Technical - Construction Technology & Environmental Services

Question 1

What is substructure and superstructure of a building?

Answer 1

These are the main two components of a building.

The substructure of a building is that which site below the ground level and its purpose is to transfer the load of the superstructure through the foundations and onto the soil.

The superstructure is the structure of the building which site above the ground level and it creates the frame for the purpose of the building including floors, elevations, columns and roof.

Question 2

Name some different construction methods?

Answer 2

Traditional / Conventional Construction
Such a Brick and Blockwork and Steel whereby fabrication, assembly and construction are done on site.

Modern Method of Construction (Off Site)
- Timber Frames
- 3D Volumetric Construction
- Precast panels

Question 3

What is the RIBA Plan of Works?

Answer 3

The RIBA Plan of Work is a model for the design and construction phases of buildings. It was updated in 2020 since its last update in 2013.

The model separates the construction and occupation of a building into 8no. stages.

Stage 0 – Strategic Definition
Stage 1 – Preparation and Brief
Stage 2 – Concept Design
Stage 3 - Developed Design
Stage 4 – Technical Design
Stage 5 – Construction
Stage 6 – Handover and Close Out
Stage 7 – In Use

Question 4

Can you describe a type of traditional construction and its benefits?

Answer 4

Cast in-situ concrete using formwork:
Flexible, cost-effective, easy to transport.

Question 5

Can you describe a modern method of construction and its benefits?

Answer 5

Off-site manufacturing:
Faster construction, QA products, less waste of materials.

Question 6

You mention historic construction methods, can you describe some to me?

Answer 6

Pre-18th Century Box and Cruck Timber Frames with Thatched Roof design

Solid masonry with shallow footings.

Question 7

What are O&Ms?

Answer 7

This stands for Operation & Maintenance manuals.
Each building should have an O&M manual and it should contain details and plans on the as built construction, subsequent alterations and salient H&S documentation such as FRA and Asbestos Registers

Question 8

How do you consider EPC in building design?

Answer 8

Energy efficiency of design and materials.
Insulation in cavities, LED lighting, PIR sensors, installation of solar panels, thermal performance of elements.

Question 9

How would you assess the design life of building elements?

Answer 9

• British Standards EN 1990-1999 provides indicative design lives for structures.
• Manufacturer’s specification sheets should give details on design lives of materials.
• BCIS Life Expectancy of Building Components Guide

Question 10

What factors can impact the anticipated design life of a building component?

Answer 10

Environmental factors e.g. rain, wind, temperature fluctuations, pollution, solar radiation
Maintenance throughout the lifespan
Intensity of use e.g. increased loadings

Question 11

Kings Road, Brighton
(Filler Joist Floor)

What was the construction of the building?

Answer 11

The superstructure comprised a reinforced concrete frame.

Question 12

Kings Road, Brighton
(Filler Joist Floor)

What is a Filler Joist (Clinker) Floor?

Answer 12

A filler joist floor is an early form of reinforced concrete floor slab construction used commonly between the 1880s – 1920s. Iron or Steel ‘I’ Beams were spaced 0.6-1m apart and in-filled with lightweight concrete which often including the fines left over from blast furnaces. The load was applied to the concrete and transferred the ‘I’ Beam joists. Used as it was thought to provide fire protection.

Question 13

Kings Road, Brighton
(Filler Joist Floor)

What issue is known to affect Filler Joist (Clinker) Floors?

Answer 13

Not the structural concept but the lack of corrosion protection offered to the metal joists.

The concrete mix containing unburnt coal or coke breeze is high in sulphur. When moisture is present the sulphur through chemical process produce sulphuric acid which can attack the steal causing corrosion and expansion. Leading to failure of the floor.

Question 14

Kings Road, Brighton
(Filler Joist Floor)

What is the risk of a Filler Joist Floor?

Answer 14

Expansive corrosion can lead to the blowing and cracking of the concrete infill and ultimate failure of floor slab construction.

Question 15

Kings Road, Brighton
(Filler Joist Floor)

How would you identify Filler Joist Floor and how would you know if it was defective?

Answer 15

Distinctive underside of the ‘I’ beams with concrete infill between, if not plastered/ Visual inspection can identify expansive rusting of the beams and blowing and cracking of the concrete cover and infill. These cracks are usually found on the top, long cracks following the joists/beam lines.

Question 16

Kings Road, Brighton
(Filler Joist Floor)

What is the risk of a Filler Joist Floor getting wet?

