to the underside o the joists.

The gap between the last joist and any

walls should also be insulated to maintain

continuity with the IWI System.

I there is a basement or there is a deep

enough sub oor void, the insulation

can be installed rom below and the

netting fxed to the underside o the joists.

Otherwise, the only practical way to

insulate the oor is to lit the oorboards,

orm a cradle by running the netting

over and between the joists and install the

insulation rom above.

To minimise air leakage, the joint between

the oor boarding and the wall should

be sealed using Knau Multi Purpose

Sealant, as should the joint between the

plasterboard and the oor and, fnally,

the skirting board and the oor (Figure 4,page 14). Gaps where radiator pipes and

electric cables penetrate the oorboards

should also be sealed, as should any

gaps between individual tongued and

grooved oorboards.

Where the joints between oorboards are

open, or square edged boards have been

used, a more efcient way o sealing the

oor is to lay hardboard sheets over the

complete oor area.

tIntermediate foors

Insulation continuity

When upgrading external walls, the

insulation layer should be as continuous

as possible across intermediate oors.

Failure to insulate the oor joist zone

results in a major thermal bridge across

the IWI System which signifcantly reduces

the overall thermal perormance o the

external wall.

For example, the eect on the ront

elevation o a typical mid terraced house

insulated with the IWI System would be to

reduce the U-value rom 0.35W/m2K with

the oor zone insulated, to an average o

0.41W/ m2K with an un-insulated oor

zone, equivalent to a 15% increase in

heat loss through the wall.

The loss o thermal perormance can be

avoided by flling the oor zone (i.e. the

ceiling void between the oor boarding

and the ceiling) with Earthwool EcoBattinsulation or a certain distance rom the

external wall, the extent depending on the

direction o the oor joists in relation to

the external wall or separating wall.

Joists parallel with separating wall

Insulation should be installed between

the last joist and the separating wall and

extend along the separating wall by at

least 400mm. Insulation should also be

installed between the joists that are built

into the external wall and extend into

the room by at least 300mm. (Figure 5,

page 14).

As can be seen rom the thermal contours

in Figure 6, page 14, insulating between

the joists o an intermediate oor and

the space between the last joist and the

separating wall (right o diagram) substan-

tially improves thermal perormance,

compared with the un-insulated oor zone

(let o diagram) both through the plainareas o the external wall and through the

separating wall junction.

Joists parallel with external wall

Insulation should be installed between the

last joist and the external wall and within

the frst joist space or the ull length o the

external wall (Figure 7, page 14).

Sealing to prevent air leakage

To ensure that the IWI System achieves its

intended perormance, it is important that

the perimeter joints at the oor and ceiling

are sealed with a continuous bead o

Knau Multi Purpose Sealant.

In particular, the gap between the ooring

and wall and the ceiling and wall should

be sealed, as well as the joint between the

skirting board and the ooring (Figure 8,

page 14). Failure to seal these joints could

result in cold air entering the building

and reducing the thermal and acoustic

perormance o the IWI System.


14/20

Figure 5 Floor zone insulation joistsparallel with separating wall

Insulation betweenjoist and wallextending back400mm

Separating wall

External wall

Plan

Figure 6 Thermal contours with and without oor zone insulated(Images generated using HEAT 3 sotware)

External wall

Un-insulated oor zone

Separating wall

Insulation between joistand wall extendingback 400mm

Insulation flling oorzone at least 300mminto the room

Plan

Figure 7 Floor zone insulation joistsparallel with external wall

Insulation betweenjoist and external wall

External wall

Separating wall

Plan

Figure 8 Detail at intermediate timber oor

Insulation ully fllingceiling void

Seal joint betweenooring and wall withKnau Multi PurposeSealant

Seal joint betweenooring andplasterboard/skirtingboard with KnauMulti Purpose Sealant

Insulation installedbetween last joist and wall

Seal joints with KnauMulti Purpose Sealant

Section

Figure 4 Detail at suspended timberground oor

Insulation supportedon mesh /netting

Seal joint betweenooring and wall withKnau Multi PurposeSealant

Seal joint betweenooring andplasterboard/skirtingboard with KnauMulti Purpose Sealant

Insulation installedbetween last joist andwall

Section

Insulation continuity at foors


15/2015

Installation o the IWI System

Beore installing the IWI System a

comprehensive property surveyshould be carried out to establish

the condition o the building, its

suitability to receive the system

and identiy any remedial work

needed prior to starting the

upgrade process. At this point

a decision can be made as to

whether an internal or external

wall insulation system is most

appropriate or the property under

survey.

