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D39BR BUILDING REFURBISHMENT AND MAINTENANCE
Exam Preparation
This note is intended to help structure and provide a framework for your revision for
the exam. The undernoted topic labels can be used as core headline areas at the
centre of your reading, revision and preparation. There are of course many
surrounding and related issues that can be embraced in the preparation.
The better exam solutions tend to demonstrate a sound understanding of the
subject matter, generally through diversity and depth of related reading undertaken.
The core and supplementary reading indicated in the module provides guidance in
this. A greater grasp of the subject matter is usually apparent in discursive and
balanced solutions, which addresses the question well. Top quality students, will
show a deep theoretical understanding and practically apply the understanding in
writing with supporting sketches or diagrams where required.
Basic answers tend to be those that suggest a more limited range of reading has
been undertaken, with solutions which often appear superficial. You are required to
support or base your answers on reasoned argument.
Clearly annotated sketches, diagrams and graphs will be awarded with marks,
students should ensure that each component of their sketches are clearly labelled,
any specification details that can be provided as examples of the components will be
positively marked. Good answers should provide fully annotated sketches with a
clear description of the process that the sketch refers to.
Students will be expected to answer 3 questions. The first question from the
section A is compulsory. You will need to select two more questions out of the 4
remaining questions from the section B.
The exam aims to assess many aspects of the course and particularly
the following…
• Section A mandatory question requires students to present ideas regarding
the “change of use” options for a four storey old building in a report format.
o You should be able to provide recommendations for refurbishment of
flat roof and external walling.
o You should be able to link possible use changes with logistics,
location, economic and business factors.
o You should be able to identify challenges and limitations of the
recommended internal refurbishment operations for the given
scenario.
• There are water penetration and flooding problems in the basement.
o How did they emerge and the implications on the building fabric
o A proposal for resolving the issues
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• Warm pitched roof. Whole life costing implications of using warm pitched
roof.
• Access related issues during the maintenance and refurbishment of the
occupied buildings.
• BIM compliance of refurbishment activities.
Practical Tips for Exams Here is a list of practical tips for you to use, the list offers some guidance for you in
planning your exam strategy, it offers tips of things that you can do during the exam,
the list aims to offer practical ways to help you manage your exam experience and
improve your exam technique, the list is not exhaustive and is only mean to act as a
guidance note, you should read the list carefully and plan your exam strategy to suit
your individual.
Read the Questions and Choose you Exam Questions Carefully
• Always read all of the questions properly.
• Ensure that you are clear about the question posed and that you can answer
the specific requirements of the question.
• Students that attempt questions that they have not read and understood
properly or have a poor level of subject knowledge about can provide poor
quality responses as they responses are often not directed at the question
set.
Plan your exam time properly
• Every minute counts!
• Students often under perform in exams as they do not manage their time
well and can often run out of time. This may mean that whole exam
questions are not attempted or responses to exam questions are incomplete
and the opportunity to gain large numbers of marks can be missed.
• Ensure that you spend the appropriate amount of time answering the
required number of questions required for the exam.
• Research shows that the easiest exam marks to obtain are the marks
awarded initially, to gain more marks the quality of your answer must
increase; this is achieved through more detailed discussion of the key points
and /or a wider number of discussion points.
• In simple terms avoid spending your entire time answering one question
really well at the detriment to the other questions that you need to answer.
• Plan your time, a good example would be if the exam requires you to answer
three questions, allow yourself approximately the same amount of time for
each question.
• A good idea can be to complete in your opinion your best question first, i.e.
the one you have the most subject knowledge about. This will help you over
come any nervousness that you are feeling and help you to focus your mind
and increase your confidence levels. As opposed to attempting a question
that you may have less subject knowledge or understanding of and feeling
unsure or unclear about how to approach the question posed.
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Plan your written response
• Don’t waste time copying out the question posed, use you exam paper as a
reference point for the question, a good idea could be to write a very short
plan of your response, bullet point the key issues you are going to discuss and
then cross them off as you complete each one, this can act as an aid to
jogging your memory and ensure that you do not miss out any important
discussion points.
• Always leave space between each of your exam question responses, this
means that during the exam if you remember a new point you can go back
easily to your response and add in new points or ideas.
• More marks are awarded when the response to the exam question shows the
application of the subject knowledge to the questioned posed i.e. refer you
answer to the scenario provided in the question and make direct links to it.
• Exam answers that provide generic lists of information from the course notes
that do not apply directly to the questions posed will gain limited marks.
