Case Study Flashcards
What was included in a Listed Building Consent application?
- A completed application form.
- Site & Location plan
- Floor Plans and Elevations
- A certificate of ownership.
- Design and Access Statement /Heritage impact assessment
What is a Design and Access Statement /Heritage impact assessment
Brief description of the building’s history and background to the proposals which form the basis of the application.
With justification on how the proposal helps to preserve the character of the building and historic fabric. (include photographs).
What is a certificate of ownership
Certificate confirming the applicant is either the sole owner of the land or that notice has been served on all owners /tenants.
This is required in accordance with Section 11 of the Planning Listed Buildings and Conservation Areas Act 1990.
There are four certificates A-D, covering a range of circumstances.
Where the applicant is not the building owner, notices must also be served.
What was the non-material amendment for?
The design approved by the LA was for side hung windows.
The owner of the apartment requested for the windows to be top-hung and therefore this change did not materially alter the proposal, but consent was required for the change.
How were the existing casements hung? Why was this not considered?
The existing casements were top hung, I considered this to be due to the angled design.
The design was ultimately approved by the directors who were happy with the side hung style.
The issue was that it wasn’t their apartment and ultimately shouldn’t have been their decision.
Did the non-material amendment affect the LBC?
There were no requirements set for which way the casements were to be hung in the LBC.
This was due to the dormers being located on a modern extension that was out of view of the wider conservation area and therefore having no impact no impact on the appearance of the building or the wider conservation area.
When I lodged the non-material amendment, I was informed that an amendment to the LBC would not be required and the change in the casement still discharged all of the conditions set in the listed building consent.
I am aware that you can not alter any conditions set by LBC and that a new application would be required.
What was the time frame for the non-material amendment?
28 days
What was included within your fee /service proposal?
- Scope of services /limitations.
- Proposed Fee /Payment terms.
- Complaints handling procedure.
- T&C’s of business and specific services.
What are the implications if T&C’s are not provided?
- Nothings in writing for what has been agreed.
- It wouldn’t be considered professional /reputational damage.
- Lack of transparency
- A complaint handling procedure may therefore not have been issued which is a breach of the RICS code of conduct.
Who was responsible for paying your fees and who was the fee proposal sent to?
The client ‘Homestead’ was responsible for paying the fees who had been appointed by the building owners to manage the property (externally and communal area).
What if homestead didn’t pay your fees – would you then go to the owners?
No, the agreement was between AG and Homestead who were responsible for paying our fees.
The fee would have been discussed directly between homestead and the board of directors in a separate meeting who confirmed their willingness to pay.
AG were then appointed for the instruction.
What contract did you use for the works?
JCT Intermediate Building Contract with contractors design
- Tradition procurement
- Allowed appointment of sub-contractor who was liable for a specific section of design (waterproofing system).
Did the sub-contractor enter into the contract?
The Contractor entered into a sub-contract agreement with the named person. ‘Intermediate Named Sub-Contract Agreement.
Within 14 days of the date of issue of the instruction.
In terms of the named sub-contractor, what would happen if the principal contractor went bust?
The named-sub contract agreement would then be terminated between the contractor and named sub-contractor.
In this instance, I would look at Novation of the contract (transferring the benefits and burdens of a contract to a third party) to continue the works.
Who was the contract between?
The contract was between the principal contractor and the director’s private limited company.
The owners had a share of freehold which formed a private limited company.
What is a share of free hold?
Share of Freehold is where the individual flat owners own the leasehold for their flat and hold a share of the freehold for the entire building and the land it is built on collectively owning the whole freehold.
One method of managing a share of freehold for a property with more than four freeholders is to create a private limited company.
The company would be registered as the building’s freehold owner and the other co-owners registered as shareholders and directors of the company.
The board were nominated directors of the company with the rest remaining as shareholders.
What was the restricted access in terms of height to the rear?
Fixed restriction of 2.5m height.
Was there any other type of lift possible other than a MEWP for maintenance /undertaking the works?
