Wall Tie Corrosion
Cavity walls incorporating metal wall ties have been constructed in this country since the end of the 19th Century. Unfortunately many of the ties installed are considered sub-standard by today's British Standard and all ties manufactured prior to 1981 (when the standard was improved) could be subject to premature corrosion.
Modern materials and an improved B.S reduce the problem considerably.
When metal ties corrode they expand to many times thicker than their original size. This expansion occurs mostly in the mortar joints of the external skin wall.
As the joints crack open and expand the outer skin wall grows in height and breaks away from other walls which causes stepped cracking. Excessive cracking can weaken the walls and they become unstable.
The system consists of installing new stainless steel remedial wall ties through the centre of the inner and outer skin walls at staggered centres to the existing wall ties.
The above ties are made from high quality stainless steel and manufactured to British Standards. The original wall ties are either removed or isolated in the Mortar bed.
All holes drilled and areas where mortar has been removed are filled with coloured mortar to match as closely as possible the existing bricks or mortar joints respectively.
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