Steel and foundation design requirements

7 Sep 2018
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United Kingdom
god do these problems never end.

I am building a small lean to extension, this will mean the main house will be opened up and a new steel put in situ.

Lots of issues surrounding that, god a SE who did calculations with lack of detail so BC couldn’t understand, the se makes no mention of what the piers holding the steels will need underneath them. BC have questioned the lack of addressing of support in the report, SE days that’s not his job, it’s the BC, so stuck in the middle.

On here it seems to be the SE. If left toBC I think they would have them underpinned! It’s 2 5.7 steel.
Luckily the steel will run along the old foundation wall so there should be 1 metre of concrete under, if it held up the wall and roof, surely it should now hold up the steel. Anyway who do I get to tell me if the foundation needs further enforcement, for the steel.
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He has finally added detail re pier, size and blocks but not what should be underneath it,
structural engineer IMO.
Generally a structural engineer will visit site and look at the house founds -if he cant see enough he might ask for some digging down the side of the foundation to see.

It might need underpinning -a large opening removes a section of support on the foundation, so all that load then gets concentrated under the piers -probably fine though if you have a decent house foundation.
Assuming its some sort of goal post arrangement, I'd work on the basis that the supports will need to be on a 1 - 1.5M cubed block of concrete, which will need to be dug out. When I had this done, the architect subbed to a Structural Engineer who specified the steel work and supports. Definitely not the building control inspectors responsibility - he/she just says if he's satisfied or not and what information he needs. He's not responsible for design, only approval.
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It is 2 rsj sitting on 2 brick piers 330 by 330, tied into walls.

This is an ol external wall where we have just had it opened out, so far as we know those foundations were the usual 1 metre by 600. Think there is an earlier post which states no one else has ever had to enforce foundations, but yes it does appear the SE role
Do you mean Expose, not Enforce?

I had to expose and then underpin mine due to crap foundations on the original house.
Hope that’s not necessary, this is more about whose role it is to give that opinion, or advice. I have had to go to a different SE. This one just said wasn’t up to him, speak to BC. Well they are likely to go underpin route.

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