Cracks around window (advice please)

28 Oct 2008
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United Kingdom

We've had some substantial work done on our current house in 2013. Part of the included a huge steel across the back of the property and lintels installed above the windows (they hadn't been fitted originally).

One of the bedroom windows - above where the huge steel was fitted - has some cracks around it. I have tried filling the cracks, sanding and painting but the cracks have re-appeared. To the bottom right of the window is a 'hairline' crack. Above the window, in the recess is a more substantial crack.

Can anyone suggest what is likely to be causing this and how to fix it.


Hairline crack:

Larger crack:
larger1.jpg larger2.jpg
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Anything visible on the outside of the walls?

Not an expert but that diagonal crack is a worry, it could indicate that the giant steel is moving downwards relative to the side wall. The other 2 pics I can't tell what the context is (as in where are the cracks relative to the window, steel, floor etc). Of course we have just had a very hot summer followed by rain so a bit of ground heave or shrinkage in the bricks/blocks wouldn't come as a complete surprise- keep an eye on them (try and find a measurable bit, mark and measure)- they may well go away come the winter.

Or they may not- are the building firm and SE who did the work still in business? Give them a ring.

As for crack filling (leave them til SE etc have had a look) you need something flexible for the diagonal one (not silicon, it won't paint properly). The other 2 I'd hide with a painted batten myself (screwed onto 1 side of the crack only so you can remove & inspect every so often)
Thanks for the reply. I wasn't too concerned about the diagonal crack.

The other 2 pics the crack is behind the blind (stripy material in the pics). I'll try to upload a window wide image...

Edited to add:
There are no cracks visible on the outside of the wall
Last edited:
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Typical causes of cracking after beam installs
  • Jacking the walls up too much and then they drop
  • Walls not packed with slate on the beam
  • Beam deflects too much under load
  • Shrinkage over several heating/cooling periods
Less common - beam undersized.

The head crack could relate to quality of the lintel install and some shrinkage

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