I considered a scissor lift but the rear access was for pedestrian use only.
The adjacent church building had a wrap around extension for the church hall.
If a MEWP was used to the front elevation, what would you consider?
If any road closure were required
Checks with the local authority for permits.
Operators had IPAF licences.
What were the limitations of not using a MEWP and a pole camera instead?
Preventing close inspection without being able to physically check the timber for moisture reading and durability.
How were the high-level repairs undertaken?
Scaffolding – a low loader was parked up in the rear car park and scaffolding walked through the pedestrian entrance and erected.
How was the scaffolding fixed to the building?
The scaffolding was buttressed up to the building without the need for mechanical fixings.
What H&S risks are you aware of in terms of scaffolding?
- Fall from height /edge protection.
- Adjacent overhead power lines
- Poor ground conditions
- Vulnerability to vehicle impact.
- Preventing unauthorised access on to the scaffold.
What did your Design risk assessment include?
- Falls from height.
- Asbestos (particularly the basement used for thermal insulation).
- Movement of vehicles from the rear car park.
- Preventing unauthorised access on to the scaffold.
- Potential for lead based paint (banned in 1992).
Option for splice repairs to window frames, would there be any health risk to sanding down and splice repair of the existing frames?
The potential of lead paint; however, the windows were installed in 2002 – I am aware that lead based paint was banned in 1992 and therefore extremely low risk.
Was there any Planning condition to the approval?
Construction must be in accordance with the specified materials.
Works must have started no later than 3 years from the date of consent.
No samples were required for discharge of conditions; however, I am aware that this may be the case under section 106 of the Town and Country Planning Act 1990.
What is your understanding on conditions attached to a planning approval and how can these impact the works?
Planning obligations are legal obligations entered into to mitigate the impacts of a development proposal.
This can be via a planning agreement entered into under section 106 of the Town and Country Planning Act 1990.
Note: Decision can take up to 8 weeks.
You identified wet rot; what are the other types of rot?
- Wet Rot
- Dry Rot (internally)
What are the causes of wet rot?
- Excessive moisture present over a long period of time.
- High moisture content 50-60%
- Leaking services
- Building material failure
Wet rot is a type of fungus which affects wood that is wet.
Wet rot is commonly found in timbers that have become damp due to excess moisture.
What are the causes of dry rot?
- Leaking plumbing
- Poor ventilation
- Moisture content up to 30% considered damp not wet.
How would you identify wet rot?
- Found internally and externally.
- Infected timber turns dark brown in colour.
- Surface cracking where cracks follow the timber grain.
- Hyphae strands which are light brown & yellow (a key difference from dry rot).
How would you identify dry rot?
- Found internally usually in poor ventilated areas.
- Cuboidal cracking caused by shrinkage
- Lightweight and crumbles.
- Mycelium (Grey when wet and yellow when dry)
What remedial works can you undertake for wet rot?
- Remove the source of moisture.
- Wet rot is limited to areas in which wood has become wet: therefore, size of outbreak is closely linked to extent of wetting.
- Remove all rotted timber and replace – the wood that remains structurally intact and in a safe condition should be treated with a fungicidal spray to protect them whilst they dry.
What remedial works are available for dry rot?
- Removing the source of moisture.
- Dry rot can spread.
- Remove all rotted wood by cutting away timber 300–450 mm beyond the last evidence of fungus or rot.
- Applying a fungicide treatment to the remaining nearby timbers.
- Ventilation must also be ensured to prevent further occurrences.
What other timber defects you are aware of? (excluding rot)
- Structural damage.
- Infestation (woodworm, furniture beetle, deathwatch beetle).
Why was building paper used beneath the lead?
Allow for free movement of the lead during temperature changes.
Reduces corrosive attack when laying lead onto the timber deck.
BS 1521:1972 Specification for waterproof building papers
Was the root cause of the moisture ingress to the basement? Could it have been a building defect?
The cause of the ingress was through the natural rise of the water table allowing water to enter the structure through the defective waterproof system.