1 Where plaster is sound, fx directly

through it, removing existing skirting

boards i required beore fxing the

EcoStuds (Figure 9). I not sound,

remove decayed plaster and, or

greatest airtightness, seal with a

parge coat. EcoStuds are to be

installed with the OSB acing into the

room.

2 Screw fx EcoStuds horizontally to

the oot o the existing wall as set

out in step 4. These studs should be

positioned so that, i the wall is bowed

or not vertical, the verticality o the IWI

System is maintained. The horizontal

studs should also be located to that the

OSB acing can provide a fxing point

or the new skirting board (Figure 10).

3 Screw fx EcoStuds horizontally at the

head o the wall ollowing the same

process as in step 2. Then, fx EcoStuds

vertically between the top and bottom

horizontal EcoStuds as indicated in step

Figure 11

Figure 9

Figure 10

75mm

600mm600mm600mm600mm

75mm

4, spacing them at 600mm horizontal

centres to coincide with plasterboarddimensions. Ensure that the vertical

studs are cut and installed so as to be

in close contact with the horizontal

studs at oor and ceiling level (Figure

11).

Alternatively, where the ceiling line is

irregular, cut EcoStuds to extend rom

the horizontal EcoStud at the oot o

the wall to tight under the ceiling and

fx as described in step 4. Once the

studs are fxed in position, adhesive

fx EcoStud noggins (using Knau Multi

Purpose Sealant) between the studs at

ceiling level to receive plasterboard

fxings. The adhesive sealant should be

applied to the back and both ends o

the noggins. Alternatively, screw fx the

noggins in position.

4 Fix all EcoStuds to the existing wall

using screws and suitable universal

wall plugs. A minimum fxingpenetration o 40mm is required into

the existing masonry wall (excluding

thickness o plaster). Five fxings per

stud are required but the number

can be increased as required, or as

dictated by site conditions. Position the

fxings at 600mm maximum centres

and 75mm rom the end o each stud

as shown below.


16/20

Installation o the IWI System

5 I there are irregularities in the wall

suraces, pack out the EcoStuds usingsuitable materials which are unaected

by moisture. (Figure 12).

6 Friction ft Earthwool EcoBatts (water

repellent glasswool insulation) between

the EcoStuds ensuring the insulation

zone is completely flled. There should

be no gaps between the slabs and they

should be installed so as to be tight to

the plasterboard and ully fll the space

between the studs. (Figure 13). Whereinsulation requires cutting, it should

be cut 5mm wider than the space it is

intended to fll (Figure 14).

7 Once the insulation has been

ftted, screw 12.5mm vapour check

plasterboard to the EcoStuds using

38mm drywall screws, or wood

screws, at nominal 300mm horizontal

and vertical centres, reducing to

200mm centres at corners (Figure 15).Alternatively, fx a separate vapour

control layer ollowed by standard

plasterboard.

Ensure that there is a 3 - 5mm gap

between the plasterboard and the

existing oor to allow space or

sealing, as in step 8. The plasterboard

sheets should be installed ull height

vertically.

8 Seal all joints at the perimeter o the

plasterboard using Knau Multi Purpose

Sealant to prevent air movement

behind the IWI System.

9 Mechanically fx the skirting boards

through the plasterboard to the

horizontal EcoStuds at the oot o

the wall, or fx them with a high

strength instant grab adhesive to the

plasterboard. Seal the skirting to the

oor with Knau Multi Purpose Sealantas a fnal precaution against air

leakage.

Figure 12

Figure 13

Figure 14

Figure 15

Footnote: The plasterboard selected should

be suitable or the activities to be undertakenwithin the space being upgraded. For

instance, where the walls may be subject

to mechanical damage, consider using an

impact-resistant plasterboard such as Knau

Denseshield (vapour check grade).

Pullout strengthPullout strength tests have confrmed that

EcoStud perorms equally to that o metal

or timber studs, 38mm drywall screws

or wood screws should be used when

securing plasterboard to EcoStuds.