• At this stage in your studies you should be able to discuss the subject
material and apply it to the exact question set.
• Please avoid bullet point lists in your exam responses, at this level of study
more marks are awarded for discussion demonstrated through clear
comprehension and full sentences. Only resort to bullet points if you are
running out of time, as anything that you write will be positively marked if it
is applicable to the exam question posed.
Check your responses
• Use all the time allocated to you, if you have time, read through and review
your answers, at this point you may remember something that is relevant
that you want to add to your answer to enhance your over all response to the
question.
Finally
GOOD LUCK!
• Section A mandatory question requires students
to present ideas regarding the “change of use”
options for a four storey old building in a report
format.
o You should be able to provide
recommendations for refurbishment of flat
roof and external walling.
o You should be able to link possible use
changes with logistics, location, economic
and business factors.
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o You should be able to identify challenges and
limitations of the recommended internal
refurbishment operations for the given
scenario.
Recommendation for refurbishment of flat roof
OVER-ROOFING
(Tata catalogue) Trussed rafter system
This system is designed for use on existing roofs that do not have the
capability to support any further load. Instead, factory assembled clear
spanning trusses constructed using a series of purpose made sections are
supported by the existing load bearing walls or columns. Once in place, the
trusses are fixed into the connection plates, braced,and the roof purlins
secured. Depending on the size of roof the spanning trusses will be delivered
as a full unit or in two halves.
Indicative over-roofing design sketch:- a choice of 4 profile/ design
(Tata catalogue) Benefits: Roof upgrade – flat to pitch
• Provides a permanent solution to flat roof failure and moves water
drainage to the outside of the building.
• Framing systems are individually designed and tailored to suit
structural requirements
• There is minimum disruption to building occupants.
• Dramatically upgrades building aesthetics.
• Provides opportunity to easily upgrade thermal performance.
• Life of building considerably extended and future maintenance costs
reduced.
(Lesson 1 slides) Considerations:
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• Structure & condition of existing roof
• Extent & location of services
• Need for fire compartmentation
• Access around building (crane and storage)
• Disruption to tenants
• Programming of works where wall over cladding is also undertaken
Recommendation for refurbishment of external walling
OVER-CLADDING (for less disruption)
(BRM Notes pg 10:6)
Rain-screen systems:
Types: Drained and back-vented – typically metal or composite board
systems supported on a structural frame. The void behind the external
sheeting usually encloses thermal insulation and a ventilated cavity directly
behind the sheeting. This cavity is ventilated through gaps in this outer
sheeting. Condensation or penetrating rain water can drain down the back of
the sheeting where it is directed to the outside at regular flashings, see figure
below.
Requirements:
• Protection – to provide resistance to wind; wind driven rain/ snow;
impact damage and lightening. This protective aspect of the cladding
system probably provides the biggest challenges as the system must
resist a number of different forces, influences and effects.
• Appearance – the cladding finish must provide an acceptable
appearance in keeping with convention and the surrounding
environment. Typically constructed from panels and metal framing
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the completed structure needs to conform to conventional norms and
not resemble a caravan!
• Durability – the completed system must have a life span at least equal
to that of the overclad structure and where possible enhance this
service life. Over cladding is typically undertaken well into an existing
building’s ‘life’, i.e. 50-60 years, with the expectation that it will
extend this life by some considerable time.
• Insulation – most overcladding systems incorporate thermal
insulation to reduce heat loss and deadening to reduce sound
transmission from street noise or rain drumming.
Change of use and its justification – logistic, location, economic and
business factors
Change of use can be at the estate level whereby an entire precinct or area is
re-zoned for different use. For example Singapore’s new Marina Bay is a
reclaimed land and a lot of the conserved buildings which used to be sea
facing is now facing the bay and are no longer functioning based on its
original use as an colonial administrative office or as a pier. For example the
current The Fullerton hotel , Boat House, Clifford Pier etc.
Change of use could also be at the building level whereby the building is
converted to another use entirely. For example in Singapore with the opening
of two Integrated Resorts there is a tremendous increase of tourist arrival.
This resulted in some office buildings being converted to hotels. For example
– Innotel Hotel along Orchard Road.
