Construction technology

Question 1

What detail is included for 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

Where would you expect to see a cavity barrier and why?

Answer 3

• Between walls, floor and around windows and doors [wall cavity].
• 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 M: min 1.2m wide.
• Does it need to be fire rated i.e. a protected corridor? [12.5mm plasterboard, fire doors].
• 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

Langley Quay: Explain the instruction in more detail and what you advised?

Answer 6

• Office refurb.
• Two options - one lower spec, one higher spec.
• £60k more, 4 weeks longer.

Question 7

Langley Quay: What was included in the higher spec that wasn’t in the standard spec?

Answer 7

Option 1:
- Retain suspended ceiling.
- Retain floor covering.
- Retain partitions.
Option 2:
- New ceiling.
- New floor covering.
- Remove partitions (open plan).

Question 8

Langley Quay: What was the impact of the different design solutions?

Answer 8

Lower spec:
- Short-term investment.
Higher spec:
- Longer-term investment.
- £60k more, 4 weeks longer.

Question 9

Langley Quay: Any amendments/additions to the MEP?

Answer 9

Undertook validation of existing M&E – ended up retaining it all.

Question 10

Langley Quay: Any consideration towards improving EPC rating? What advice did you provide to achieve this?

Answer 10

• Yes, upgraded to a B rating from a C rating.
• Advised installing LEDs and PIRs as property was close to a B rating and this would likely achieve this – energy consultant advised for certainty.

Question 11

Campden Hill Towers: Please explain in more detail the defects identified here. What did you visually inspect?

Answer 11

• Pre-cast concrete panels were deteriorating.
• Spalling concrete.

Question 12

Campden Hill Towers: What was the likely cause of the defect?

Answer 12

The steel fixings holding the panels up were expanding and damaging the panels (risk of falling debris).

Question 13

Campden Hill Towers: What was your immediate recommendation to the client following your inspection?

Answer 13

• Erect crash decking to protect the pedestrians below.
• In-depth survey to be undertaken (abseil).

Question 14

Campden Hill Towers: How did you recommend the defect diagnosis works proceed?

Answer 14

Survey by abseil due to building height and surrounding area.

Question 15

Campden Hill Towers: How was disrepair assessed?

Answer 15

• Initial survey from ground level.
• In-depth survey undertaken by specialist.
• Report produced which I reviewed.

Question 16

Campden Hill Towers: a) What repair works were ultimately recommended?
b) How long was the programme for this?

Answer 16

a) Remove existing cladding and replace with new.
b) 6 months.

Question 17

How did you determine there was lime pointing at Windsor Walk?

Answer 17

• Victorian property.
• Solid brickwork wall (lime typically used).
• Sandy colour - cement mortar is grey.

Question 18

What type of sand is required for lime mortar?

Answer 18

Washed sharp sand.

Question 19

What’s the mix for lime?

Answer 19

1:3
Lime to sand.

Question 20

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

Answer 20

Hydraulic is stronger, non-hydraulic is more flexible.

Question 21

When was cement mortar first used?

Answer 21

Around the 1800s.

Question 22

What causes spalling brickwork?

Answer 22

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

Question 23

You mention artificial slates, how do you recognise them?

Answer 23

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

Question 24

What type of air conditioning was specified on Windsor Walk?
Why was this system used?

Answer 24

• VRF (Variable Refrigerant Flow).
• More energy efficient.
• Doesn’t need ductwork like a VAV (Variable Air Volume) system.

Question 25

What are the limitations of a VRF system?

Answer 25

You can get leaks.

Question 26

Note: Con Tech - Campden Hill Towers. - Project. - £150k. - Cladding remediation. - Time and cost implications: £60k more, 4 weeks less. Cost was more expensive to remove panels but better longevity than wrapping.

Question 27

Note: Con Tech - Langley Quay. - Project. - £200k. - Remove tenant chattels, refurb of office. - Two design options - one high spec (long-term), one low spec (short-term - retain existing ceilings, partitions and floor covering).

Question 28

a) On Campden Hill Towers you completed works to a residential tower block. What did you have to issue to commence works? b) Why is this required? c) Do you know of any legislation relating to this?

