Construction technology

Question 1

What is the build up of a flat cold roof?

Answer 1

Plasterboard, vapour control layer, roof structure, insulation in between, deck, covering. [Part H].

Question 2

How did you prevent potential problems from a cold roof?

Answer 2

Ensure there’s enough ventilation throughout the roof.

Question 3

a) Where would you expect to see a cavity barrier?
b) Why?

Answer 3

a) Between walls, floor and around windows and doors [wall cavity].
b) Prevents the spread of fire and smoke to other areas and floors.

Question 4

What would you need to consider when constructing a partition wall?

Answer 4

• AD B: Need to be fire rated i.e. a protected corridor? [12.5mm plasterboard, fire doors].
• AD M: min 1.2m wide.
• Installing deflection heads.

Question 5

What is a deflection head?

Answer 5

A detail at the top of partitions to allow for structural movement of the floor/roof above.

Question 6

What type of sand is required for lime mortar?

Answer 6

Washed sharp sand.

Question 7

What’s the difference between hydraulic and non-hydraulic?

Answer 7

Hydraulic is stronger, non-hydraulic is more flexible.

Question 8

When was cement mortar first used?

Answer 8

Around the 1800s.

Question 9

What causes spalling brickwork?

Answer 9

• Freeze-thaw.
• Water ingress.
• Putting cement mortar on lime mortar (water escapes through brick face).

Question 10

You mention artificial slates, how do you recognise them?

Answer 10

They have straighter and more complete finish compared to natural slates which are rougher.

Question 11

What are the limitations of a VRF system?

Answer 11

You can get leaks.

Question 12

Note: Con Tech - 18-20 Tileyard Road.
- TDD.
- Water staining.
- Gap between asphalt and bitumen felt capping.
- Redress upstand detail to include lead apron or install flashband.

Question 13

a) What is an Initial Notice?
b) What’s the alternative to using an Inital Notice for Building Regulations?

Answer 13

a) Notify local authority that construction has started and BCA is being used.
[Local authority has 5 working days to review and reject otherwise it passes]
b) Full Plans Application [LABC route].
[Initial Notice is for BCA route].

Question 14

Note: Con Tech - Beckton Gateway Retail Park:
- TDD (pre-acq).
- Captured construction forms and building fabric.
- Recommended investigating insulation spec within insulated render [fire safety].
[- Euroclass B required (insulated render met this)]

Question 15

Beckton Gateway Retail Park: Where would you find the specification of the insulated render?

Answer 15

• O&Ms.
• Manufacturer.
• Client.

Question 16

Timber Mill Way: What did you report to the client?

Answer 16

• Missing intumescent strips and smoke seals.
• Gaps in doors too big [10mm].

Question 17

Timber Mill Way: What did you recommend as remedial works?

Answer 17

• Retrofit strips and sealant.
• Ease and adjust doors to reduce gaps to appropriate levels.

Question 18

Timber Mill Way: What are the required gap measurements?

Answer 18

Gaps:
- Top and sides: <4mm.
- Bottom: <8mm [where there’s no threshold seal] or <3mm [if smoke seal required].

Question 19

Timber Mill Way: Are you qualified to recommend remedial works/specifiy fire door works?

Answer 19

• I can specifiy works/remediation.
• Sign off must be done by BCA if a new door [certified installer provide certificates demonstrating proper installation which a BCA can use as evidence i.e. BM TRADA, Certifire]

Question 20

18-20 Tileyard Road: What levels should the covering, apron and capping [lengths] be?

Answer 20

• Upstand [asphalt]: min 150mm above roof level.
• Apron [lead]: min 75mm over covering.
• Lead laid in max 1.2m lengths [to allow for movement].

Question 21

18-20 Tileyard Road: What repairs did you recommend?

Answer 21

• Upstand [asphalt]: min 150mm above roof level.
• Apron [lead]: min 75mm over covering.
• Replace old bitumen felt capping with new.

Question 22

18-20 Tileyard Road: What guidance did you refer to for the repair?

Answer 22

BS 6229 [gives measurements i.e. 150mm upstand and 75mm apron].

Question 23

18-20 Tileyard Road: What did you consider when advising the client?

Answer 23

• Cost [asphalt upstand and lead apron vs flashband].
• Lifespan of remediation.
  [- Measurements [150mm, 75mm].]

Question 24

18-20 Tileyard Road: What can cause cracking of asphalt and bitumen felt?

Answer 24

• No movement joints.
• Freeze-thaw.
• UV degradation.
• Age.

Question 25

18-20 Tileyard Road: a) What grade was the lead apron? b) Why did you specify this?

Answer 25

a) Grade 4 (1.8mm). b) Followed BS 12588 which stated that this was the appropriate code of lead for this application.

Question 26

18-20 Tileyard Road: What flat roof tests did you undertake aside from visual inspections?

