Hi there - hope this is the right section to post this in! We are looking to buy a 1950's 3 bed semi which has rendering on the outside. However, the Home Buyers survey said there was horizontal cracking on the outer rendering so we should get a wall tie survey. We found a company who did the survey and said they drilled three holes (front, side, back) and inspected some wall ties which were corroding (although seems not a lot?) Here's the image he sent back with a quote for £6000 to replace the wall ties. I am unsure if this is high or not. Should we get this doen immediately?
Sounds like unnecessary and expensive work to me. Minor surface rust is to be expected after 70 years, it certainly doesn't look serious enough to cause a structural issue.
I would expect to see broken wall ties if that was the cause of the cracking. From the photo alone I do not think that wall tie corrosion is an issue. Get a better inspection done or walk away.
Wall tie corrosion is a real problem especially in some parts of the country. The tie in your picture is absolutely fine though. Did they do the simple thing of putting a straight edge up the wall to see if there was a bow?
There's 2 main types of wall tie that cause failure. 1 the thinner butterfly ones. These tend to snap when rusted and aren't normally thick enough to lift the bed joints. First signs of failure are usually bowing of the walls. 2 twist or fish tail ones. Much thicker and usually expand enough when rusted to lift the joints. First signs are usually horizontal cracks in the wall. Rendered walls tend to show the cracks earlier. Usually take much longer to snap than the butterflies. Twist types cost more to replace normally, because the butterflies can be left in the wall, whereas the twists have either to be removed, or as is common now isolated. The tie in the photo is probably rusted only at the bit in the external bed joint at the moment. This is where it often starts and where the damage is done. Twist ties where the worst type for building with. You couldn't bend them to match the inner skin, or keep them out of the way, and you had to be careful as you straightened up when laying the lower courses.
Unfortunately we were not there to see what he did for the report. But the tie looking so clean (apart from the tiny bit of rust) was a red flag which is why I got on here
Yes, this is what prompted me to get on here and ask your opinion. I have no idea what a corroded tie would look like but it looked OK to me
If the ties have rusted enough to lift the joint a bit, the problem is that more moisture can get into that joint now and cause the ties to deteriorate more. It's always worth getting more estimates.
Someone suggested that fixing the cracks in the rendering might prevent further corrosion as it would prevent moisture getting to the ties. Is this not an appropriate solution?
Blown wall ties generally are spaced horizontally circa 18" apart which is a good indicator. The wall can get a crack the full width and be lifted by the rust alone. Yours don't look worryingly bad as 1950s build ties were heavily galvanised.
Thanks. So do you think the crack in the first pic is likely just the rendering is old and knackered?
The only way to be sure is to open up the crack carefully and see if the bed joint on the masonry has opened up. You have to be aware that companies that do free surveys are more likely to find work for themselves. You could use the estimate to negotiate a different offer, although it is still a sellers' market.