Possible change of use
1) Hotel
2) Office
3) Service apartment
4) Hostel
5) Apartment for sale
Logistic factors
• Possible change of transportation nodes eg bus interchange , new
subway station
• Change of road network – implementation of expressway which
bypass the building
Location factors
• Possible change of the estate character – downgrading or upgrading
• Inclusion of major employment centre eg financial centres or shipping
companies or petrochemical plants
• New tourist attraction or varsity etc
Economic/ Business factors
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• Change in economic situation – change in purchasing power, income,
tourist arrivals, foreign investment , expatriate arrivals
• New retail innovation or products – competition from low cost carrier
or hotels
Some specific local examples of environmental impact which drives
refurbishment:-
Office
buildings :-
• Re-structuring of economy into more service oriented
industry – leading to an increase demand for high
specifications and technology office building for the
financial sector.
• Older office building without the necessary essential
specifications lose out in terms of competition
Shopping
malls:-
• Orchard Road – a regional catchment within and beyond
Singapore for mid to high end fashion and lifestyle
shopping. To cater to higher spending power several
building owners has recently built duplex store for luxury
brands flagship stores.
• The decline of certain trade or reduced demand for certain
products leading to the re-configuration of shopping malls.
Eg the expansion of Apple stores and decline of DVD, CD
shops.
• 2008 financial crisis – leading to the exit of Carrefour in
Singapore and aggressive regional expansion of other
retailer into Singapore and Asia eg Uniqolo , H&M
• Consolidate of large format department store – exit of
Sogo, Metro and expansion of Isetan, Robinson
• Proliferation of different store format – eg NTUC Finest,
Apple Store, food kiosk etc
Industrial
buildings :-
• Re-configuration to cater to changing industry output
requirement – addition of ramp , loading / unloading bay
Hotel:- • Upgrading of guestroom design to incorporate latest
entertainment and business technology eg wall mounted
Smart TV, wireless internet
• Upgrading of finishes and fittings to keep up with
competition arising from increase tourist arrivals and
higher expectations – eg Mariott Hotel 2012, Pan Pacific
Hotel 2012
Internal refurbishment operations – challenges and limitations
(BRM Notes Section 9.6)
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Challenges & Limitation
• Building structural grid may limit the desired layout of the new
buliding use
• May require additional structural strengthening or underpinning if the
new building use has higher structural loading
• Would disrupt existing user and tenants
• Existing building may be very old and information may not be
available or the existing structural integrity cannot be ascertained
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There are water penetration and flooding problems in
the basement.
o How did they emerge and the implications on
the building fabric
o A proposal for resolving the issues
How did they emerge and the implications on the building fabric
Water Penetration in basement
See documents
• “Luxfoundation Waterproofing”
• “waterbasement 2004”
• “FloodBrochure_v1”
• “BasementFloodingBrochureforweb”
A proposal for resolving the issues
(BRM Notes Section 11.12)
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Other measures
• Waterproofing basement walls – See document “Sika Basement
Waterproofing”
• Surface water drainage
• Sump pump
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• Warm pitched roof. Whole life costing
implications of using warm pitched roof.
See document “English Heritage – Insulating Roof At Rafter Level”
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Whole Life Costing
Definition: the systematic consideration of all relevant costs and revenues
associated with the acquisition and ownership of an asset. In construction,
this is expected to take into account capital or procurement costs such as
• purchase or leasing,
• interest
• fees, and
• initial construction or major refurbishment,
plus the recurring or occupancy costs such as:
• rent
• rates
• cleaning
• maintenance, repair, replacement / renewal
Warm pitched roof whole life costing
Initial cost
Refurbishment cost is higher than cold roof but possibly cheaper than over-
roofing.
Recurring cost
Rent – may attract higher rental as warm roof is preferred as compared to
cold roof
Cleaning – cleaning cost is no different from that of cold roof. Usually only
the roof covering and rain water pipes needs to be cleaned
Maintenance – as warm roof helps to reduce condensation there will be less
issue of water penetration or dampness issues. Hence long term
maintenance and repair cost is reduced.
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• Access related issues during the maintenance and
refurbishment of the occupied buildings.
Access related issues during refurbishment of an occupied building
(BRM Notes Section 5.4)
(BRM Notes Section 5.12)
(BRM Notes Section 6.5.1,6.5.2)
(BRM Notes Section 7.2)
(BRM Notes Section 8.3)
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(BRM Notes Section 9.14)
(BRM Notes Section 10.5) – over-roofing
(BRM Notes Section 12.6) – constructional factors
Access related issues during maintenance of an occupied building
(BRM Notes Section 6.4.1)
(BRM Notes Section 7.5)
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(BRM Notes Section 8.6.1)
(BRM Notes Section 8.8.1)
Especially BRM Notes Section 12.14!!!