The drainage was also checked via a CCTV survey to rule out the potential of defective drainage.
You mentioned the issue with the cementitious tanking was maintainability, how would you prevent this from being punctured?
The system would have been recorded in the O&M (Operations and Maintenance) manual to prevent this.
However, cavity drained systems are not designed to keep ground water pressed behind once entered the structure – lower risk.
Cavity drained systems also have a series of inspection points for maintenance whereas tanking systems don’t and therefore leaks can often be difficult to trace.
What was the timeline for the window and basement repairs?
The works were undertaken concurrently.
How was CDM managed if the works were undertaken concurrently - who was principal contractor?
- The works were generally short in duration 6-8 weeks in total.
- The waterproofing works were concurrently alongside the window works.
- The principal contractor was the contractor who installed the dormers who also undertook minor repairs elsewhere (decoration).
Who accepted design responsibility for the basement solution, you or contractor, or consultant? How was this documented?
The design portion of the basement was covered by the consultant within the design portion of the contract.
This was satisfy their warranties.
What diligence did you undertake when selecting the consultant and the contractor?
Contractor
- The contractors were selected from my firms list of approved contractors.
- The contractors are required to submit a pre-qualification questionnaire.
Specialist
- The specialist waterproof consultant was selected from an approved list of installers found on the British Structural Waterproofing Association website.
What’s included within a Pre-Qualification Questionnaire?
- Company Name /contact details
- Type of organisation (sole trader /limited company)
- Number of employees
- Sub contractor arrangements
- Insurance details
- Accreditations (CHAS) /Membership of trade bodies (GAS Safe)
- Training records (Asbestos awareness)
- Experience
- H&S policies
- Convictions (fraud /bribery /money laundering etc.)
What was the level of PI insurance the contractor and specialist contractor had and how did you asses this was reasonable?
£2million
Excluding the first £2500 each and every claim.
I considered this to be reasonable given the value of the works (circa £30k) and design liability.
How did you check the PI cover?
I checked the insurance documentation at high level ensuring that:
- Contractors name on the policy
- Date of commencement /expiry
- The amount of cover was deemed appropriate.
I sent the insurance details on to the client for their legal team to assess in more detail.
Whats the difference between Public Liability Insurance and Professional Indemnity Insurance?
- Professional indemnity insurance cover claims made by clients for professional negligence.
- Public Liability Insurance covers claims made by members of the public for injury or damage. (usually £5mil)
How was the studwork fixed over the drainage channel?
The lower sole plate was be glued to the floor.
A noggin was placed slightly higher and secured into a plug to provide bracing.
How is the studwork fixed to the cavity drained membrane?
The stud is fixed via a plug and screw which is designed to form a watertight seal.
What is a listed building?
- A designated building of Special Architectural or Historic Interest
- Assessed by English Heritage and placed on the Statutory List of Buildings.
- The authority for listing is granted to the Secretary of State by the Planning (Listed Buildings and Conservation Areas) Act 1990.
What Grades of Listing are there?
Grade 1: Exceptional interest.
Grade II*: Particularly important of more than special interest.
Grade II: Special interest
What protection does listing give a building?
Buildings are listed to protect them from demolition or insensitive alterations.
This includes altering either outside or inside in any way which would change its character without written consent in the form of a Listed Building Consent.
What is the listed building or conservation area protected under?
Planning (Listed Buildings and Conservation Areas) Act 1990
How did you know the building was listed?
Through knowledge of the area.
I checked the Local Authorities website and used their planning map search.
For further information I visited Historic England’s website to review the National Heritage List for England (official listing).
Which part of the building was listed?
- The listing protection applies to the whole building.
- Including structures that are fixed or within the curtilage of the listed building.
Why was the property Listed?
Due to the special architectural and historical significance.
In 2005, ‘Reasons for Designation’ was added to the listing – as this property was listed prior to this date there was no indication as to why it was listed.
How did you identify the age of the building?
