Construction Tech - Flash Cards - L2 Flashcards by Deleted Deleted

Flat roof, Lavant - Why did you specify a warm deck roof?

The existing roof was a warm deck, it is economically and practically advantageous to keep to a warm deck.

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Flat roof, Lavant - What are the benefits of a warm deck roof?

Good thermal performance, no requirement for ventilation preventing the risk of condensation build up.

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Flat roof, Lavant - What is the differences between a warm deck, cold deck and inverted roof?

Warm deck - insulation above the deck.
Cold deck - insulation between the rafters with ventilation.
Inverted - Insulation on top of the waterproof covering. (pro: waterpprofing is protectcted form mechanical / UV damage. Con: Themal briging can be a concern)

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Flat roof, Lavant - Why did the existing insulation level need to be increased?

To meet the Building regulations U-value requirement within part L (0.18 w/m2k).

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Flat roof, Lavant - What are the Part L requirements for flat, pitched roofs and roof lights?

Vol 2 table 4.1:
Flat roofs - 0.18
Pitched Roofs - 0.16
Rooflights - 2.2
Windows 1.6

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Flat roof, Lavant - What did you need to consider in relation to the flashings of the first floor windows?

That the windows would require replacement, reduction in size to ensure that the 150mm upstand requirement is achieved.

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Flat roof, Lavant - Why is a 150mm upstand required? Where is this standard from?

Protects the covering and surrounding construction. Detailed in BS 6229 (Flat roofs).

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Flat roof, Lavant - What did you specify to ensure that the flashing requirements were met?

Ensure a minimum of 150mm upstand was provided in accordance with BS 6229.

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Flat roof, Lavant - What type of flat roof replacement was installed and why?

Bauder 2 layer RMB warm roof. Existing was warm deck, tapered system required due to insufficient falls, client requirements (design guide / guarantee).

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Flat roof, Lavant - How was the existing build up of the warm deck roof constructed?

Timber deck, bitumen vapour control, cork insulation, flet covering.

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Flat roof, Lavant - What was specified for the roof replacement?

Bauder 2 layer warm deck, strip existing waterproofing / cork, retain existing VCL, apply primer to VCL, apply VCL, insulation, underlayer and capping sheet.

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Flat roof, Lavant - Why was Bauder the chosen option?

Manufacture undertook survey and specification inc conjunction with client requirements, allowed for tapered insulation. Allowed for Safe2Torch application.

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Flat roof, Lavant - What is Safe2Torch?

National federation of roofing contractors campaign to reduce the fire risk in installation using gas torches.

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Flat roof, Lavant - How much insulation was required? What is the U value?

The manufacture undertook a thermal analysis to confirm that an average of 130mm would achieve the 0.18w/m2K u-value as required in Part L (vol 2).

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Flat roof, Lavant - What regulation is adhered to for creating flat roof falls?

BS6229:2018, all flat roofs should be designed with a fall of 1:40 to ensure a finished drainage fall of 1:80 is achieved as required by the building regulations.

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Flat roof, Lavant - What Approved documents did you need to refer to for this project?

Part A - Structure, For consideration of additional loading.
Part B (vol 2) - Fire, Resisting fire spread over roof coverings.
Part C - Site preparation and resistance to contaminants and moisture.
Part H - Drainage & waste disposal, Drainage of rainfall to the flat roof.
Part K - Protection from falling, collision & impact, Fall protection (if required)
Part L - Conservation of fuel and power, U-values

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Flat roof, Lavant - What standards would you refer to for lead flashing installation?

The Lead Sheet Training Academy & BS 6915, code of practice for installing lead sheets.

Flat roof, Lavant - How is a lead flashing installed?

Mortar joint is raked out a min 25mm deep. Mortar joint is a min 150mm above the finished roof level. Lead sections ate 1.5m max in length. Lead sections overlap 100mm with one another. Lead is fitted in mortar joints with lead packers and sealed with a flexible sealant. Patination oil applied.

Flat roof, Lavant - What guidance did you consider when specifying the coverings?

RICS Guidance on Flat Roof Coverings - Comparison of material types (benefits / limitations).

BS6229

Windows, Castlewood - What approved documents did you need to refer to for this project?

