Front Cover of Volume 5
Volume 5
by R Greenhalgh (Ed)
Published by Pitman & Sons Ltd
11th December 1926
No ISBN number
Cavity Walls
In bleak and exposed situations, subject to driving rain and snow, the external walls of buildings are frequently built with a space in their thickness, usually 2" wide, to prevent penetration of dampness into the interior of the building
Near the sea, the spray carried by the wind, deposits salt on the face of the walls, and this permanently attracts moisture from a humid atmosphere
A cavity ensures a more uniform temperature
inside the building, and protects from decay any woodwork in contact with the wall
In constructing hollow walls, the outside portion should only be considered as a protecting skin, and not as any part of a load-bearing structure
The inside wall should be of sufficient thickness to carry the weight of floors and roof
The outer wall actually receives support from the inner, by the bond ties which are built in as the work proceeds
These may be specially made vitrified bricks,
cast-iron, wrought-iron,
or wire-shaped ties and placed in rows about 18" apart vertically, and about 3 ft. apart horizontally
Each row is set centrally between the row below
The cavity must be well ventilated by inserting sufficient air-bricks
Provision must also be made for drainage of any accumulated condensed moisture, by leaving small
weep-holes at the bottom of the cavity just above the damp-proof course
All floors should be ventilated direct from the atmosphere and not from the cavity. The usual method is to build in short lengths of pipe through the thickness of the walls, and sloping towards the outer face so as to convey no moisture to the inner wall
The cavity must be closed at the top to prevent access of vermin. and to ensure uniformity of temperature
Mortar dropping onto the wall-ties can become saturated with moisture and cause damp patches. To prevent this, lay battens bound with hay along the wall-ties as the work proceeds. These battens catch falling mortar, and are drawn up when the wall reaches the height of another row of ties
In bleak and exposed situations, subject to driving rain and snow, the external walls of buildings are frequently built with a space in their thickness, usually 2" wide, to prevent penetration of dampness into the interior of the building
Near the sea, the spray carried by the wind, deposits salt on the face of the walls, and this permanently attracts moisture from a humid atmosphere
A cavity ensures a more uniform temperature
inside the building, and protects from decay any woodwork in contact with the wall
Cavity Walls
Fig. 32 - Volume 5 Page 216
Fig. 32 - Volume 5 Page 216
The inside wall should be of sufficient thickness to carry the weight of floors and roof
The outer wall actually receives support from the inner, by the bond ties which are built in as the work proceeds
These may be specially made vitrified bricks,
cast-iron, wrought-iron,
or wire-shaped ties and placed in rows about 18" apart vertically, and about 3 ft. apart horizontally
Each row is set centrally between the row below
The cavity must be well ventilated by inserting sufficient air-bricks
Provision must also be made for drainage of any accumulated condensed moisture, by leaving small
weep-holes at the bottom of the cavity just above the damp-proof course
All floors should be ventilated direct from the atmosphere and not from the cavity. The usual method is to build in short lengths of pipe through the thickness of the walls, and sloping towards the outer face so as to convey no moisture to the inner wall
The cavity must be closed at the top to prevent access of vermin. and to ensure uniformity of temperature
Mortar dropping onto the wall-ties can become saturated with moisture and cause damp patches. To prevent this, lay battens bound with hay along the wall-ties as the work proceeds. These battens catch falling mortar, and are drawn up when the wall reaches the height of another row of ties
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