Tie Length & Density
Wall ties should be of the correct length to ensure they are properly embedded in the masonry. We recommend tie lengths which achieve an embedment of between 62.5mm and 75mm.
For typical layout of wall ties indicating maximum spacing, see the image below or click the link.
Typical layout of wall ties indicating maximum spacing (GIF, 215 KB)
Recommended Lengths of Masonry/Masonry Wall Ties
|Cavity Width (mm)||Length of Wall Tie (mm)|
Notes: For Two-Part Tie click here. The Ancon Staifix-Thor Helical TJ2 wall tie requires 85mm embedment in the inner leaf of blockwork and 70mm in the outer leaf of brickwork.
Density & Positioning of Ties
For walls in which both leaves are 90mm or thicker, ties should be used at not less than 2.5 per square metre (900mm horizontal x 450mm vertical centres). This spacing may be varied when required by the Building Regulations. Ties should be evenly distributed over the wall area, except around openings, and should preferably be staggered.
At vertical edges of an opening, unreturned or unbonded edges, and vertical expansion joints, additional ties should be used at a rate of one per 300mm height, located not more than 225mm from the edge.
Timber Frame Ties
Timber frame ties should be installed at a density of 4.4 ties per square metre in buildings where the basic wind speed does not exceed 25m/s (BS 6399-2: 1997 Code of Practice for Wind Loads). The density should be increased to 7 ties per square metre in more severe situations.
Remedial Wall Ties
No British Standard has yet been defined for the spacing of remedial wall ties. However, accepted practice is to follow PD 6697 that is 900mm horizontally and 450mm vertically in a staggered pattern with 300mm vertical centres around openings within 225mm of the opening.
Designed to minimise thermal bridging in masonry cavity walls, the patented Ancon Thermal Windpost (TWP2) from Leviat offers up to an impressive 70% reduction in thermal transmission through the span of the windpost.
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