Construction Technology

Question 1

Can you name the different types of foundations?

Answer 1

• Traditional strip foundations (concrete)
• Rafts
• Pads
• Piled foundations

Question 2

Can you tell me what needs to be considered when assessing the type of foundation on a project?

Answer 2

• Nature of the soil / bearing capacity (CBR: - California Bearing Ratio)
• Moisture content
• Proximity of trees and adjacent buildings

Question 3

Why might piled foundations be required?

Answer 3

Due to the compressible nature of the soil, long piles may be required to transfer the load much deeper to stronger strata

Question 4

What would need to be considered when comparing different types of structural frame on a project

Answer 4

Building use / the proposed layout of the floor plate (i.e. warehouse or office spaces generally require open plan spaces – lends itself to portal frame

Question 5

What types of materials can be used for structural frames / talk me through these?

Answer 5

• Steel
• Concrete
• Timber

Question 6

What is the difference between CLT and Glulam

Answer 6

CLT = cross laminated timber; engineered timber with layers of wood stacked cross wise and bonded together
o Typically used: for surfaces such as walls and floors

Glulam = glued laminated timber; like CLT but the grain is aligned in the same direction
o Typically used for structural beams, columns (load bearing)

Question 7

What are the benefits of using a timber structural frame as opposed to say steel and concrete?

Answer 7

• Sustainably sourced (i.e can plant new trees)
• Lower carbon footprint (less energy required to convert wood to frame)
• Easier to work with (lighter and more forgiving in terms of site modifications / adjustments – tolerances)
• Lighter material than steel/concrete – proposed load of the building could result in cheaper foundations

Question 8

What are some of the drawbacks with a timber frame?

Answer 8

Limitations on its use – not suitable for high rise construction
o i.e poor fire performance (whereas concrete is naturally fire resistant) which would weaken structural integrity
o You would need expansive fire stopping/compartmentation etc
o Although – be aware that CLT timber can be designed to achieve fire ratings (resistance is achieved through the “charring” process of the surface)

Can be more expensive

Question 9

What are SIPS?

Answer 9

Structurally insulated panels

Question 10

If you were to build a basement, do you know what foundations are typically used?

Answer 10

• Secant piling to create a retaining structure (essentially interlocking piles, with primary and secondary piles)
• Also, contiguous piling – consist of piles arranged with a small gap between
• Properly tanked system to prevent water ingress

Question 11

What are the building regulations?

Answer 11

Statutory regulations that set standards for the design and construction of buildings

Question 12

Why are the building regulations important?

Answer 12

• To ensure the safety of a building’s occupants / users
• Provide uniformity to design and construction across all buildings within the UK (ensure minimum standards are met)

Question 13

What is part B of the building regs?

Answer 13

Fire Safety

Question 14

What is part L of the building regs?

Answer 14

Conservation of fuel and power

Question 15

You mention some modern methods of construction (MMC), can you just run me through a list of modern methods you are familiar with?

Answer 15

Modern methods of construction utilises off-site construction techniques via manufacturing (factory-produced components) – examples are:
o Modular buildings – a building constructed off-site – split into several “modules” and then assembled on site
o Systems such as SIPS (Structural Insulated Panels)

Question 16

What does BIM stand for?

Answer 16

Building information modelling

Question 17

What is the purpose of BIM?

Answer 17

Building Information Modelling is the holistic process of creating and managing co-ordinated information for a built asset

Question 18

How can BIM improve the RIBA 4 design?

Answer 18

BIM can improve co-ordination and identify any errors before they appear on site (clash detection)

Question 19

In your Forest Academy project you advise that you were required to propose a foundation detail to support the new extension floor structure, can you talk us through what you proposed?

Answer 19

I proposed that a new strip foundation be installed alongside the existing building’s traditional brick foundations. This then allowed a new dense blockwork wall to be built off of the foundation to provide support for the floor structure.

Question 20

In the same project (Forest Academy), you also advised that consideration was given to the levels of the existing and proposed DPC, can you explain how this affected your design?

Answer 20

The existing DPC levels had to be considered so that I ensured the level of the extension DPC did not breach the existing, which would result in damp issues later down the line.

Question 21

You talk about a Corporate Estate Decarbonisation Review in your submission, can you talk us through what retrofitting opportunities you recommended to the client and why?

Answer 21

• As mentioned in my submission, part of the review process involved identifying brick bonds common with cavity wall construction, following this I ascertained which cavity walls currently did not contain insulation and therefore recommended blown cavity fill insulation. In this scenario this option gave the client the most attractive pay back period for their investment.
• Where possible, I also recommended loft insulation.

Question 22

Can you describe the different types of flat roof construction?

Answer 22

• Cold roof – Insulation is positioned below the structural deck
• Warm roof – Insulation is positioned above the structural deck
• Inverted roof – Insulation is placed on top of the waterproof membrane

Question 23

For your roof replacement project at Bramford Primary School, can you advise why you recommended a warm roof construction as opposed to a cold roof?

Answer 23

• With a cold roof system, the insulation is positioned below the structural deck which means there is a risk of condensation forming should there not be adequate ventilation within the roof void.
• With a warm roof system the vapour control layer is placed below the insulation which reduces the risk of condensation forming and there is no need for providing ventilation.

Question 24

What would you consider when determining if cladding is safe?

Answer 24

• Fire engineering input is recommended for all properties above and below 18m.
• Design in accordance with Approved Document B and BS 9999. Must resist the spread of fire over walls.
• Specification of combustible materials to minimum Euroclass A2-s1.
• A modern non-load-bearing façade system has three main sections: the external cladding, thermal insulation and the backing wall. All three parts may promote fire spread.
• BR 135 assessment - Testing products in relation to combustibility.

Question 25

Can you talk about the different types of Pile foundations?

Answer 25

Two main types of pile
- Friction
- End bearing

Sub-types include
- Driven
- Bored
- Cast in-situ

Question 26

How did calculate the number of drainage outlets required for Bramford roof?

Answer 26

In this instance the number of outlets required confirmed sufficient by the roofing manufacturer, however if I were required to calculate this would refer to Approved Document H; total roof area x the rainfall intensity.