I identified the property was constructed circa 1850 through reviewing National Heritage List for England. (property listing)
I further researched local archives and the history of Winkley Square which was part of Preston’s residential expansion at the beginning of the 19th century.
I confirmed this during my site inspection by identifying typical construction detail:
- Solid wall construction
- Sliding timber sash windows (symmetrical – suggesting Georgian mid 18th Century)
- Slate roof covering
What is a town house?
A tall, narrow traditional terraced house, generally having three or more floors.
What are the common defects you would find on an 1850s building?
- Failure of slate roof covering through nail fatigue.
- Damp issues due to the solid wall construction /insensitive repairs such as cementitious pointing.
- Poor thermal performance of building materials.
- Rotten timber windows and failed sash mechanisms.
How do solid walls work and why is cementitious pointing bad?
- Lime mortar is applied to solid wall construction to allow the moisture to evaporate and move out freely.
- When moisture levels are high the lime mortar can absorb water vapour preventing potential damage from moisture penetration.
- When conditions are dryer, lime mortar releases the trapped moisture back to the environment.
With other types of mortar such as cementitious – moisture gets trapped within them which can lead to dampness and structural issues (freeze-thaw action)
Cementitious mortar is much harder than lime and less flexible. This may be incompatible with older bricks leading to spalling where the surface layer of the brick flakes off.
What is a mansard roof?
A mansard roof is a multi-sided hip roof with the lower slope at a steeper angle than the upper.
How did you obtain the client brief?
- Upon taking the initial instruction from the management agent who had received various complaints of defects by the board of directors.
- I arranged a MS teams call with the board and client prior to my site visit to ensure all issues raised were covered.
- This also painted a clear picture of the scope of works and time spent to inspect to develop a fee proposal.
What were the client’s objectives?
- To identify the cause of decayed timber windows and a feasible solution to remedy.
- To identify the cause of damp staining to the basement.
What formed part of your desktop study?
- I initially reviewed the site via google maps.
- Reviewed the planning portal for details on the conversion works.
- Reviewed National Heritage List.
What did you consider when preparing the fee quotation?
- I considered the size of the building the complexity of the appointment taking into consideration the Listed Status.
- I then considered the time required to complete the inspection.
- Followed by correspondence with the local authority and specialist consultants.
Were there any limitations other than access to the rear?
- windows viewed via a pole mounted camera
- One of the limitations were that I could not confirm the freedom of defects within the apartments I was unable to gain access to.
- Limitations were set out in terms of the legal effect of the lease in relation to the service charge obligations.
- I did not provide any advice weather or not it was the client’s responsibility for carrying out the repairs /liability to pay towards the costs.
- It was apparent that costs were split between each apartment owner a sum of which had already been accounted for within the service charge.
- However, to determine the fact on the service charge obligations was the responsibility of the client’s legal advisor.
What historical data did you use in your desktop study?
- Local history archives
- Historical maps
- National Heritage List for England.
How did the historical data influence your approach to inspecting the building?
To determine which areas of the building was of potential historic significance and the original fabric of the building.
What was the specific methodology did you use for inspecting the building?
I adopted a top-down approach for the inspection, carefully examining the external areas beginning with the roof and working downwards followed by internal elements of the building.
What were the key elements you considered when managing the conservation and restoration of the property?
Key elements considered included:
- Minimising impact on the original fabric.
- Maintaining the architectural style,
- Compliance with heritage regulations
- Ensuring cost-effectiveness and sustainability.
Can you discuss the challenges presented by the fact that the building was located within a Conservation Area?
- Adherence to regulations
- Obtaining permissions
- Ensuring that the works did not affect the overall character of the area.
How did you locate the windows to the rear mansard roof on your desktop study?
The client brief explained the location of the windows to be on the top floor of the rear out rigger.
I viewed the site with an aerial view from google maps and noted the windows to be part of what looked like a modern extension.
I then visited the local authority’s website and identified the extension formed part of the conversion works in 2002.