Answer 26

- Damp meter on timber structure (normal reading - no rot). - Core sampling [didn't do this but is an option]. [18-20% indicates moisture is present could lead to issues, over 20% considered high].

Question 27

Timber Mill Way: What regulations or guidance did you refer to when advising the client?

Answer 27

- AD B [regulations to comply with]. - BS 8214 [how to install and maintain to comply with regs].

Question 28

Timber Mill Way: What is an 'S' fire door?

Answer 28

Prevents smoke as well as fire. [FD30S - prevents fire and smoke] [FD30 - prevents fire only]

Question 29

Timber Mill Way: a) Did the door have any kitemarks? b) How else did you know it was a fire door?

Answer 29

a) Yes. b) Door was 45mm thick [FD30].

Question 30

Timber Mill Way: a) Did you need building regs approval following the installation of intumescent strips and smoke seals? b) What if the door wasn't a fire door originally and you retrofitted the strips and seals?

Answer 30

a) No, as it's repair/maintenance (door already a fire door) [kitemarks, 45mm thick - standard doors are 35mm]. b) Replacement of the fire doorset would be needed [doorsets need to be certified as they're tested - standard doors aren't].

Question 31

Beckton Gateway Retail Park: a) What was the Euroclass rating of the insulated render? b) What did it need to be?

Answer 31

a) Euroclass B. b) minimum Euroclass B.

Question 32

Beckton Gateway Retail Park: You mention checking the insulated render specification to ensure it complies with relevant standards. What are these standards?

Answer 32

- AD B [external walls must limit spread of fire]. - Euroclass rating [B rating required as stated in AD B].

Question 33

Beckton Gateway Retail Park: Can you talk me through the buildup of the building envelope?

Answer 33

- Steel portal frame. - Built up cladding to roof and elevations. - Brickwork and insulated render to standalone structures.

Question 34

Beckton Gateway Retail Park: Who did you recommend to undertake further investigation?

Answer 34

Said I would do it but needed O&M information from the client.

Question 35

Beckton Gateway Retail Park: What statutory documents did you review?

Answer 35

None, not available before inspection.

Question 36

CBXII: What are the key requirements under AD K regarding safety glazing, and how did these influence your recommendations?

Answer 36

Glazing below 1500mm from floor level needs safety glazing [glazing adjacent to a door - within 300mm]. [800mm rule is for windows]

Question 37

CBXII: What factors did you consider when advising the client on retrofitting safety film versus full glazing replacement?

Answer 37

- Condition of glazing. - Cost. - Short-term [10-15 years].

Question 38

CBXII: What are the characteristics safety glazing offers?

Answer 38

- Less risk of injury if it breaks. - Cost [cheap]. - Time [quick to install].

Question 39

CBXII: What are the benefits and drawbacks of safety film versus replacement?

Answer 39

Safety film: - Cost [cheaper]. - Time [quick]. - Short-term [maintenance]. Replacement: - Better performance. - Long-term. - Expensive.

Question 40

CBXII: Why are kitemarks important?

Answer 40

Provides evidence glazing meets building regs [AD K].

Question 41

CBXII: What issue did you identify with the glazing during the survey?

Answer 41

- Glazing below 1500mm limit. - Didn't comply with building regs [AD K]. [- No kitemarks.]

Question 42

CBXII: What are the limitations of retrofitting safety film from a compliance and durability perspective?

Answer 42

- 10-15 years [safety glazing 30+ years]. - Peel or scratch [replacement may be required]. - No fire resistance.

Question 43

CBXII: What does AD K say about retrofitting safety film?

Answer 43

- Details performance criteria. - Break safely [glass should]. [- Resist impact without breaking] [- Be protected from impact (something prevents occupants striking the glass)]

Question 44

18-20 Tileyard Road: a) How would you assess the remaining service life of the asphalt flat roof? b) How did this affect your advice?

Answer 44

a) - Visual inspection. - Cracking and blistering to surface. b) - Wasn't deteriorated enough, so repairs tonupstand only. - Would propose full replacement in addition to upstand repairs if at the end of it servicable life.

Question 45

Timber Mill Way: What is a nominal and notional fire door?

Answer 45

Nominal: - Typically fire resistant but not certified [i.e. solid timber]. - Can be upgraded to comply [strips and seals, good fit etc]. Notional: - Typically not fire resistant. - Needs replacing.

Question 46

Timber Mill Way: a) Can regular contractors remediate fire doors? b) Would Building Regulations approval be required following completion of the repairs?

Answer 46

- AD B states competent contractor only required not third-party approved installer. - No, strips and seals installation considered an upgrade not material alteration.

Question 47

Timber Mill Way: How would the fire doors be adjusted to close the gaps?

Answer 47

- Adjust hinges. - Use packers behind hinges.

Question 48

18-20 Tileyard Road: a) What would you expect to be present at the bottom of the junction? b) What would you recommend be installed here to account for thermal movement between the asphalt and enclosing wall?

Answer 48

a) Concave fillet. b) Slip sheet.