All experienced builders know that good quality, reliable wall ties are vital in holding the walls of a cavity wall structure together. The ends of the tie lock into the cement and also help prevent water transfer from the outer to the inner leafs.
Poor galvanisation
Unfortunately, cavity wall ties made from galvanised steel can often fail and cause huge issues for homeowners. If the galvanising isn’t done correctly then water can penetrate the outer leaf of the wall and cause the tie to rust, causing even more damage. As the tie rusts, it will swell and cause cracks to appear in the wall. All in all, dodgy wall ties are a huge problem and need to be dealt with swiftly and effectively to prevent large scale structural issues arising.
NB: If you’re already faced with a cracked or cracking wall you should proceed with caution. If a wall has noticeable cracks running horizontally at 4-8 course intervals, it’s likely that you are dealing with corrosion. If so, these swollen ties will be causing a lot of distress to the wall, weakening it significantly. If in doubt, get in touch with a qualified engineer to find out whether additional stabilising works are needed.
Defective wall construction
Other issues that could mean your wall ties need to be replaced include wall problems defective wall construction. If the ties have been incorrectly fitted (e.g. they’re too short for the wall or they’ve been fitted at incorrect points or spacings) then cracks and related problems can arise.
So, how do we replace the ties?
Let’s be honest: it’s not easy to replace wall ties. After all, walls are a fairly vital part of any building and they need to be treated very carefully. But the good news is that it’s entirely possible when we follow the right steps. The first- and most important- step before any work starts is to ensure that the outer façade of the wall is firmly attached to the building’s inner wall, allowing loads to be carefully shared. This is crucial: after all, you don’t want to bring the roof down!
What type of wall tie to use?
Good question. It’s not tricky to find out, but you will need to check a few things. The first step is to see whether you have cavity wall insulation. If you do, make sure you steer clear of chemically reactive resins and only use a wall tie system that has the smallest installation bore. This means you won’t sacrifice any of the crucial thermal efficiency.
The second part of your investigation involves drilling at least one investigation hole per elevation to see whether your wall is solid or if they have any perforations. If it’s solid, you’ll need a mechanical tie, helical screw in tie or a resin grouted tie. For perforated walls, you’ll want a resin grouted tie in a sleeve or a helical screw tie. If it’s insulated, you should use a mechanical tie or a hammer fix screw in tie. Finally, for buildings that need a greater than half hour fire performance use a helical screw in wall tie.