Wall Ties

DD140: Part 2: 1987 Recommendation For The Design Of Wall Ties

This document provides recommendations for the design of wall ties for masonry and timber construction in the UK. There are 6 different categories of wall ties, which are determined by strength, function and use. Types 1 to 4 are for masonry to masonry ties, and types 5 and 6 are for use in timber frame construction.

BS5628: The Use Of Masonry: Part 1: 2005

This gives details on the embedment, length of tie, density and positioning of the wall ties. By conforming with DD140, the ties will meet these requirements.

BS EN 845-1: 2003 Specification For Ancillary Components For Masonry – Part 1: Ties, Hangers And Brackets

Where wall ties are connecting to beams, columns or other parts of a building, the European Specification denotes the requirements of material, tolerance and tie type. The standard BS EN 845-1 also applies for interconnecting masonry.

Positioning & Density Of Wall Ties

Wall ties should be placed evenly over the area of the wall except for openings, where ties should be staggered. At vertical edges of an opening, unreturned or unbonded edges, and also at vertical expansion joints, additional ties should be placed at a rate of one per 300mm in height and located not more than 225mm from the edge.

Spacing Of Ties

Wall ties should be built into each leaf with a minimum embedment of 50mm. However, ACS recommend an embedment of 62.5mm to allow for site tolerances. Drip features on a wall tie should be placed at the centre of an open cavity.

The bending of installed wall ties should be forbidden at all times as this affects the performance of the tie and weakens the embedment in the inner leaf.