Repairing lime-based stucco, damp terrace
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Repairing lime-based stucco, damp terrace

by niftyprose » Sat Jan 08, 2022 4:15 pm

Hello guys, this is a very specific issue. I'm hoping someone else has dealt with the same thing. (I posted this topic on another forum, in case anyone's got deja vu.)

My partner bought her terraced house in Lancs a few years ago. It's a Victorian two-up two-down in generally good nick but with some damp issues.

We renovated ourselves and hired a builder to use a tanking compound all over the downstairs. This improved things, but we still got damp patches on the front wall, especially in winter. The front wall is stucco, probably lime-based, applied straight onto masonry.

Last spring I went up on a tower and tapped all over the wall to find the worst patches of stucco, then took them off with a chisel. The masonry behind showed water damage. I think water had gathered behind the bad stucco and then found its way through the wall. I used an expanding repair mortar to fix the masonry, then used Touprelith to patch the stucco.

This was 'close but no cigar' -- it fixed the worst damp patches, but there are others, some of which don't align with bad patches of stucco (I'm guessing that water is travelling down inside the wall from damage points higher up).

Obviously I could take off all the stucco from the front, eyeball the damaged masonry, squeeze in some Fischer expanding mortar, and then apply fresh stucco over the top. I'll do it if there's no alternative, but it's a lot of work and I don't want to annoy the neighbours by cracking their stucco.

* Is there some neat way to spot the areas of stucco which are causing the problems, or should I just keep tapping and listening for hollow sounds?
* Can anyone recommend a stucco patch? Touprelith works well but I think it would be smarter to use something lime-based to match the old stuff.


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