New Patio has caused a crack in house wall

Salopsian

https://forums.moneysavingexpert.com/discussion/comment/82162616#Comment_82162616

I did some research and see what you mean. If the corner has dropped then the cracks would be wider higher up the brickwork. But, they don't seem to be like that. Seems like the house has shifted sideways slightly at the bottom?

Eldi_Dos

@Salopsian

You describe the orginal patio as being in a bit of a mess, do you have any photo's of it before you started your work. That might help posters to have views on the cracks.

Salopsian

https://forums.moneysavingexpert.com/discussion/comment/82163541#Comment_82163541

Happy to, see attached. The patio is 3 years old here.

Salopsian

https://forums.moneysavingexpert.com/discussion/comment/82163441#Comment_82163441

Hi, I am in Shropshire, between Telford and Shrewsbury. It does get a fair amount of rain but nothing exceptional…

stuart45

Cracks with an even width are often caused by thermal expansion and contraction.

Section62

https://forums.moneysavingexpert.com/discussion/comment/82163524#Comment_82163524

If the corner has dropped then the cracks would be wider higher up the brickwork.

That isn't necessarily correct. Cracks of varying width suggest there is an element of rotation. The crack being wider at the top would be consistent with rotation around a point near the ground (but not always).

If a portion of the wall subsides downwards with no rotation then the crack can remain equal width along the whole length. As stuart45 pointed out earlier in the thread, it is possible you've got a stepped foundation, and if there is weakness at the step then you could get vertical subsidence with only limited rotation.

In another scenario, if a crack 'fans out' as it goes up the wall then you won't necessarily see a wider crack at the top - the sum of the smaller cracks might add up to the width of a 'wider' crack though.

The 'rules' about structural defects are typically just generalisations - there are so many factors involved that being sure about what is happening usually requires long-term monitoring (e.g. using a DEMEC gauge) to figure it out.

Eldi_Dos

@Salopsian

Your idea to get a drain survey done, with a camera, might be a good place to start to check possible causes.

Should not be to expensive or intrusive.

Salopsian

https://forums.moneysavingexpert.com/discussion/comment/82163541#Comment_82163541

this is better…

Salopsian

… there are so many factors involved that being sure about what is happening usually requires long-term monitoring (e.g. using a DEMEC gauge) to figure it out.

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Dear Section62 (sorry don't seem to be able to reply to your post directly?).

thanks, I understand what you mean, need proper investigation to find out the cause.

All the comments here have been really helpful to give me ideas about what might be going on.

Bigphil1474

OP, the 10 year warranty is usually an 8 year warranty starting in year 3 - the builder covers defects in the first 2 years (often from a snagging list), and after that the NHBC warranty kicks in. It's really just for bigger stuff though. If this turns out to be a big issue, the warranty should cover it, if it's not then it won't. I'm fairly sure I read somewhere that you are talking about defects costing >£1k for the NHBC warranty.