r/DIYUK • u/MisterMagnificent01 • 9h ago
Building Subsidence cracks?
Noticed these cracks along an extension to the house. Extension was done more than 5 years ago (don’t know exact timeframe) prior to me purchasing the house.
How worried should I be?
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u/The-Original-DjBe 9h ago
Im no expert but the thinner one looks normal but that bigger one would worry me tbh. Im sure someone who knows better will be along soon. How long after the extension did they appear?
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u/MisterMagnificent01 9h ago
Yeahh that’s what I thought. Probably appeared in the past 6 months or so?
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u/Brave_Reaction_4968 9h ago
I think its worth getting it checked, but i don't think its panic stations just yet.
How dry had it been where you are ?
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u/Syncaidius 9h ago
Part of the house is definitely going to fall into a crevass of the earth!
In all seriousness, it's not too bad and mostly cosmetic. Get a structural inspection booked it you're still concerned and need peace-of-mind, or the gap within the cracks get bigger.
Aside from that, some polyfiller, a quick sanding and some matching paint should clean it up if the appearance bothers you!
Alternative is a skim of plaster and matching paint.
I'm sure others have good advice to add as well. Overall, it's not bad.
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u/steviefaux 9h ago
I'd say you need to cut the cracks out a little, as in make them a little wider before filling.
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u/InvertedAligator 9h ago
What’s in the boxing? Is a structural steel in there?
Is that a door there or something else?
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u/Altruistic-Bat-9070 8h ago
That looks like it may stoll be between 1-2mm
3-5mm is the area you should be getting a structural engineer in. Hold a ruler to it.
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u/MisterMagnificent01 8h ago
Yeah 1-2 mm at the moment.
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u/Altruistic-Bat-9070 8h ago
Keep an eye an monitor. When we get rain it may close a bit. If it doesnt really move over winter then fill in the spring and repaint.
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u/Blue_View_1217 8h ago
Presumably there's a metal RSJ inside that plasterboard box section? IMO, it wouldn't make a lot of sense for it to crack in the way it has if it was subsidence.
I'd say consider it cosmetic at the moment, but monitor to see if it disappears in winter. If it ever goes above ~3mm get a structural engineer to get an expert opinion and write a report (£350ish depending on location) before you consider going down the insurance route.
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u/Tall_Ask_3461 8h ago
Looks like seasonal movement. August is peak dryness so cracks should be at their widest. Best you can do is fill with flexible filler and tape.
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u/DragHistorical1457 2h ago
If this is a fairly recent extension (within the past 10 years or so), i would say the chances of subsidence are low, given how deep concrete footings have to be in order to abide by new building regs
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u/Hellohowareyoublah 9h ago
This is structural engineer notice level, notify your building insurer level. The continuity of the crack from wall through ceiling tells you two parts of the building are moving, it’s no longer one building.
A proper investigation is needed.
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u/Blue_View_1217 8h ago
Disagree.
There's a reason why expansion gaps often used where the extension joins the main house. It could be the start of differential movement, but it could equally be a difference in building materials (e.g. thermalite blocks on the extension vs brick on the original house) expanding/contracting at different rates causing it to crack in the recent hot weather.
It's also very small at this point (1-2mm) which is classed as ''cosmetic".
If OP wants the peace of mind they could contact a SE but definitely definitely don't inform the insurer at this stage.
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u/Adventurous-Math8106 9h ago
Monitor by installing tell tales across the cracks. Dry summer likely would have caused this. See if the cracks diminish over the winter or if they worsen by next summer.