Answer 16

The reaction of moisture with the clinker concrete results in the product of sulphuric acid combustion products and unburnt coal in the clinker concrete; due to the porosity/and lack of corrosion protection of the concrete the acid has a corrosive effect on the steel joists.

Question 17

Kings Road, Brighton
(Filler Joist Floor)

How would you test the condition of the concrete?

Answer 17

Visual inspection
Test floor loads/physical opening up

Question 18

Kings Road, Brighton
(Filler Joist Floor)

What are other forms of remedial works?

Answer 18

Expose the steel beams, remove the rust and treat with a protective paint coating or cathodic protection.

Question 19

Kings Road, Brighton
(Filler Joist Floor)

How would test if the steel is corroding?

Answer 19

• Physical opening up

Non-destructive (Specialist)
* Infrared thermography
* Resistivity and hygrometry
* Linear polarisation resistance (LPR)

Question 20

Kings Road, Brighton
(Filler Joist Floor)

You reference resin injection within your example as a form of remedial repair, can you explain this?

Answer 20

Yes, I am referring to a form of specialist repair which would only be specified following the findings of a structural engineer’s report.

This is early preventative measure. The specific method is a type of vacuum injection whereby the voids from the concrete infill around the steel ‘I’ beam are injected with a resin to consolidate the clinker concrete providing encapsulation minimising the risk of future corrosion.

Question 21

Gracechurch Street, London
(R22 Refrigerent)

What is a R22 Refrigerant?

Answer 21

It is a HCFC (Hydo-Chloro-Flouro-Carbon) type of heating/cooling gas refrigerant used in air conditioning units.

It was banned in new units in 2004 and then banned further in 2015, preventing top-up the air conditioning unit. The substance was banned as it is an ozone depleting substance.

Question 22

Gracechurch Street, London
(R22 Refrigerent)

What are the options?

Answer 22

A conversion of the unit to use a drop in replacement such as R417A. But the engineer advised me it was not feasible to do so. Instead, replacement equipment using R410A refrigerant should be installed which is more efficient.

Question 23

Beach Avenue, Barton on Sea
(Flat Roof Repair vs Replacement) Mineral Felt Roof

Describe how you would go about inspection of a flat roof?

Answer 23

Gather any available information about the building, including details of any previous issues and repairs on the roof. Make arrangements for access and prepare necessary RAMS. Identify the age of the roof, period of defect, when does it leak (consistently or times of heavy rainfall), does water pond, what is the use of the are directly below the roof. Carry out a visual inspection during or after rainfall.

Question 24

Beach Avenue, Barton on Sea
(Flat Roof Repair vs Replacement) Mineral Felt Roof

When considering the remedial works to the flat roof, what did you consider?

Answer 24

The age and condition of the roof covering, the extent of the defect, the cost involved with repairs, the use of the area below the roof and any disruption associated with repairs.

Question 25

Beach Avenue, Barton on Sea
(Flat Roof Repair vs Replacement) Mineral Felt Roof

What are the different types of flat roof?

Answer 25

Cold roof – insulation below the roof deck (leads to thermal bridging along the roof joists).

Warm roof – insulation above the roof deck (adds height to the roof so not suitable for balconies / extensions where roof decks are in use).

Inverted roof – insulation lies above the waterproofing membrane and is weighed down with ballast or paving slabs (protects the membrane but could lead to build up of moisture).

Question 26

Beach Avenue, Barton on Sea
(Flat Roof Repair vs Replacement) Mineral Felt Roof

What was the roof construction?

Answer 26

A warm deck construction.

Question 27

Beach Avenue, Barton on Sea
(Flat Roof Repair vs Replacement) Mineral Felt Roof

What did you identify to determine it was in poor condition?

Answer 27

I identified cracking, blistering and crazing in several locations. I also identified pooling water as well as poor termination details around penetrations and rooflights, allowing water ingress.

Question 28

Beach Avenue, Barton on Sea
(Flat Roof Repair vs Replacement) Mineral Felt Roof

Why did you give the advice for full replacement?

Answer 28

I provided this advice as it best suited my Client interest in the building. Since they were seeking to acquire the freehold interest in the building their intentions were long term. Therefore, it was best practice to advise a long term and robust repair.

Question 29

Beach Avenue, Barton on Sea
(Flat Roof Repair vs Replacement) Mineral Felt Roof

What was an alternative remedy?