In terms of access, why was the vehicle height restrictors an issue?
To the rear of the building was a church hall with a pedestrian gate accessing the courtyard area to the subject property.
Therefore, the MEWP would have had to extend over the church hall and extend outwards towards the windows – given the size of machinery required to do this the vehicle height restriction of 2.5m was questionable.
This also prevented the risk of damaging the church building which had ornate features such as a cross on the roof top which would also have to be worked around.
What things would you consider when using a MEWP?
- Ensure the ground is suitable for MEWP operation. It should be in good condition, flat and able to withstand the applied pressure of the platform.
- Any outriggers being used must be extended and grounded before work commences.
- Effective guardrails must be fitted to the platform.
- A harness must be worn; this should be attached to a suitable anchor point within the basket so that the wearer cannot fall from the platform.
- Avoid working in high winds as these can tilt platforms and make them unstable.
- Nearby potential hazards must be assessed such as nearby overhead cables.
- Ensure that the platform does not protrude over any traffic routes.
- Permits are sometimes required for example for use on a high street.
Was the fee proposal altered when taking the decision to not use the MEWP?
The access limitations were identified during my desktop study which was undertaken prior to the fee proposal.
I therefore did not include the hire of a MEWP in the fee proposal.
Why did you undertake a desktop study prior to the fee proposal?
To review the site and gain a clear picture of the work involved to accurately quote for the instruction.
This included identification of the listing, conservation area, planning portal and access to the site.
You carried out a measured survey of the site – can you explain what processes you followed any why?
I followed the RICS Property Measurement guidance and measured the building in accordance with IPMS 1.
Why did you use IPMS 1 when measuring the building?
IPMS 1 is used to measure the Gross External Area which is required for planning permission.
How did you procure the works?
The works were procured via a traditional procurement method using a JCT Intermediate Building Contract with contractors design.
Why was a traditional procurement method used?
- The client had greater control over the design.
- Ensuring the design and scope of works were agreed in full prior to the works commencement.
Why was a JCT Intermediate Building Contract (with contractors design) used?
I reviewed the JCT decision tree and found this contract was the most appropriate to allow for a specialist contractor to be named to undertake and design the waterproofing works.
- The Employer had the freedom to choose the sub-contractor for the specialist work.
- The Contractor carries all the risk for the Named Specialist (except when the named specialist becomes insolvent).
How did you manage the communication between the stakeholders?
- I hosted an initial briefing meeting with both the client and board of directors. This enabled introductions and clear lines of reporting.
- Although my client was Homestead it was a crucial part of the project to keep all directors informed.
- I did this by hosting design meetings via Microsoft Team’s.
- During the works, I sent out regular updates via email with all directors and the client in the email chain.
How did you monitor works progress and quality?
I monitored the works every 2 weeks and at key intervals such as:
- Windows removed.
- Before dressed with lead to ensure the timbers were as per the SE design and building control compliant.
- I took photographs of the works at each stage which were used as evidence to support Building Control sign off.
Can you talk to me about the construction phase were there any issues?
The works were well planned and managed from the outset with defects identified.
This ensured a smooth running of the project with minimal issues.
The main issue I encountered was that the Local Authority no longer had a conservation officer employed.
This made communications difficult in relation to the heritage aspect from the outset.
Did the 5-week delay entitle the contractor to an extension of time?
No, the delay came to light prior to the works commencement date and therefore this was postponed.
The contractor was happy to delay the commencement date due to other workload.
Would the contractor been entitled to an extension of time due to the delay?
No, there was no contract in place at the time.
If there was a contract in place this would have been acceptable due to delays caused that were outside the contractors control.
What was the period of validity of the tender?
- The period of validity was for 3 months.
- This enabled the contractor to re-submit their tender on this basis, but they chose not to.
How did you manage the named sub-contractor?
- The sub-contractor was managed under the principal contractor in which they included for management costs within their tender.
- I regularly monitored all works on site.
How did you know it was wet rot to the window frames?
