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Who would check foundations are deep enough?

I am looking to extend over an existing cellar. I have asked a builder to come and take a look and although he found the cellar walls to be the same as the rest of the house, i.e. not single skin, he suggested we get 'permission to build' in terms of checking the depth of the foundations. However, upon investigating I do not know who I would need to contact. Who would carry this out and how much would I expect to pay?

2 Answers from MyBuilder Extension Builders

You need to have a trial hole dug, to inspect the existing foundations. This a hole which needs digging outside the external wall, around 500x500mm square. It should be dug until the top and bottom or foundations are visible. You can then take measurements and clarify construction. A good builder should be able to do this for you. Depending on how deep and what he has to dig through, expect a mornings labour and maybe hire of a impact drill if required. Hope this helps


Answered 14th Mar 2015

Firstly you need to appoint a structural engineer to guide you where to dig the trial pits, more than one maybe necessary, generally he will advise you on the correct sizes.
Once the builder has dug to the bottom of the foundations this will allow the structural engineer to obtain the information he needs to advise you accordingly.
The cost for this can be anywhere from £500 - £1000,
I hope this answers your question
Kind regards


Answered 10th Jan 2019

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