Answer 29

Patch repair with single ply system/liquid applied system

Overcoat with a liquid applied system

Question 30

Beach Avenue, Barton on Sea
(Flat Roof Repair vs Replacement) Mineral Felt Roof

On this example who would the responsibility of the cost of the repair fall to, would your Client burden this cost or push it as part of the negotiations?

Answer 30

My Client was seeking to obtain the Freehold interest, the premises was currently let to a Tenant. Therefore, they would be obtaining the rights and obligations of the Landlord under the current lease. As the current lease was let on a Internal Repair and Insuring basis. These costs were allocated to the my Client as the Landlord under the terms of the lease following my review.

However, this is outside of my competency to advise my client any further than the facts of the condition and subsequent cost estimations for negotiations. If this was a request of theirs, I would advise they speak to their Solicitor and Agent.

Question 31

Beach Avenue, Barton on Sea
(Flat Roof Repair vs Replacement) Mineral Felt Roof

What consideration to any compliance would you have to consider when undertaking roof repair works?

Answer 31

I would have to be aware if the works would trigger consequential improvements under Part L of the Building Regs.

When a building is renovated, the work should include improvements to the building’s energy performance, such as upgrading insulation, installing more efficient heating systems, and reducing air leakage.

Under Section 11/Regulation 23 of the regs renovation such works as this stripping down the element to expose the basic structures and rebuilding would be renovation.

If more than 50% of the thermal element is renovated, then the whole must be replaced meet the improved u-value of a flat roof (0.18)

Or the works fall under major renovation when more than 25% of the surface area of the entire building envelope is renovated.

However, there are limitations to this. If achieving the U-value is either
a. Not technically or functionally feasible
b. Would not achieve payback in 15 years or less.

Question 32

Victoria Estate, Ruislip
(Composite Cladding Panels)

What other building elements can be affected by the type of cladding system used?

Answer 32

Frame
Roof
M&E

Question 33

Victoria Estate, Ruislip
(Composite Cladding Panels)

How is composite metal cladding fixed to a steel frame?

Answer 33

How is composite metal cladding fixed to a steel frame?

Question 34

Victoria Estate, Ruislip
(Composite Cladding Panels)

Describe what a composite panel is?

Answer 34

They are a panel of sandwich construction comprising 2 outer layers of steel or aluminium sheets enclosing an inner core. The core is typically of lightweight material (insulation) which bonded with adhesive. It provides a lightweight yet strong and durable external materials than can span large distances.

Question 35

Victoria Estate, Ruislip
(Composite Cladding Panels)

What is the main concern of composite panels?

Answer 35

The level of fire protection offered.

Question 36

Victoria Estate, Ruislip
(Composite Cladding Panels)

Why are they a concern for insurers?

Answer 36

They usually incur higher insurance premiums due to the risk of structural collapse (when self-supporting) and combustibility in the fire resisting performance of the insulated cores.

Question 37

Victoria Estate, Ruislip
(Composite Cladding Panels)

What are different types of material used for the insulation

Answer 37

Polystyrene (EPS)
Polyurethane (PUR)
Polyisocyanurate (PIR)
Mineral Wool

Question 38

Victoria Estate, Ruislip
(Composite Cladding Panels)

What is LPCB?

Answer 38

The Loss Prevention Certification Panel is an insurance backed set of standards/testing regimes that cover the vast majority of construction products. Simply, if a product is LPCB approved then it is recognised by insurers as low risk, high quality and generally acceptable, attracting lower premiums and in turn driving specification power.

Question 39

Victoria Estate, Ruislip
(Composite Cladding Panels)

Why was LPCB related to the composite panels?

Answer 39

This is The Loss Prevention Certification Board operated by BRE who evaluate the performance of composite panels in fire spread and fire resistance. Generally, EPS and PUR panels are not LPC complaint. A list of approved products and services is issued by the LPCB.

Question 40

Victoria Estate, Ruislip
(Composite Cladding Panels)

What is the issue with Kingspan going forward?

Answer 40

BRE recently ended their relationship with Kingspan and affiliated companies as a clear message to the industry. Meaning the BRE Redbook an online registry of construction products that have passed relevant tests has removed all Kingspan products. But this only applies to products manufactured post June 2023.

This could lead to:
- Increased insurance premiums
- Refusal to insure
- Reduced acquisition appetite

Question 41

Victoria Estate, Ruislip
(Composite Cladding Panels)

What do the Building Regulations say about composite panels?

Answer 41

At the time of my advice the following did not apply, but recent changes now states any ACM panel is banned.