The exposed position of the windows and poor design of the angled casement allowed the windows to be consistently exposed to moisture.
The dark staining of the timber and evidence of warping to the glazing bars signified the high moisture content of the timber.
What are the conditions for wet rot to develop?
Wet rot fungus thrives within timber that is exposed to excess moisture.
High levels of moisture provides an ideal breeding ground for the spores that the wet rot fungi releases.
- Excess moisture is present in timber over long periods of time.
- Wet rot will begin to grow when the moisture content of the timber reaches around 50%.
How did you identify the cills were angled back?
- There was rainfall in the early hours of the morning; I inspected mid-afternoon and there was evidence of ponding to the cills between the cill and the window bottom.
- It was clear the cills were slightly angled back inline with the window position.
- The rot to the frame was localised to the lower portion suggesting this was where water was holding /not discharging.
How did you identify a lack of maintenance to the timber windows?
The upper floor windows had clearly not been maintained in comparison to the decorative and overall condition of the lower floors.
I considered this to be due to the restricted access of the windows.
Were the current condition of the windows deemed to be an H&S issue and was this reported?
I raised immediate concerns with the client in relation to the significant decay noted to the frames together with evidence of detached timbers which were found in the courtyard.
As a result, I recommended the courtyard to not be used by the occupants until the area was made safe.
Scaffolding was erected shortly after which not only enabled me to carry out a closer inspection of the windows but also acted as a crash deck should any of the timber become loose or fall.
Why did you consider the shallow depth of gutter to be a contributory factor?
The depth of the gutter was around 10mm which during heavy period of rain was likely to overflow onto the windows.
Staining on the lead fascia suggested this had been occurring.
What depth should the gutter have been?
Typically around 50mm to prevent rainwater overspilling.
The depth of gutters is defined by factors such as:
- Roof area
- Roof pitch
- The typical amount of rainfall in that area.
How did you determine the depth of the gutter and what should this have been?
I reviewed Approved Document H which provided guidance on the calculation of the drained area taking into consideration the rainfall in that area to determine the depth of gutter.
I consulted with a drainage engineer to undertake rainwater capacity calculations on the existing system.
This confirmed the existing depth was inadequate.
What depth should the gutter have been?
Typically, a depth of 50mm to prevent water over spilling on to the angled timber below.
The new dormer roof did not require a 50mm kerb due to the vertical window position and the roof discharging to the left and right cheeks.
How did you determine the timber windows were beyond repair and needed replacement?
- The timber windows had extensive decay beyond the point which could be restored.
- The decision was made to replace them based on the poor design.
- Repair and retention would not have been a long-term solution for the client.
When is planning permission required?
If the work being carried out meets the statutory definition of ‘development’ set out in Section 55 of the Town and Country Planning Act 1990.
This is for works that will ‘materially affect’ the way the outside of the building looks.
What are the types of planning application can be made?
- Full Planning Application: Proposals for developments which are not covered by a householder application.
- Outline Planning Application: Outline planning applications are made to find out whether a development is acceptable.
- Householder Planning Application: Used for developments such as garages, alterations and extensions.
- Listed Building Consent applications: Required for alterations to, or extension or demolition of a Listed Building.
Why was a full planning application required at Winckley Square?
Any works relating to a flat requires a full planning application.
What is the timeline for planning permission?
- 8 weeks
- 12 weeks for more complex matters.
Did the LBC /Planning Permission have any conditions – what were these?
- The development must be in accordance with the approved plans.
- No materials shall be used other than those referred to on the approved plans.
- Works started no later than 3 years from the date of acceptance.
What is pre-application advice – how did you apply for this?
- Advise obtained from the Local Authority to determine the feasibility of the proposal.
- Submitted relevant information (description of proposal, proposed drawings and material specifications).
What are Building Regulations?
Building regulations ensure buildings are designed and constructed in line with set standards to ensure people’s health and safety.
When are Building Regulations required?
