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Are my old foundations adequate for extension beams

Postby Bill101010 » Mon Aug 30, 2021 10:46 am



So we are doing an extension.
We need goal post type beams as shown in green.
The builder is going to put the upright beams on plates on top of the old footings which are about 300mm thick and not solid, you may be able to see in the picture they have bits of tile etc in them. This doesn’t fill me with confidence.
He is planning on leaving the wall marked in red in place.

My friend has a steel fixing firm and is providing my steels, when he came to survey the job he said we should have removed wall A marked in red and dug the footings back to the main wall so they was under the upright beams.

The structural engineer has never visited the job and done all calculations remotely, I tried 4 different structural engineers before I managed to get this one.
He said either is fine and it’s up to the contractor to decide.

The builders favourite words are “that will do” and “trust me it will be fine”
When we dug the footings everyone told me to shutter them but the builder said “don’t worry, they never cave in” then they caved in and we had to dig them again.

If I could get the structural engineer to visit and say it was ok then I’d be happy.

Obviously I’d rather not take wall A out and put the uprights on the existing footing as it will save me money but I really don’t want to regret anything in the future.

It’s a single storey flat roof extension.

Any advice would be greatly appreciated.
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Simply Build It

Postby stoneyboy » Tue Aug 31, 2021 9:51 pm

Hi bill101010,
You do not mention building control which is worrying - the changes you describe should have Building Regulations approval. I doubt very much that they would agree that the existing foundations are adequate.
Regards S
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