Part A - Structure, If a new opening is being formed.
Part B - Fire, Glazing against escape routes.
Part F - Ventilation, Requirements of ventilators on windows.
Park K - Protection from falling, collision & impact, impact and design of glazing.
Part L - Conservation of fuel & power, U values 1.6
Part M - Access to and use of buildings, Window opening accessibility, door standards.
Part O - Overheating, Limiting solar gains.

Windows, Castlewood - What statutory approvals are applicable for window replacements?

Building control approval,
Planning permission - Subject to design changes,
Listed building consent - if building is listed.

Windows, Castlewood - What is cold bridging?

An area or a component of an object which has a higher thermal conductivity than the surrounding materials, creating a path of least resistance for heat transfer

Windows, Castlewood - How is an aluminium frame thermally broken?

By having neither the internal or external section of aluminium connected to one another. Thermal break made from PVC. Some frames have additional insulation within the frames.

Windows, Castlewood - What is the benefit to thermally broken aluminium vs timber?

Timber is a good insulator, however without regular maintenance timber can be affected by the elements causing degradation. Aluminium has a good durability with a very low requirement for maintenance

Windows, Castlewood - How would you determine where a window is placed within a cavity wall?

Refer to BS 8213-4 - code of practice for installation of windows. Rear face of replacement frame is sat behind the rear face of external skin by 25mm or more.

Windows, Castlewood - How is a window fixed within the wall?

Refer to BS 8213-4 - code of practice for installation of windows. At centres not exceeding 600mm, no further than 150mm from each corner. Joint sealed with sealant.

Windows, Castlewood - How would you determine what ventilation is required?

Use Building Bulletin 101 and Approved Document Part F (Ventilation) - Ventilation through background ventilators is detailed within section 3. Existing windows with should not be made worse, windows without should meet requirements set out in the AD.

Windows, Castlewood - What are the building bulletins and provide an example of one?

Building Bulletins are produced by the DfE and offer guidance on a range of subjects, from whole school design schedules to detailed engineering specifics. Building Bulletin 101 on ventilation & thermal comfort.

HDP - What fabric upgrades did you identify?

Cavity wall insulation, loft insulation, window & door upgrades.

HDP - What guidance did you use for specification of insulation?

Part C - Requirements of cavity fill. Part L for u-value and limiting u-value requirements. Manufacturer specification tools i.e. Kingspan.

HDP - What U-values where required to be achieved for roof insulation and Windows?

Flat roof - 0.18 w/m2k Pitched roof - 0.16 w/m2k Windows & doors - 1.6 w/m2k

HDP - What U-values where required to be achieved for cavity wall insulation?

Part L - limiting values - threshold is 0.70 w/m2k

HDP - What products were specified for thermal insulation?

Knauf loft roll 44 - manufacture specified depth to achieve U-value. ThermaBead - Bonded bead system, BBA approved.

HDP - What factors and surveys were considered prior to CWI installation?

Cavity depth, cavity condition, brickwork / pointing condition, evidence of moisture entering the cavity, ensure no cavity bridge is made.

HDP - What M&E upgrades did you suggest?

Control modifications, LED lighting, replacement of gas boilers with ASHP, PV, solar thermal.

HDP - How does an ASHP work?

Absorbs heat from outside air into a refrigerant, pump compresses liquid increasing the temp, condenses back to a liquid releasing the stored heat.

HDP - What legislation is there around heat decarbonisation?

Climate change act 2008 - UK legally binding target. The Paris Agreement 2015 - Legally binding treaty to reduce temp rises.

HDP - What is cold bridging?

A component of high thermal conductivity extending through another element providing a passage for heat transfer.

How would you determine the construction type of a building is cavity wall?

Age of the building built after 1920s, identify from loft space, EPC, composition of internal and external brickwork, undertaking bore-scope survey.

What are some benefits and limitations of RBM?

Benefit: durable, long lasting, cost effective, withstand walking traffic. Limitation: Crack or blister, some systems are expensive.

Flat roof, Lavant - Why did you not look at installing an alternative covering method such as EPDM or a liquid coating?

EPDM - Shorter lifespan than RBM, can be punctured easily, not good for walking on, blown debris / hail can puncture it, easily UV damaged. Liquid coatings - Skill requirement for ensuring a consistent coating of system is applied, weather needs to be dry for duration for install.