Vertical cracks under windows?

[inwood]

A neighbouring house has a ground floor window with a vertical crack through the brickwork below it. I was asked whether or not this was an issue but am at a loss to explain why the crack has occurred.

Now I've seen this one I've also noticed similar cracks on other properties (both brick and stone built).

The crack is only about three courses long, about 1-2mm wide and almost smack in the centre of the brickwork below the window. It goes through the bricks rather than following the mortar and doesn't appear to have affected the window frame itself (or internal plaster). It looks historic so I've suggested there's probably nothing to worry about but maybe get a structural engineer in.

Does anyone have an explanation for this type of crack? no other cracks appear above or around the window.

Any thoughts?

 

[MdB]

My guess (I know nothing about this really)

Wall either side of window has weight of wall above + roof on it and has sunk. Wall under window doesn't have any weight on it and hasn't sunk. Stress causes crack in centre of wall under window.

This should only apply to walls with poor foundations I guess.

 

[Pford75]

Could be that the window was installed without a lintel in place

 

[MdB]

Could be that the window was installed without a lintel in place

That would cause cracks above the window rather than below wouldn't it?

 

[Pford75]

It can cause both...you are right that mostly they are above...but in some cases (as with our previous property, they were below.

The other possibility is settlement which may have occurred at different rates under the window. Depends how recent the cracks look as to whether I would be concerned about it