02 Construction Design

Question 1

What should you consider if your client was planning a roof conversion of a two storey house?

Answer 1

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Question 2

In respect of the Building Regulations, what would you have to take into account when constructing a single storey flat roof extension with a bathroom?

Answer 2

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Question 3

An extension to an existing terraced house requires new foundations. Outline what must be considered to design the new foundations and their interface with the surrounding properties.

Answer 3

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Question 4

What is a U-value?

Answer 4

1. A U-value is a measure of heat loss in a building element
2. The higher the U-value, the worse the thermal performance

Question 5

How is a U-value calculated?

Answer 5

U-value = 1 / (ΣR + Ri + Ro)

• Ri = thermal resistance of inside surface
• Ro = thermal resistance of outside surface
• ΣR = sum of the thermal resistances of all other building components
• NB: R = d / k (thickness of component / thermal conductivity of that component)

The conventions for calculating U-values are established by BR 443 (Conventions for U-value calculations)

Question 6

What are the required U-values for walls, floors, roofs and windows of new domestic dwellings?

Answer 6

1. Roof - 0.20 W/(m².K)
2. Wall - 0.30 W/(m².K)
3. Floor - 0.25 W/(m².K)
4. Windows, roof windows, curtain walling and pedestrian doors - 2.00 W/(m².K)

Question 7

What are the required U-values for walls, floors, roofs and windows of new buildings other than dwellings?

Answer 7

1. Roof - 0.25 W/(m².K)
2. Wall - 0.35 W/(m².K)
3. Floor - 0.25 W/(m².K)
4. Windows, roof windows, curtain walling and pedestrian doors - 2.20 W/(m².K)

Question 8

What are the U-value requirements in existing buildings?

Answer 8

Existing buildings require reasonable provision for U-values in newly constructed thermal elements (such as those constructed as part of an extension) as well as upgrading retained thermal elements

Refer to tables in Part L1B for dwellings and Part L2B for non-dwellings

Question 9

What requirements would you have to be aware of when adding insulation between rafters?

Answer 9

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Question 10

What are the ventilation requirements under the Building Regulations?

Answer 10

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Question 11

What factors might affect the choice of material for internal partitions?

Answer 11

1. Height
2. Fire resistance
3. Thermal properties
4. Noise transfer
5. Fixings (e.g. grab rails)
6. Likelihood of damage
7. Cost
8. Installation time

Question 12

What factors would you consider when specifying a floor finish?

Answer 12

1. Room use
2. Hygiene (e.g. vinyl in toilets)
3. Slip resistance - R-rating, R9 (worst) - R13 (best)
4. Fire spread
5. Acoustic qualities
6. Static
7. Indentation
8. Level of sub-floor (may need to apply a levelling screed)
9. Moisture content in sub-floor (may need to provide a DPM)

Question 13

What are the sound insulation requirements for different building/room types?

Answer 13

General performance requirements are usually set by the client, however there are certain specific building types where the requirements are set:

1. Schools - Building Bulletin 93: ‘Acoustic design of schools’
2. Hospitals - Heath Technical Memorandum (HTM) 08-01: ‘Acoustics’
3. Residential - Approved Document E: ‘Resistance to the passage of sound’
4. General guidance - BS 8233:2014 ‘Guidance on sound insulation and noise reduction for buildings’

Question 14

Name some of the main materials that have been banned from use in construction.

Answer 14

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Question 15

What is the maximum riser and tread recommended for stairs?

Answer 15

See Approved Document K

• Risers can be between 150-220mm (depending on use)
• Treads can be between 220-400mm (depending on use)

Question 16

What is FENSA and what is its purpose?

Answer 16

1. Fenestration Self-Assessment Scheme (FENSA) is the government authorised Competent Persons Scheme for replacement windows, doors and rooflights in England and Wales (domestic properties only)
2. Enables companies to self-certify compliance under the Building Regulations without the need for a separate Building Control assessment

Question 17

What guidance is available for designs within schools?

Answer 17

1. Building Bulletin 93 - Acoustic design of schools
2. Building Bulletin 100 - Design for fire safety in schools
3. Building Bulletin 103 - Area guidelines for mainstream schools (details space requirements for schools based on number/age of pupils and activities)
4. Department for Education - Advice on standards for school premises (details number of toilets/washing facilities, medical room requirements, acoustics, lighting)
5. School Washroom Guidelines (details number and dimensions for washroom facilities in schools)

Question 18

Where would you go to find out if a material was banned from use in construction?

Answer 18

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Question 19

What factors should be considered when specifying sound insulation?

Answer 19

1. Privacy requirement for the source room
2. Noise generation of the source room
3. Noise sensitivity of the receiving room

Once these factors are known, tables in the appropriate guidance documents can give the sound insulation performance required