Wall tie corrosion

[Big_les]

Hi all. In looking at repairing cracks in our walls, a local company offered a free brick tie check, so I said yes. They attempted to inspect two ties on different walls but could only get a view on one due to cavity wall insulation. The one they borescoped is below;

https://imgur.com/a/D1voWqU

It looks like either a 6 or a 7 on the BRE digest 401; a 6 is advised for monitoring, a 7 says replace. The company are saying replace all the ties, and I tend to believe them, but if anyone has any view I'd be grateful.

 

[^woody^]

Does their replacement cost include for a new camera with a better lens?

If the walls are cracked then the ties need replacing.

Otherwise take a brick out and look at one, it will be much clearer

 

[Big_les]

Thanks - we had a structural engineer in as well, and neither his report nor this company's actually linked the cracking to the ties; it was down to the drains in one case and poor conservatory and window installations in all other cases. The (wall tie-centric company that took that image) implied that one crack was partly due to wall ties, but if they are only as corroded as that one, and the structural engineer didn't mention it, I don't see how that's relevant (and it isn't in the report).

I'm now wondering why they didn't remove a brick to check, and thinking I should get another company to do exactly that.

[edit - the property is 64 years old and the ties are original, so that's another factor. My choices are basically go ahead and get them replaced, the cracks stitched and the whole thing repointed, or to kick the can down the road by getting the cracks filled/repointed.]

 

[Paulg31]

Before spending money replacing wall ties I'd recommend locally opening up the wall for inspection if you're concerned about wall tie corrosion and can't get a clear picture of what's going on from the outside.

 

[dontbelieveawordofit]

wall tie cracks run horizontally at approx 400mm intervals.
any pics?
at circa 1954 they’re almost certainly steel ties not galv.

 

[^woody^]

Wall cracking appearance tends to say what caused it, and the cracks from expanding ties are totally different to any other cause and can't be mistaken for anything else.

A free brick tie check by a company that replaces ties would raise eyebrows, and possibly raise a boot to kick the bloke into the middle of next week.

 

[Big_les]

Thanks guys, I very much appreciate the replies. All of the cracks are vertical hairline or stepped c3mm wide - there's really no evidence of horizontal cracking suggestive of failure.

I suppose the crux of it is - is there any sense in a pre-emptive replacement, given that I need the various cracks stitching (including helibars above the dodgy windows) as well as a fair amount of repointing done. If I'm going to be replacing the ties in the next few years I'd rather do the lot in a one-er and save on scaffolding and (assuming this lot aren't talking *******s) labour, as they will do the ties and the stitching.

Based on what you're saying though, these ties could last another decade or so, and (without a second opinion based on more than one borescope photo) I don't have enough evidence to justify spending a load of money on replacing all the ties.

edit - oh, and Woody, I did have the same gut feeling to be quite honest. I'm always suspicious of companies introducing totally new problems that you didn't invite them to look at. It was just the view of that corroded tie that had me mostly convinced. But I am strictly a layman.

 

[^woody^]

It's possible for ties to have some minor surface rusting and not develop into a problem.

What do the other neighbouring houses look like?

I don't think a pre emptive replacement has any value, unless there is evidence of an actual problem locally.

 

[Big_les]

Thanks, that makes a lot of sense. There's no issue locally that I can see, no horizontal cracking anywhere. I suppose if they're not outright touting for business, it's at least a case of the old 'when you're a hammer, everything looks like a nail' thing.

 

[wessex101]

The image is unclear but probably the fundamental information you need is what pattern of wall tie are they? Could be early wire butterfly ties in which case there is unlikely to be any cracking to the external leaf.