Cavity walls have been used in Sydney since the late 1920s. Two masonry leaves are joined together by metal wall-ties to create external walls. Cavity walls have been the most common form of house construction since 1950.
Also, wall-ties made in stainless steel have been used since the 1980s, although early forms did not have this feature and were more susceptible to corrosion and expansion when exposed to moisture. Even now to handle these issues, you need the services of wall tie substitute in Sydney.
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This can cause brick fractures and other defects, such as:
- Bowing of brickwork
- Cracks in mortar-pointing by diagonal cracks
- Horizontal cracks in mortar beds.
How can you tell if a cavity wall is present?
You can see the "bond" or pattern of the bricks. The wall will be considered a cavity wall if all bricks are laid with their long edges facing you ('stretchers) It's likely to be a solid wall if bricks are applied with their short edges ('header) facing you.
A cavity wall, which is usually rendered, measures approximately 10 1/2 to 11 inches. A solid wall measures 9 to 13 1/2 inches depending on how many bricks are used.
Butterfly wire ties are lightweight and can cause little to no external signs. Without external evidence, the link can corrode through.
However, fishtail and upright twist ties with their larger bulk of metal can expand enough to cause visible splitting in the mortar bed where they are attached.