Friday, March 30, 2012
How To Spot Subsidence (and It's Potential Causes)
As you can see in the image to the left the tree (bush?) is growing right next to the brick wall, judging by the tilt it's quite easy to imaging the roots of the plant going under the foundations of the building.
If you zoom in to the corner of the building you'll see that the brick wall next to the bush has been undermined and has dropped by a few millimetres - this causes the practically-vertical crack down the side of the building about half-a-brick in.
As the bush grows it will cause more and more damage to the foundations (the drop it quite likely due to it falling down due to the bush absorbing moisture from the clay-rich soil).
The solution would seem to be to remove the bush and see if that stops the subsidence (it's a garage not a house). Depending on the rate of subsidence it's important to work out the risks involved in any "wait and see" approach.
Clearly the motto here is to check for inappropriate plantings like this every few years!