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Q&As
Do we have to pay extra for trench boards?
The foundations of our new house are being built, but we have a problem with the contractor. He says he has to fix timber boarding in the trenches to support the sides because the soil is too loose, and he wants to be paid extra for this. Should we pay him, and what should it cost?
Answers
Supporting the sides of trenches is normally a risk that is assessed by a groundworks contractor when preparing his quote. Your contractor must have inspected the site before he quoted you and should really have included the cost of this work then.
However, you may consider it worthwhile to pay a nominal sum to
avoid him deciding to leave the site.
There are two kinds of earth support: close boarded and open boarded (they used to be called planking and strutting, respectively). Close boarding is used where the trench sides are not able to support themselves, such as in sand. Open boarding is used where it’s just loose earth that requires intermittent support. In clay, the sides of the trench would be self-supporting and would not need any boarding.
Close boarding costs about £10 per
sq m and £5 per sq m for open boarding.
