Cracks inside house

[Banana770]

Last year we noticed some cracks in our house, mostly on the extension (done about 15 years ago before we lived here). There was quite a big one going down the outside where the extension and house joined, and some internal ones like the pictures. I had a total panic about subsidence, we had a local builder out (with really good local reputation, my family has used him loads too) who told us it was due to needing something fitting to cope with the expansion, which made sense as it’s a south facing wall that’s very exposed to sun. He said to just polyfiller in the cracks inside.

Anyway. The outside is fine, the expansion thing and rerendering seems to have worked, but the cracks inside are back this summer, I think one has actually got the tiniest bit bigger too. Pictures attached (one looks much worse than it is as I repainted round it with the wrong colour!).

Should we just redo the polyfiller or does this need a second opinion? Has anyone had anything like this?

Houses expand and contract constantly with the temperature and humidity. There's not much to do, although you can scrape out the crack well and fill with something more flexible than poly filler and that would help. If it gets worse not better throughout 12 months then worry.

As there are no cracks outside I don’t think you need to overly worry. The joint between an extension and the original should be capable of absorbing movement but inside plaster isn’t. The external work has coped but the dry summer has caused shrinkage inside. All you can really do is fill it and keep minitoring. Cracks on the outside are the big worry and if you are free of these then it’s more to do with climate than foundations.

Thanks both. That’s put my mind at ease! There was a big external crack but that hasn’t returned (you can see the silver of the expansion thing they put in) slightly, but I guess that’s it’s job to expand! The internal crack was fine over winter and reappeared this summer so I guess it seems likely to be climate related.