Deck 8: External Walls

Question 1

The weather resistance of an external wall can be improved by

A) Reducing the thickness of the wall
B) Using permeable materials in the wall
C) Applying a plaster finish to the internal surface of the wall
D) Installing insulation to the external surface of the wall
E) Incorporating a cavity in the wall

Answer 1

E

Question 2

The fire resistance of an external wall can be improved by using materials

A) That have been through the refractory process
B) That have not been through the refractory process
C) That have a high moisture content
D) That have a low moisture content
E) That have a high thermal conductivity

Answer 2

A

Question 3

The slenderness ratio for a cavity wall with 102mm thick external brickwork, 75mm cavity, 50mm partial cavity fill, 125mm thick internal concrete blockwork and 12.5mm plaster finish and having an effective height of 2.4m is

A) 7.95
B) 10.57
C) 11.45
D) 11.92
E) 15.86

Answer 3

E

Question 4

Sulphate attack in external walls causes

A) The bricks to expand
B) The bricks to contract
C) The mortar to expand
D) The mortar to contract
E) The wall ties to expand

Question 5

One disadvantage to internally applied thermal insulation to external walls is

A) It cannot incorporate a vapour barrier
B) It reduces the size of the room
C) It can reduce the fire resistance of the wall
D) It can reduce the compressive strength of the wall
E) It can increase the slenderness ratio of the wall

Question 6

The best way of improving the resistance of external walls to airborne sound transmission is to

A) Separate the external and internal parts of the wall
B) Increase the porosity of the wall
C) Use galvanised strip wall ties
D) Use polystyrene bead insulation in the cavity
E) Increase the density of the wall

Question 7

The external appearance of external walls can be influenced by

A) The texture of the cavity insulation
B) The thickness of the plaster finish
C) The density of the concrete blocks
D) The compressive strength of the render finish
E) The type of mortar joint

Question 8

Efflorescence in external walls is caused by

A) The cement in the mortar
B) Acid rain
C) Soluble salts in the bricks
D) Corrosion of the wall ties
E) A chemical reaction between the bricks and the insulation

Question 9

The greatest eccentricity in an external wall occurs when

A) The joist bears onto the inner leaf of a cavity wall
B) The joist bears onto a joist hanger in a cavity wall
C) The joist bears onto the centre of a solid wall
D) The joist bears onto the inner quarter of a solid wall
E) The joist bears onto the outer quarter of a solid wall

Question 10

Polyethylene is a popular choice for a damp proof course because

A) It is semi-rigid
B) It is moisture impermeable but vapour permeable
C) It extrudes under load
D) It is easy to install
E) It does not need to be lapped at joints