We were instructed to investigate suspected wall tie corrosion at Selbourne, a semi-detached property in Cannongate Road, Hythe. The property is approximately 90 years old, with rendered cavity brick and block walls to the original side and rear elevations.
Horizontal cracking was visible through the render, particularly at higher level. A wall tie detector confirmed that the cracking followed the positions of the original ties. Although dense cavity insulation partially restricted the inspection, accessible ties showed heavy surface corrosion. When assessed against BRE Digest 401, replacement of the affected wall ties was recommended.
After the existing render had been removed and full scaffold access provided by others, we installed new stainless steel neoprene-sleeved wall ties to the original side and rear elevations. The new ties were fitted at 2.5 ties per square metre in accordance with BRE Digest 401, with closer spacing around door and window openings.
The original corroding ties were then located and isolated within the outer leaf to prevent further expansion damage. Installation holes and disturbed mortar were made good , leaving the walls ready for the follow-on rendering work by others.