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• BIM compliance of refurbishment activities.
What is BIM
(Autodesk) BIM is a process that involves creating and using an intelligent 3D model
to inform and communicate project decisions. Design, visualization, simulation, and
collaboration enabled by Autodesk BIM solutions provide greater clarity for all
stakeholders across the project lifecycle. BIM makes it easier to achieve project and
business goals
Building Information Modeling (BIM) is a process involving the generation and
management of digital representations of physical and functional characteristics of
places. Building Information Models (BIMs) are files (often but not always in
proprietary formats and containing proprietary data) which can be exchanged or
networked to support decision-making about a place. Current BIM software is used
by individuals, businesses and government agencies who plan, design, construct,
operate and maintain diverse physical infrastructures, from water, wastewater,
electricity, gas, refuse and communication utilities to roads, bridges and ports, from
houses, apartments, schools and shops to offices, factories, warehouses and prisons,
etc.
(BCA)
Building Information Modeling
• Is a process from silo-based environment to collaborative and coordinated practice
It is
• a data rich digital model
• Object based relational database
• a model with Intelligent objects
What can BIM do / Benefits of BIM
(BCA)
• Collaboration
• Review clashes
• More efficient process – faster decision making, tighter check on compliance
with code, seamless flow for the entire building life cycle etc
• Integrate information / database
• Improved collective understanding of design intent
• Improved overall project quality
• Reduced conflicts during construction
Singapore BIM development
• July 2013 – mandatory architecture BIM e-submissions for all new building
projects >20,000sqm
• July 2014 – mandatory engineering BIM e-submissions for all new building
projects > 20,000sqm
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• July 2015 – mandatory architecture & engineering BIM e-submissions for all new
building projects > 5,000sqm
BIM compliance and refurbishment
• BIM compliance is usually not required for refurbishment project as the scope
tends to be smaller as compared to new construction. Government roll out of
BIM compliance tends to focus on large scale building projects as they would
have the financial resources to do so.
• BIM compliance requires the investment of financial resources on BIM compliant
software and systems. It also requires the training of human resources as well as
the regulatory regime to mandate the use of BIM.
• Increasingly refurbishment needs to be “green” and value for money. Hence BIM
is very suitable in capturing geometric and non-geometric information which
could assist decision making using whole life cycle calculation. BIM is also
collaborative and serves as a good platform for integrated design approach.
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Term Definition
Compare Look for similarities and differences between; perhaps reach
a conclusion about which is preferable
Contrast
Set in opposition in order to bring out differences Criticise
Give your judgement about the merit of theories of opinions
or about the truth of facts; back your judgement by a
discussion of evidence or reasoning involved
Define
Set down the precise meaning of a word or phrase. In some
cases it may be necessary or desirable to examine different
possible or often used definitions
Describe Give a detailed or graphic account of
Discuss Investigate or examine by argument; sift and debate; give
reasons for and against. Also examine the implications
Evaluate
Make an appraisal of the worth of something, in the light of
its truth or usefulness. Include, to a lesser degree, your
personal opinion
Explain Make plain; interpret and account for; give reasons for
llustrate Use a figure or diagram to explain or clarify, or make clear by
the use of concrete examples
Interpret Expound the meaning of; make clear and explicit, usually
giving your own judgement also
Justify Show adequate grounds for decision or conclusions; answer
the main objections likely to be made to them
Outline
Give the main features, or general principles, of a subject,
omitting minor details and emphasising structure and
arrangement
Relate a) Narrate - more usual in examinations
b) Show how things are connected to each other, and to what
extent they are alike, or affect each other
Review Make a survey of, examining the subject carefully
State Present in a brief, clear form
Summarise Give a concise account of the chief points of a matter,
omitting details and examples
Trace Follow the development or history of a topic from some point
of origin
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Sample Answers
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DEFECTS LIKELY CAUSES REPAIR AND MAINTENANCE TIPS
Mechanical damage due to
objects dropped on tile surfaceConduct regular inspection
Improper installation of tiles
onto roofReplace damaged or loose tiles
Tiles dislodged by strong winds
Corroded wire used to tie tiles
to battens
Engage specialist to jet wash the
roof surface
Spray anti-fungal solution on
roof surface
Termite-infestationRemove and replace all affected
timber units
Decay of timber in contact with
damp brickwork
Apply anti-termite treatment
under base slab
Apply anti-termite treatment to
wood