Vapour check membraneEnsure all jonts, rips, tears and

penetrations through the vapour check

membrane are sealed prior to the

installation o the plasterboard.


17/2017

Wall openings

10 Around openings (windows, doors

etc), screw fx EcoStuds to the wall at

the edge o jambs, sills and heads as

determined by on site requirements

(Figure 16).

11 Line the openings with a thermal

laminate board, preerably, with

a minimum thermal resistance o

0.34m2K/W (e.g. 9.5/17.5mm

Polyoam Linerboard). I there are

thickness constraints due to the size othe window or door rame, install as

thick a thermal laminate board as is

practicable. The edge o the thermal

laminate board should fnish ush with

the ace o the EcoStuds (Figure 17).

12 The thermal laminate boards should be

fxed using adhesive or plaster dabs,

and additionally secured with localised

mechanical fxings. Complete continuity

o insulation should be achieved aroundthe opening at the junctions o heads,

jambs and sills by cutting back the

plasterboard at the edge o the laminate

board (Figure 18).

13 When setting out studs adjacent to

openings in relation to plasterboard

dimensions, make allowance or the act

that the plasterboard needs to extend

beyond the centre line o the jamb stud

to cover the thermal laminate board.For example, the dimension between

the centre lines o the jamb stud and the

next stud needs to be 600mm, less the

thermal laminate thickness (including

adhesive dabs), less 25mm (hal the

stud width) (Figure 19).

Figure 16

Figure 17

Figure 18

Figure 19

Installation at window and door openings


18/20

Installation at window and door openings

Figure 20

Figure 21

Stepped or check reveals

14 Install a new window rame towards

the outside o the wall and build out

head and jamb reveals with a suitably

sized timber infll piece to accommodate

the recommended thickness o thermal

laminate board, ensuring a strip o damp

proo membrane is fxed to the back

o the timber using galvanised nails or

stainless steel staples, i.e. between the

timber and the external wall (Figure 20).

15 Fix EcoStuds to the ace o the jambs

and ush with the timber infll piece

and orm a continuous insulated

lining around the opening with the

plasterboard cut back accordingly, as

step 12 (Figure 21).

Internal corner

Internal corners should be installed in

accordance with Figure 22 and the corner

void ully flled with Earthwool EcoBatt. Thecentre o the studs adjacent to the corner

studs should be adjusted to accommodate

the corner detail (Figure 22).

External corner

External corners should be installed in

accordance with fgure 23. In order to

provide additional rigidity at the junction

o the plasterboard linings a timber batten

(minimum 25mm x 25mm) should be

screwed fxed in position as indicated andthe corner void ully flled with Earthwool

EcoBatt. The centre o the studs adjacent

to the corner studs should be adjusted to

accommodate the corner detail (Figure 23).

Plasterboard nishing

techniquesTaping and jointing

In order to accommodate a taped and

jointed fnish, taper edged plasterboards

should be installed. Ater applying a primer

coat over the plasterboard and joints, a

reinorced tape and jointing compound

should be used to achieve a seamless

fnish. Knau Drywall provides a

comprehensive range o jointing

compounds and tapes.In all instances ollow the plasterboard

manuacturers instructions.

Skimming

A 2 to 5mm veneer coat o Knau

Multicover or Knau Universal Board

Finish can be applied to the ace o the

plasterboards. The board joints should be

reinorced with paper or fbre tape.

Decoration

Follow manuacturers instructions regarding

priming requirements prior to the installation

o wallpaper or specialist coverings.

Tiling

Face EcoStuds with Knau Moistureshield

or Aquapanel when installed in humid

or wet areas such as kitchens and

bathrooms. The weight o tiling (including

adhesive) fxed direct to plasterboard

(without plaster skim) should not

exceed 32kg/m2. Follow guidance

and recommendations rom tilingmanuacturers and BS5385 accordingly.

Figure 22

600mm

600mm

Figure 23

600mm

600mm

25x25mm (min)timber batten


19/2019

Electric cables

Electric cables give o heat when in use

and should be routed where they will not

be covered by thermal insulation, so the

heat can be dissipated. I cables need to

be located within insulation, they should

be run in conduit and possibly increased

in size. Advice on this should be sought

rom a suitably competent person, such as

a qualifed electrician.

