Preservation Treatments (Surrey) Ltd.

Wall Ties and Structural Reinforcing

Most homes built in the last hundred years are of cavity wall construction; the external walls are built of two leaves of brickwork linked with steel ties. This makes for a warmer and drier home. But unless the ties are of stainless steel, or very heavily galvanised mild steel, there is a tendency for the ties to rust making the wall unstable and sometimes causing bowing of the brickwork.

Characteristic signs of corrosion include horizontal cracking of the bed joints in which the ties are laid, caused by expansion of the metal during corrosion. Mild steel ties have a shorter service life than the brickwork in which they are placed and during the life of the building may need replacement with stainless ties.

Where there are signs of structural cracking, instability, failed lintels, ground movement etc, there are several methods of remedial action which may be undertaken to relieve the problem. These actions include using 'Lateral Restraints', 'Anchor Systems' (tying the masonry to the timber frame or floors, or other stable structure), crack stitching and/or mortar bed reinforcement (inserting narrow helix profile steel bars).