Use properly seasoned wood
Apply remedial treatment to
wood, eg. drying out,
application of wood
preservatives
Choked roof gutter due to fallen
leaves and branches
Cover gutter with appropriately
sized wire mesh
Undersized or blocked rainwater
outlet
Regular inspection of gutters
and gutter supports, once a
week, especially if there are
trees in the vicinity, to clear
away leaves which prevent
water from draining away
Cracked gutter due to wear and
tearRemove debris from all gutters
Insufficient fall in gutter
Check that drainpipes are
draining properly by water
testing them
Paint roof gutters with
insecticide paint to prevent
mosquito breeding
Local tropical conditions of
constant high humidity and
heavy rainfall
Apply protective metallic
coatings or paints to steel
sheeting
Deposits of wind-borne salts
and atmospheric sulphur
particles and other pollutants
Consult specialist for repairs
Ponding in sheet metal roofing
Inappropriate gradient (fall) of
roofing profile, preventing
speedy drainage of rainwater to
gutter and rainwater drainpipes
Ensure appropriate gradient in
metal roofing, according to
system selected
Leaks due to cracked, loose clay
tiles on pitch roof
Stained clay tiles on pitch roof Growth of algae
Rotting supporting timber rafters,
purlins or battens
Leaks at roof gutter
Rusting and corrosion in ferrous
metal roofing (especially in
profiled steel sheeting used to
line soffit of projecting eaves and
underside of projecting canopies)
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Question 2
The findings from a detailed condition survey of your client’s building have identified a serious issue
with condensation and water penetration related to the pitched roof. Provide your guidance and
recommendations to your client on the following:
a) The significance of the defects, i.e. explaining how these defects came about and how you
would determine their priority when considering remediation.
b) A long term maintenance plan to reduce the risk of recurrence.
Answer
Condensation is the process by which water vapor in the air is changed into liquid water. In other
words, the water in the air, a gas known as water vapor, from your “hot” atmosphere gets in contact
with a “cold” surface. This caused the water vapor to condense, or turn into its liquid form i.e. water
vapor, from your hot shower cooled when it met the surface of the cold mirror and would noticed it as
moisture or beads of water and fog that has formed on the mirror.
Examples of physical breakdown
The possible cause of condensation and water penetration could be due to a physical breakdown,
specific failure or impaired performance of material, component or element such as waterproof or
weatherproofing elements, skins or coverings, e.g. bituminous felt roofing; slate tiling; external
rendering; paint finishes from the closures at openings, e.g. water bars; sealants; drips of the installed
dormer(s), windows and doors at the pitched roof.
Failure of the M&E services to and from the building, e.g. hot and cold water; gas, electric, foul
drainage might also resulted in the variance of inner building temperatures that would alter the
percentage of moisture, where the relative humidity (RH) will be affected.
Consequences of failure
Depending on the scale and magnitude of the issue(s), it can be an economic disaster, either direct or
indirect as it would involves financial costing, depending whether it is short or long term, i.e. a water
leak at roof level may take many years to cause (costly to repair or replace) timber decay in roofing
timbers.
From technical aspect, consequent failure of components, elements or building services due to an
isolated building failure, e.g. water ingress can seriously impair or damage electrical services and we
may need to re-run the electrical services.
We might expect legal claims or action initiate by members of public, staffs, users, Tenant(s), etc.
arising from any injury and/or impairment sustain due to the noncompliance. Where the breach or
injury is serious, these costs may outweigh the maintenance bill many folds.
Lastly, the Tenant(s), staff(s), etc. would suffer loss of use or enjoyment of the building as result of
failure.
Disturbance & interruptions to building in use:
- Decanting – the removal (partial, full or phased) pf any occupants within the building.
Decanting arrangements can be highly disruptive to normal site work patterns as noise, dust,
material and labour movements have to be coordinated with these third parties.
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- Partial closure – similar to decanting, where part of the building is cleared of tenants during
phased works.
- Restricted working hours – in some highly sensitive environments, e.g.
hospitals, MINDEF establishments, banks, etc. working hours may require to be limited.
Typically working after normal working hours; weekends; nights; public holidays, etc. is
expensive and can be unpopular with contractors.
Noise and dust control: where the rectification works is being undertaken within or close to an
occupied building; or where sensitive equipment or finishes are being preserved; or where there are
local environmental restrictions (statutory) there may be a need to strictly control noise and dust
emission from the site. These additional controls add cost in term of equipment, management and
(indoor) air quality monitoring.
Problems Areas
Leaks: roof lights have to be effective sealed around their perimeter to prevent moisture penetrating.