PVC-insulated cables should be located

in suitable conduit to avoid being indirect contact with extruded polystyrene

insulation in order to prevent plasticiser

migration which can cause loss o

protection to the conductors.

Socket outlets

When socket outlets on the existing

external wall need to be repositioned on

the new EcoStud lining, it is likely that the

existing cables will need to be extended.

Extending cables in this manner is notclassifed as notifed work (according

to Approved Document P, 2006 Design

and installation o electrical installations)

and can be carried out by a suitably

competent person. All electrical work

should be carried out in accordance

with Approved Document P, the relevant

part o the current IEE Regulations and

associated Guidance.

Note: As with all electrical work, i at all in

doubt consult a suitably competent person such

as a qualifed electrician.

Socket and switch boxes

Socket and switch boxes should be fxed

into the plasterboard lining in accordance

with the manuacturers instructions.

Plasterboard and drywall socket and

switch boxes simply clip into place when

inserted into a pre-prepared opening.

When the ace plate is tightened onto

the socket box, the box grips against theplasterboard. Beore the ace plate is

fnally fxed, the boxes should be sealed

against the plasterboard using Knau Multi

Purpose Sealant to prevent air leakage(Figure 24).

Figure 24 A plasterboardsocket box

Heating radiators

Thermally upgrading the external wall in

a room may provide an opportunity to

have a smaller radiator and re-position

it on an internal wall. Alternatively, it

may be possible to replace wall hung

radiators with skirting radiators. Further

inormation should be obtained rom, or

instance, a heating engineer or radiator

manuacturer.

Fixing radiators

Do not fx radiators to plasterboard alone.

Sufcient support is provided only when

radiator brackets are fxed:

Through the plasterboard into the

EcoStuds

To horizontal timber battens, fxed

through the plasterboard to the

EcoStuds

To horizontal timber battens, fxed

between the EcoStuds and to the

masonry wall To Knau Drywall Fixing Channels,

screw fxed to the EcoStuds behind the

plasterboard

To the masonry wall using suitable

stand-o fxings.

Timber battens are suitable or loads up

to 75kg per metre run acting parallel to

the plasterboard and should be used or

heavier radiators.

Knau Drywall Fixing Channels aresuitable or loads up to 50kg per metre

run acting parallel to the plasterboard and

can be used or small radiators.

Picture rails and dado rails

Picture rails and dado rails should be

removed beore installing the IWI System

as they will prevent the EcoStuds being

fxed tightly against the wall. However,

picture rails and dado rails can be fxed

to the new plasterboard lining using an

instant grab adhesive ater installation o

the IWI System, or the rails can be fxed to

the EcoStuds using suitable screws.

Fixing to plasterboard

Light to medium weight items such as mirrors,

pictures, shelving and curtain poles can be

fxed in position using standard sel drilling,

winged or toggled plasterboard fxings and

fxings such as Knau Drywall anchors which

are suitable or loads up to 20kg acting

parallel to the plasterboard. For heavier

items, such as kitchen cupboards, specialist

heavy duty cavity anchor fxings should be

used. Universal wall plugs are also suitable

or use with shelving and cabinets. Heavier

items can also be secured by fxing back to

the masonry wall using proprietary stand-o

fxings or a suitably sized standard screw.

Alternatively, screw fxing a 10 - 18mm

plywood sheet to the ace o the EcoStuds

over the entire wall area (beore fxing the

vapour check plasterboard) provides a

solution to a wide range o fxing problems.

NB: I in any doubt as to the suitability o fxings,

consult the fxings manuacturer.

Accommodating xtures and ttings


20/20

RBB119909

Knau Insulation Ltd Customer Service (Sales) Technical Advisory Centre LiteraturePO Box 10 Tel: 0844 800 0135 Tel: 01744 766 666 Tel: 08700 668 660Staord Road Fax: 01744 612007 Fax: 01744 766 667 Fax: 0870 400 5797St Helens Email: [email protected] Email: [email protected] Email: [email protected] www.knaufnsulation.co.ukWA10 3NS

Knau Insulation LtdPO Box 10 Staord RoadSt HelensMerseysideWA10 3NS

www.knaufnsulation.co.uk

Email: [email protected]

Tel: 01744 766 600

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When you h ave finishe d withthis brochure please recycle it

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Brochure Internal Wall Insulation System Design Guide March 2010

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