01When you may need one.
- Clay soils, especially near trees. Clay shrinks and swells, and foundation depth near trees depends on how much. Testing the clay can avoid over-deep foundations.
- Made ground or fill, which is common on older and former industrial land.
- Coal mining areas, where your engineer may want to know more about the ground.
- A soakaway for rainwater, where building control will usually want a soakaway test.
There is no single national rule that every extension needs a soil test. It is decided case by case.
02What it involves.
For most extensions it is a small job: a trial pit or a window sample near the new foundations, logged and sampled, with laboratory tests on the clay if needed. In tight back gardens we can use hand-held sampling kit.
03Quick answers.
Do I need a soil test for my extension?
Often, yes, especially on clay, near trees, on made ground or in coal mining areas. Your engineer or building control will tell you, and we can do the work quickly.
How long does it take?
The site work for an extension is usually short, with laboratory results following.
