Wall Tie Corrosion is getting much worse in Yorkshire’s housing and commercial buildings.
How wall tie corrosion came about.
We started out installing cavity wall ties; to replace rusty ones, back in 1985. Just about the only houses we looked at back then were those built before world war two. Those houses were amongst the first to use cavity walls, which need metal ties to support the outer brick or stone cladding. Metal rusts of course and the manufacturers and builders recognised that, so most mild steel cavity wall ties, used in these pre-war houses were chunky thick fishtails, either zinc galvanised or coated in a black bitumen based paint; ‘black-japan’ was often used.
Houses were built to last then and after forty or so years, when cracks in the mortar beds started to appear in some of these houses, questions were asked. It was discovered that the original metal cavity wall ties were rusting quite badly in many of these pre-war houses and a new remedial wall tie replacement industry sprang into life. Brick-Tie were among the first wave of these new firms, offering identification of wall tie corrosion problems and a wall tie installation and replacement service where this was needed.
Wire ties and the time bomb of ‘hidden’ wall tie corrosion.
That was over 26 years ago and now we are seeing a new breed of wall tie corrosion emerging in Yorkshire’s housing.
Why? – sadly, the issue of poor galvanising carried on, well into the post war years; right up until the early eighties defective cavity wall ties were still being incorporated into new houses… all those timber frame homes erected in the 70’s and ubiquitous ‘wimpy’ homes, which blossomed around Yorkshire and beyond at that time, contained wall ties which were manufactured to a lower standard than was adopted later.
This is not the fault of the builders or the Architects – the standards approved by BRE and British Standards were inadequate, so the quality of the house has nothing to do with the quality of the cavity wall ties – they can be just as rusty in even the highest specification building of this age – domestic, local authority or commercial buildings. In fact the post war period saw an explosion of high-rise buildings too and many of these tower and office blocks have poorly galvanised wall ties installed.
This didn’t matter back in the 1980’s; these houses were brand new and rust was uncommon. Now, a quarter of a century later we are finding houses built in the 50’s, 60’s and 70’s with galvanised wire ties in, which are so rusty that the walls are in danger of collapse. This is of greater concern than wall tie corrosion in those pre-war properties for one very striking reason – wire ties are made from very thin section metal… wire.
Why is wire tie corrosion so important?
What this means is that anyone buying a post war house built before 1983 should have a wall tie survey carried out. A survey will identify any corrosion issues before the problem becomes dangerous or expensive to repair.
Generally, where thin section wire ties are installed the repair is one of installing new stainless steel ties, without the need to remove or structurally isolate the rusting items – they can be left to rust away, with the new Helifix stainless steel wall ties ties taking the strain.
Virtually all catastrophic failures we get called to these days involve post war property with wire ties present. Significant corrosion in pre-war housing, approaching wall tie failure is almost always preceded by horizontal cracking in the outer leaf – something which thankfully serves as a warning in most cases.
Free wall tie surveys are available across Yorkshire via our survey team – call 0800 591541 for further details or use our wall tie survey contact form.