In addition to an effective perimeter water seal, overlying roofing membranes require to be properly
lapped to prevent water being directed into the roof.
Condensation: glazed (even double and triple glazed) roof lights represent a considerable thermal
bridge, resulting in colder internal surfaces and the formation of condensation. This is a particular
issue, where the glazing emits to a cold night sky.
Heat gain: increased internal temperature can arise during sunny periods
Ventilation: in order to reduce the risk of condensation within these thermally upgrading roofing
elements it may be necessary to introduce ventilation to the underside of external membrane,
sheathing or cladding. In order to accommodate this additional insulation and ventilation, it may be
necessary to increase the thickness of these elements.
Structural alternations
Repairing defective structural members:
- Decaying joist ends or rafter feet – timber decay as a result of long term wetting can result in
a need for joist ends to be replaced. Replacement requires that the existing roof loadings be
transferred from sound timbers to the wall or vertical columns until timber is reinstated.
- Sagging floor joists ties/purlins – over time, overloaded or wide spanning floor or roof
timbers can sag. Remedial works to these timbers may require that the applied loads be
temporarily diverted.
Structural requirements (Structure) Condition:
- Deteriorated – materials can deteriorate for a number of reasons, e.g. exposure to weather/
water; excessive loading or extremes of temperature, and careful assessment needs to be
undertaken to ensure that affected structural components will effectively support the existing
or/and any new loading.
- Minimal repairs required – some damage may appear worse than it is. By way of example:
joist ends damaged by water ingress may cause the whole floor to sag or move. However,
limited replacement of the joist ends may resolve the problem rather than complete removal
and replacement.
Thermal Insulation (Energy) Key
elements:
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- Main walls – insulation can be applied to the internal or external faces of outer walls or
introduced as cavity fill.
- Roof – Insulation (typically mineral or rock wool quilt) is laid between and over ceiling
joists. In major roof refurbishment works, where slating/tiling and roofing battens are
replaced, consideration could be given to introducing sarking insulation, laid over existing
rafters.
Typical external refurbishment
Re-roofing - Recycled/ artificial slates – on the pitched roofs, it is common to strip off existing (aged)
waterproof covering (slates and tiles) and replace with lightweight, recycled or reconstituted
slate systems.
Window replacement: typically undertaken as part of an overall thermal upgrade of the building.
However, PVC-U windows are also routinely introduced when older timber or metal windows are
approaching the end of their service life.
Typical internal refurbishment
- Improved ventilation – to reduce the risk of condensation from moisture laden air
transferring throughout the building
Dampness and structural repairs:
- Timber decay eradication – decayed timber is structurally unsound and potential unsafe.
Eradication can range from the removal and replacement of a few floor boards to the
complete removal and replacement of joists, wall plates and floor boards.
- Condensation and other dampness control – this is an extensive area. Typically the remedial
measures must include eradication or reduction of the moisture source and replacement or
repair of any affected materials and components. Refurbishment measures include:
introduction of mechanical/passive ventilation; improved drainage; timber decay eradication
Upgrading pitched roofs Coating existing covering: application, typically involves careful cleaning of the existing substrate
followed by a two coat application incorporation a reinforcing fabric. The correct installation of this
reinforcement is vital to prevent excessive movement and cracking of the completed membrane due to
the high variations in temperatures experienced by roof surfaces.
Replacing roof coverings:
- With same – complete removal of the existing tiling/ slating system will be required. Battens
will only need replacing where these have deteriorated.
- With different – the existing roof coverings and secondary supports (battens, framing, cleats
etc.) will need to be removed to expose primary structural support. Where a heavier water
proofing system is to be applied, this primary structure (rafters, trusses) may need to be
stiffened, braced or upgraded to accommodate this increased load.
Thermal upgrading:
- At ceiling level – mineral wool quilted rolled over and between ceiling joist. Care needs to
be taken to ensure that effective eaves and ridge ventilation is installed and is clear of
blockages.
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- Sprayed-on insulation to underside of pitched roof deck – typically a foamed plastic
(polyurethane) spray applied to the underside of sarking boarding to form an insulating layer.
Ventilation v “sealed” roof: with the introduction of vapour permeable membranes, roof can now be
constructed without ventilation at eaves and ridge, i.e. relying on the natural vapour diffusion through
the membrane to dissipate any moisture in the roof space. Although most systems have Agreement
certification care needs to be taken when specifying, particularly where the roof encloses kitchens or
bathroom.