Deck 22: External Wall Finishes

Question 1

One disadvantage of using a strong cement:sand mix for rendering is

A) It is likely to dry too quickly
B) It can be difficult to bond to blockwork
C) It can crack during drying
D) It is unlikely to be frost resistant
E) It is difficult to achieve a textured finish

Answer 1

C

Question 2

Dry backgrounds need wetting prior to the application of rendering to

A) Prevent uneven weathering
B) Reduce suction
C) Improve frost resistance
D) Reduce rain penetration
E) Allow a weak mix to be used for the undercoat

Answer 2

B

Question 3

The bond between the undercoat and finish coat of a render is provided by

A) A spatter dash coat
B) Expanded metal lathing
C) A pebble dash coat
D) Fluting
E) Scratching

Answer 3

E

Question 4

Smooth rendered finishes can craze because

A) A steel trowel is used
B) Too little water is used in the mix
C) The sand contains impurities
D) The finish is overworked
E) The finish is subjected to frost before it has set

Question 5

One advantage of a rough cast finish is that

A) It reduces rain staining
B) It is applied by a machine
C) A low plasticity mix can be used
D) It has higher durability than a textured finish
E) It has a lower density than a smooth finish

Question 6

To prevent ground moisture from entering the wall above the DPC via the render

A) The render should contain waterproof cement
B) The render is finished above the DPC
C) The DPC is set back from the face of the render
D) The DPC should be made from sheet metal
E) A bituminous paint coating should back the render

Question 7

Tile hanging is not normally used on ground storeys because

A) It would cover the DPC
B) The abutment with a door frame is vulnerable to water penetration
C) It needs to be sheltered at its head by an overhanging roof
D) It is vulnerable to damage
E) Counter battening would need to be used

Question 8

Counter battens may be used for tile hanging in order

A) Provide ventilation to the cavity between the tiles and the wall
B) Enable thermal insulation to be attached to the wall behind the tiles
C) Enable a breather membrane to be attached to the wall behind the tiles
D) Enable a vapour control layer to be attached to the wall behind the tiles
E) Provide a fixing for a lead lashing at the head and foot of the tiles

Question 9

Secret nailing of weatherboarding to timber battens is used mainly because

A) It prevents the boards being removed by vandals
B) It improves the appearance of the weatherboarding
C) It reduces stresses in the timber caused by thermal movement
D) It prevents the fixings from working loose due to moisture movement
E) It protects the fixings from corrosion

Question 10

Western Red Cedar is often specified for weatherboarding because it

A) Derives from sustainable forests
B) Can be treated with non-toxic preservatives
C) Is very durable
D) Does not contain lignin
E) Does not require to be fixed to timber grounds