What is cavity wall tie corrosion and how can you identify if you need them replaced?
Cavity wall tie corrosion is the term used when the cavity wall ties bedded in a property with a cavity wall construction corrode due to the breakdown of their protective coating.
Wall tie corrosion can seriously damage external walls and could, in some cases, make a building unstable.
THE PROBLEM
The increasing incidence of wall-tie failure due to corrosion is now causing very serious concerns in many parts of the United Kingdom. The problem has arisen because the zinc coating applied to the mild steel ties used extensively to link cavity wall constructions was insufficient to prevent corrosion.
Up to 1981, when the British Standard was amended to specify thicker coatings of zinc, the anticipated life of galvanised ties was only 15-20 years. It is now estimated that the ties used in over 7 million buildings will have exceeded their minimum life expectancy.
Cavity wall ties are usually made of mild steel and inserted in the cavity space linking the external wall of a property to its internal wall.
Older wall ties are of a flat ‘fishtail’ design, whilst more modern ties are twisted wire butterfly pattern. As cavity wall ties are expected to be exposed to water they are galvanised to resist corrosion. Over time, the galvanising can break down leading to wall tie failure.
There are a number of signs to help determine if your property is affected:
1. Vertical and horizontal cracking
2. Sagging of lintels
3. Upward cambering of window sills
4. Lifting of roof edges
5. Separation of window reveals
6. Separation of floors
7. Bulging brickwork
Our surveyors will carry out a thorough inspection to establish the need for remedial work.
The surveyor will:
1. Complete a thorough examination of your property, inspecting random wall ties with an endoscope.
2. Identify cracks and damage to brickwork.
3. Provide you with the most effective treatment for wall tie failure.
Our specialist technicians have the expertise necessary to effectively treat the problem of wall tie failure. Treatment will include:
1. Drilling holes in brickwork for access to wall ties (using the appropriate access equipment where needed).
2. Installation of new stainless steel wall ties.
3. Isolation of existing wall ties to prevent further damage.
4. Preserving the appearance of your property – make drilled holes good to match the existing wall appearance.
J&J Crump & Son Ltd work is covered by a 25-year guarantee, which can be passed on to future owners of the property.