Construction Technology & Environmental Services

Question 1

What is substructure?

Answer 1

All elements of the work that are undertaken below the damp proof course that provides the basis for the superstructure to be constructed upon - e.g. foundations, piers, abutments

It carries the weight of the building to the ground or bedrock

Includes floor insulation, sealing and reinforcement

Question 2

What is the external envelope?

Answer 2

The materials and components that form the external shell or enclosure of a building

These may be load or non-load bearing

Question 3

What are the building regulations?

Answer 3

Statutory instruments that set out the minimum performance standards for the design and construction of buildings

Supported by the Approved Documents and other codes of practice

Question 4

What are the approved documents?

Answer 4

A. Structure
B. Fire Safety
C. Site preparation and damp proofing
D. Toxic substances
E. Sound proofing
F. Ventilation
G. Hygiene
H. Drainage and waste disposal
I. Not in use
J. Heating appliances
K. Protection from falling, collision and impact
L. Conservation of fuel and power
M. Disabled access and facilities
N. Glazing
O. Not in use
P. Electrical safety

Question 5

What are British Standards?

Answer 5

Publications issued by the British Standards Institution prefixed BS

They give recommended minimum standards for materials, components, design and construction practices

Question 6

What are international standards?

Answer 6

Publications issued yesterday the International Organisation for Standardisation - prefixed ISO

They are compatible and compliment the BS

Question 7

What is superstructure?

Answer 7

All internal and external works items above the damp proof course - give the building shape

Made up of:
- External walls
- Stairs
- Roof
- Structural walls
- Suspended Ceilings
- Raised floors

Question 8

What is the function of substructure?

Answer 8

‘Transfer the load of the building to the ground and to isolate it horizontally from the ground’

Question 9

According to the BCIS what does substructure include?

Answer 9

Foundations up to and including the damp proof course

Lowest floor assembly below the underside of the screed, or the lowest floor finish

Basement excavation

Basement retaining walls up to and including the damp proof course

Question 10

What are the different categories of foundations?

Answer 10

Shallow foundations - used where the load imposed by the structure are low relative to the bearing capacity of the surface soils (e.g. trench fill, raft, rubble trench)

Deep foundations - needed where the bearing capacity of the surface soils is not adequate to support the loads imposed by a structure and so those loads need to be transferred to deeper layers with higher bearing capacity

Question 11

Types of shallow foundations:

Answer 11

Strip foundations

Trench fill - form of strip where excavation is filled almost entirely with concrete

Rubble trench - use loose stone and rubble to minimise use of concrete and improve drainage

Pad foundations - rectangular or circular pads support localised loads e.g. columns

Raft foundations - slabs that cover a wide area, often the entire footprint of a building (can include beans or thickened areas to provide additional support)

Question 12

Types of deep foundations

Answer 12

Pile foundations - made of long slender columns of steel or reinforced concrete

Pile walls - placing piles directly adjacent to one another to create a temp or permanent retaining wall

Diaphragm walls - excavating a deep trench filled with engineering slurry

Compensated foundations

Ground anchors - transfer high loads using a grounded anchor to mechanically transfer loads to the ground

Question 13

Types of superstructure:

Answer 13

Frame - main floor, roof beams, trusses,

Upper floors - suspended floors, balconies, walkways

Roof - structure, coverings, drainage and features

Stairs and ramps - connecting floors

External walls - enclosing walls , but does not include walls to basements designed as retaining walls (these are substructure)

Windows & ext. doors - openings in external walls

Internal walls - partitions, cubicles, dividers

Doors - internal openings in walls and partitions

Question 14

What are piles?

Answer 14

A series of columns constructed or inserted into the ground to transfer the load of a structure to a lower level of subsoil

They are used where no suitable foundations conditions are present at near ground level, or if there is a high water table

Question 15

What are the different types of piles?

Answer 15

Sheet piles
- deep trench is excavated and concrete poured in situ
- can be used to form basement walls or retaining walls

Secant piles
- interlocking piles, are bored to provide a combination of foundations and basement walls
- they support in providing a waterproof structure and are often seen when a top-down construction method is used

Bored piles
- an auger is used to excavate the soil and then concrete is poured in once complete

Pre-cast piles
- piles are hammered into the ground
- not often favoured due to the high noise levels and lack of flexibility in terms of depth required

Question 16

What are the problems for a PQS regarding cost control with piling and who owns the risk?

Answer 16

The end depth of the piles are never certain and the procurement route determines who takes the risk

E.g. under traditional or D&B the main contractor would usually take risk ownership whereas under management contracting the risk would remain with the employer

Question 17

What are the main types of excavation for forming basements?

Answer 17

Open Excavations - used battered excavation sides which are cut back to a safe angle, eliminates the need for temp earth works support and can be used to construct basement walls (requires additional excavation costs and significant working space)

Perimeter Trench Excavation - used to form basement walls - then inside of basement is removed once walls are complete

Complete Excavation - used in firm subsoils, the centre of the basement is excavated first then the basement slab cast whilst the sides are supported by stunts

Question 18

What are the technical advantages of steel frames?

Answer 18

Often quicker to assemble in comparison to alternative methods

100% recyclable and inorganic - meaning they wont warp, split, crack or creep

Offer the highest weight to strength ratio of any building material

Dimensionally stable and do not expand or contract with moisture or temp changes

Due to strict manufacturing controls, consistent materials quality can be achieved

Steel is non-combustible so it will not contribute to the spread of a fire

Steel frames are lighter in comparison to concrete frames and will benefit from a cheaper foundation solution

Question 19

What are the technical disadvantages of steel frames?

Answer 19

Require fire protection to be retrospectively installed

Fixing components may require replacement over time

The price of steel often fluctuates and so results in a lack of cost certainty

Installation of steel frames requires experienced builders at an additional cost

Resources can also be difficult to acquire depending on market conditions

Question 20

Technical advantages of concrete frames?

Answer 20

Fire protection is often provided inherently as part of the structure

Due to offering a slower form of construction in comparison to alternative methods, this will likely result in reduced cash flow expenditure early in the project

Maintenance requirements associated with concrete frames are relatively low in comparison to alternative methods

Concrete frames often provide good sound and heat insulation properties in comparison to steel frames

Question 21

What is the definition of a basement?

Answer 21

A storey with a floor which at some point is more than 1,200 mm below the highest level of ground adjacent to the outside walls.