Cavity wall construction has almost entirely replaced the solid wall particularly in low rise domestic homes over the past 80 years and its design ensures that the inner leaf wall will remain relatively dry.
Wall ties are designed to provide mutual support and transfer the applied lateral or vertical loads to the foundations.
Wall ties used from early Victorian construction to pre 1920 were usually made of wrought iron or cast iron and have generally performed much better than their more modern counterparts made of mild steel.
The corrosion of wall ties is due to many influences and walls are constructed to eliminate the elements which give rise to attack and failure of the wall ties.
The first visible signs of the corrosion of the existing metal wall ties which eventually lead to failure show themselves in several ways. There may be fine and continuous cracks in the horizontal bed joints. Bulging or bowing of the outer skin of the cavity may also be visible. There may be cracking above and around window and door openings. Any evidence of bulging, cracking or spalled render should be investigated by a qualified surveyor.
If cavity walls are insulated and a corrosion problem exists, the wall tie inspection may not be possible as the ties will be hidden from view. It is important to inform your surveyor as soon as possible if you know you have cavity wall insulation.
The kind of remedial treatment a wall may require can vary from repointing to complete demolition of the wall and re-build. It is therefore very necessary that a thorough inspection is carried out by a competent surveyor able to diagnose the problem and select the appropriate type of remedial treatment. It is also important to remember that all remedial wall ties rely on the quality of the wall material. The better the material, the better the fix.
We are able to offer a free survey to anyone committed to a housing sale chain. This means that if you are in a sale chain and have had a homebuyers or mortgage valuation survey, we can provide you with a free estimate. Our qualified and experienced surveyors are able to undertake professional surveys independent from a conveyancing chain, letting agent request or home owner enquiry. Find out more!