Deck 13: Flat Roof Construction and Coverings

Question 1

One major advantage of using mastic asphalt as a covering on flat roofs is

A) It can be applied hot
B) It is lighter in weight than bituminous felt
C) It has a similar coefficient of thermal movement to the roof structure
D) It has a similar coefficient of moisture movement to the roof structure
E) It is jointless

Answer 1

E

Question 2

The first layer of bituminous felt covering is partially bonded to the roof structure to allow

A) Differential movement to occur between the roof and the covering
B) The insulation to breathe
C) Water vapour to diffuse through the covering
D) Wind forces to disperse through the covering
E) Sound waves to be transmitted through the roof

Answer 2

A

Question 3

Sheet metal coverings are rarely used on domestic flat roofs because

A) They attract birds
B) They are more expensive than other coverings
C) They are less durable than other coverings
D) They cannot be laid on suspended timber flat roofs
E) They need a screed to be laid over them

Answer 3

B

Question 4

Cold deck design has the benefit of allowing a flat roof to

A) Warm up quickly
B) Warm up slowly
C) Cool down quickly
D) Cool down slowly
E) Use cork insulation

Question 5

The vapour barrier in a warm deck roof design needs to be located

A) Below the deck
B) Above the insulation
C) Below the insulation
D) Within the insulation
E) Above the covering

Question 6

The thermal insulation in an inverted roof design needs to be

A) Vapour permeable
B) Water permeable
C) Fixed to the decking
D) Soundproof
E) Weighted down

Question 7

Interstitial condensation in a flat roof can cause the insulation to

A) Expand
B) Contract
C) Become more efficient
D) Become less efficient
E) Improve in appearance

Question 8

White spar chippings are often placed on the top of flat roofs to

A) Reflect the solar radiation
B) Absorb the solar radiation
C) Protect the covering from being punctured when walked upon
D) Slow down the drainage of water from the roof
E) Stop the roof from being blown off by the wind

Question 9

Single ply sheeting systems have become popular because they

A) Are cheaper than built up felt coverings
B) Do not require insulation to the roof
C) Have good resistance to weathering
D) Can be laid to very shallow gradients
E) Do not need to be overlapped at joints

Question 10

Sheet lead is a more sustainable flat roof covering than bituminous felt because

A) It has greater thermal movement
B) It does not require an isolating membrane
C) It is extracted from natural ores
D) It has a longer life span
E) It is biodegradable and non-toxic to the environment

Question 11

Thermal insulation is important in roof construction because

A) The roof structure needs to allow heat to escape
B) The roof structure needs to allow water vapour to condense
C) Roof structures are naturally good thermal insulators
D) Hot air rises
E) Thermal insulation improves the fire resistance of roofs

Question 12

Flat roofs have become less popular than pitched roofs because

A) They have a shorter life span
B) They are difficult to gain access to
C) They are more expensive
D) They take longer to construct
E) They lose more heat

Question 13

The recommended minimum gradient for a flat roof should be

A) 1 in 30
B) 1 in 40
C) 1 in 50
D) 1 in 60
E) 1 in 70

Question 14

The fall to a suspended timber flat roof is created by

A) Tapering the top of the joists
B) Tapering the bottom of the joists
C) Tapering the firrings
D) Tapering the insulation
E) Tapering the decking

Question 15

The main reason for joists overhanging the external wall at the eaves is to

A) Shelter the wall beneath
B) Extend the span of the roof
C) Provide a fixing for the gutter
D) Lower the gradient of the roof
E) Provide a fixing for the fascia board

Question 16

Flat roofs and roofs of low pitch are subjected to high wind forces causing

A) Compression
B) Twisting
C) Suction
D) Sliding
E) Shearing

Question 17

The soffit board to a flat roof is used to

A) Provide a fixing for the fascia board
B) Provide a fixing for the decking
C) Provide a fixing for the gutter
D) Provide a fixing for the kerb
E) Cover the gap between the fascia board and the wall

Question 18

Reinforcement is placed in suspended concrete roof slabs to prevent cracking due to

A) Compression under load
B) Deflection under load
C) Sliding under load
D) Shearing under load
E) Twisting under load

Question 19

Propping is provided to formwork for suspended concrete roof slabs to

A) Provide support to the reinforcement
B) Provide a platform for the workmen placing the concrete
C) Provide support to the insulation
D) Provide support to the concrete during setting
E) Provide support for the electrical services

Question 20

Lightweight aggregate is used in the screed on suspended concrete roof slabs to

A) Increase the thermal conductance of the roof
B) Reduce the porosity of the roof
C) Increase the strength of the roof
D) Reduce the weight of the roof
E) Reduce the span of the roof