If the work being carried out meets the statutory definition of ‘building work’ set out in Regulation 3 of the building regulations, such as:
- Construction of a new building
- Extension or alteration of existing building
- Provision of new services or fittings such as heating systems, sanitary facilities replacement windows & doors.
What type of building regulation applications are there?
Full Plans: Plans are checked to comply with building regulations and approved before the work starts, preventing corrective works on site.
Building Notice: For works that are generally uncomplicated and the applicant has knowledge of the building regulations. The works do not require detailed drawings and building works can start within 48 hours of the local authority receiving the notice.
What did you include within the heritage statement?
The heritage statement included:
- The history of the building
- The current condition of the building
- Impact of proposed works on the historical fabric
Given that the works formed part of the modern extension that did not contribute towards the listing.
The heritage statement was proportionate considering that no parts of the original materials were to be changed.
Opt 1; you considered replacing the timber. What other advantages and disadvantages were there with timber rather than Upvc?
I considered that the timber windows would be in keeping with the local areas and existing buildings.
However, from a cost and quality perspective – timber windows often cost more than uPVC and then require further costs for maintenance.
Given the access restriction, this would not have been cost effective.
The one drawback in terms of maintenance when it comes to uPVC versus timber windows is the repairability of a timber frame. If you get significant damage to a uPVC window frame, you’re probably going to have to replace it.
With the replacement angled timber windows; How would an improved sill design be formed?
The timber windows would have been bespoke to suite the angled nature of the mansard roof pitch. (70-80 degrees)
If pre-application advice already told you that changing the windows for a different design was feasible – why would you keep the poor /angled timber design?
- This was based on cost and ultimately trying to retain the existing style from an aesthetical point of view.
- I proposed to install a built up timber kerb to prevent rainwater overspilling together with an improved sill detail to discharge rainwater efficiently.
- Further considering this option, I took into account the maintenance requirements which ultimately weren’t feasible.
What is the Role Lead Sheet Manual and why did you refer to this?
The Role Lead Sheet manual is by the Lead Sheet Association.
This provides technical advice and detailed drawings for the application of rolled lead.
This manual contains technical information and designs of both inset and protruding dormers.
The advice given is as per BS 6915: Desing and construction of lead sheet roof and wall coverings.
Why did Option 2 (windows) have a higher risk of damp penetration?
I considered the risk of water ponding to the recessed reveals (internal corner) from driving rain.
Why did you dismiss the risk of damp ingress to the inset cill?
I contacted a technical sponsor from the Lead Sheet Association who advised that if the:
- cill plate minimum of 50mm and dressed with lead.
- lead welded gusset was installed to the internal corner in accordance with the Rolled Lead Sheet Association guidance
the risk of ingress was negligible. (but ultimately there was still a risk present).
Could an internal sill not have been formed for opt 2 (windows)?
Yes, although the sill would have projected from the windows which wouldn’t have been aesthetically pleasing and may have caused potential obstructions to the occupants and a risk of collision.
Why was removing the internal sill not practical?
On inspection I noted the owner of the apartment used the cill for storage of items particularly in the bathroom and kitchen.
Chosen window design; How did you identify the u-value requirements and what were these?
Approved document L (Volume 1) table 4.3.
- Dormer cheeks to achieve a maximum U value of 0.18.
- New flat roof to achieve a maximum U value of 0.16.
- New windows to achieve a maximum U value of 1.4.
Were the u-values achieved?
Yes, the u-values for the roof were exceeded achieving 0.13 due to the insulated back plasterboard.
Do you need building regulations to install windows?
You need to comply with the thermal performance standards set out in the building regulations to install new windows.
However, if the installer is registered a FENSA certificate is provided to validate that the installer who fitted your windows or doors has complied with Building Regulations.
NOTE: FENSA is a government-authorised scheme.
What happens if no FENSA is in place?
You can apply to your local authority for a ‘Retrospective Building Regulation Compliance Certificate’.
This can take time and cost £300-£400
What Building Regulations would you consider for windows?