Answer 28

a) Section 20 notice. b) Landlords to notify leaseholders of major works where costs exceed £250 per leaseholder. c) LTA 1985.

Question 29

Bricket Road, St Albans: What is an Initial Notice?

Answer 29

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]

Question 30

Travelodge, Gray's Inn Road: Talk me through the build up of the external wall system.

Answer 30

- Render. - EPS insulation (expanded polystyrene). - Sheathing board. - LSF. - Void [cavity barrier missing]. - Vapour control layer. - Plasterboard.

Question 31

Travelodge, Gray's Inn Road: Do hotels need to comply with the BSA 2022?

Answer 31

- They do, but are not classed as HRBs. [Care homes, hospitals, prisons aren't HRBs either as they typically have their own safety procedures].

Question 32

Campden Hill Towers: What were the different time and cost implications?

Answer 32

Removal: - £60k more. - 4 weeks less. [Removed panels using a pulley/winch to lower to ground floor]

Question 33

Campden Hill Towers: What happened to the structure when the cladding was removed?

Answer 33

The structure beneath was a concrete frame so it was temporarily left exposed while the panels were removed.

Question 34

Bricket Road, St Albans: What design requirements did you consider?

Answer 34

- Fit-out - kitchens, offices. - M&E layout. - Fire stopping locations. - Partitions.

Question 35

Langley Quay: What were the different time and cost implications for the two options?

Answer 35

High spec: £60k more, 4 weeks longer.

Question 36

Travelodge, Gray's Inn Road: What was the Euroclass rating of the insulation?

Answer 36

Euroclass C (EPS insulation).

Question 37

Bricket Road, St Albans: You said you reviewed an Initial Notice as part of the LtA. What's the alternative to using an Inital Notice for Building Regulations?

Answer 37

Full Plans Application [LABC route]. [Initial Notice is for BCA route].

Question 38

Bricket Road, St Albans: For the LtA review you say you reviewed fire stopping locations. What would you refer to to find out fire stopping locations?

Answer 38

- Fire strategy plan. [- As-built drawings. - O&Ms.]

Question 39

(Follow on from Bricket Road mention of Initial Notice and ensuring compliance with Building Regulations): What is the building control process for non-HRBs?

Answer 39

- BCA or LABC route. - Initial Notice or Full Plans application. Submit documents to BCA/LABC: - Proposed and existing plans. - SoW. - Services drawings (M&E). - Fire strategy plans. [- Structural and energy calculations.] [- Site plan.]

Question 40

(Follow on from Bricket Road mention of Initial Notice and ensuring compliance with Building Regulations): What is the building control process at the end of a project for non-HRBs?

Answer 40

- Final inspection. - Provide documents for review i.e. drawings and test certificates [to BCA]. - Final certificate.

Question 41

Travelodge, Gray's Inn Road: What are AD B requirements for cavity barriers?

Answer 41

Placed: - At wall and floor junctions. - Around windows and doors. - Between demises. Fire resisitance: - 30 mins [resistance for fire and smoke] [and 15 mins limit of temperature - fire insulation]

Question 42

Campden Hill Towers: What are the implications of removing the cladding to a building? How was this to be mitigated?

Answer 42

- Exposes concrete frame [acceptable short-term but need weathertightness long-term]. AD L: - Thermal performance (U-values) [can't reduce only match or improve]. - Airtightness [can't reduce only match or improve]. - Moisture [vapour control layer and ventilation must be considered].

Question 43

Travelodge, Gray's Inn Road: How did the building materials interact inadequately?

Answer 43

- No cavity barriers > fire hits EPS insulation directly which is combustible [Euroclass C]. [If they say 'but doesn't the sheathing board provide fire resistance?' say it does but there were gaps in this instance]

Question 44

Travelodge, Gray's Inn Road: a) Was this an FRAEW? b) What's the difference between an FRAEW and an EWS1 form?

Answer 44

a) Yes. b) - FRAEW: Provides risk rating and recommendations [for remediation]. - EWS1 form: Assesses financial risk [for valuers].

Question 45

Campden Hill Towers: What is the Section 20 process?

Answer 45

3 stages: - Notice [of Intention to complete works] - 30 day consultation period. - Provide estimates - 30 day consultation period. - Notice of chosen contractor [only if not cheapest].