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What is cavity wall tie corrosion?

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.

What are cavity wall ties?

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.

How to identify cavity 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

One of 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 the most effective treatment for wall tie failure.

Replacements for cavity wall ties

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.

JJ Crump is a trading name of J & J Crump & Son Ltd. Our registered office can be found at 1a Nethermoor Lane, Sheffield, S21 1BZ. We are registered in England No. 4153056 and are authorised and regulated by the Financial Conduct Authority. We are a credit broker and not a lender. We offer credit facilities from one lender.