Part L: Conservation of Fuel and power (maximum u-value 1.4)
Part F: Ventilation – All new windows are required to have trickle vents following recent.
Part K: Protection from falling collision and impact.
What Building Regulations were applicable to the dormers?
Part A: Structure
- Construction details of the dormers.
- Building Control requested structural engineer calculations for the dormers to be obtained and included within the design.
Part C: Resistance to contamination of moisture
- Condensation control measures for the dormer roof and cheeks.
Part L: Conservation of fuel and power –
- New external walls to achieve a maximum U value of 0.18.
- New flat roofs to achieve a maximum U value of 0.16.
- New windows to achieve a maximum U value of 1.4.
- Provide insulated cavity closers at jambs, sills and reveals.
Part F: Ventilation
- To provide trickle ventilation to all new windows.
Part K: Protection from falling, collision and impact
- Windows above 800mm from ground level not in critical glazing location.
How did the insulation depth affect the design?
When determine if to use a warm deck or cold deck roof.
The warm deck construction raised the profile of the roof.
When I drew this on CAD, I considered this would not be proportional to the size of the windows.
What’s the difference between a cold roof and warm roof?
Cold Deck
- Insulation between rafters.
- Through ventilation provided above the rafters to prevent condensation.
Warm Deck
- Insulation above the roof deck.
- Vapour control layer beneath insulation to prevent condensation.
- Whole structure is insulated enhancing thermal performance.
Why did you choose a cold roof?
I considered the depth of roof required for a warm deck would not be proportional to the mansard roof pitch and would encroach the existing roof line.
Are you aware of any guidance in relation to flat roof design?
BS6229: Flat roofs with continuously supported flexible waterproof coverings - code of practice.
Recent updates: AVCL – vapour barriers and vapour control layers are now redefined as Air and Vapour Control layers as they are recognised to perform in the same manner.
States cold roofs shouldn’t be recommended, it accepts this may not always be possible. This is due to the provision of a creating a cross-ventilated void above the breather membrane.
Why did you include insulated back plasterboard to the window head?
To prevent thermal bridging.
What is thermal bridging?
Where heat can by-pass through poor thermal efficient materials or there are gaps in building materials.
This affects the thermal performance of the building.
The internal temperature to this area will be less than the better insulated surfaces causing a risk of condensation where warm internal air comes into contact with the cold surface.
How did you obtain costs for the windows?
I obtained indicative costs from a local contractor selected from my firms approved contractor list.
They were chosen based on works carried out of a similar nature.
Could you not have obtained costs elsewhere? (other than local contractor)
I considered Building Cost Information Services (BCIS) but given the specialist works to the leadwork I decided it would be more accurate to obtain costs from contractors on this occasion.
How did you present the options to the client and stakeholders?
The options analysis was detailed within my report; my covering email suggested a teams call to run through each option with the building owners.
I shared each design during this meeting explaining the pro’s and cons of each option.
Did you advise Option 3 (windows) or did the client ask for option 3?
I recommended option 3 as the best option that would complement the local area and retain the use of the internal windowsill.
Option 2 and 3 were both feasible options and it came down to the owners preference and cost for the other building owners.
You had to get listed building consent for the windows, please describe the process from application through to completion of the project?
- I engaged with the local authority in the early design stages.
- I progressed the designs in consultation with the client and stakeholders.
- I then submitted the application based on the chosen design.
- After 8 weeks I received consent for both the planning permission and listed building consent.
Is there any dispensation for VAT on works to a listed building?
I believe there are exemptions; however, advising on VAT is outside of my competence and the client assessed this with their financial advisors.
Why did you choose lead for the dormer?
- Lead is a durable material.
- Given the conservation area, lead was widely used this would have been in-keeping with the local area.
Are there any health risks associated with working with lead?
- Lead is a toxic material but only harmful if inhaled or ingested.
- The risk of inhalation arises where lead is being melted, or through breathing in dust particles contaminated with lead.
- The Control of Lead at Work Regulation 2002: Employees must be protected from lead.
