I have a 1930's semi. I want to knock the kitchen into the dining room BUT the internal wall holds up the 3rd bed joists, so an rsj is going in to solve that. One end of the beam will go into the rear wall, the other end is going to be supported by a wall built where the old dining room door was. So it's up with the floorboards, then can I build the wall off the oversite concrete beneath or must I punch my way through and if so, how deep must I dig down?
Building an internal supporting wall on top of oversite concrete???
- Thread starter DIYedboy
- Start date
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Dig down 1m.
Really?............the building regs dept and the structural engineer haven't made any stipulations at all for this part of my build. I realise you know your stuff Nose, but that's hugely excessive innit?.............(the area is in the centre of the house and the nearest outside wall is at least 12 feet away (frost heave/damp etc).
I have never dug a foundation for an internal wall that was not at the same depth as the rest (external walls). Why would it be?
You may be ok as long as you are down to decent ground. However, that may be more than a metre or it could be less.
You may be ok as long as you are down to decent ground. However, that may be more than a metre or it could be less.
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That's easily answered............the house sits on about 12" of foundations, therefore why dig more when all this 3foot long wall is going to do is to support one end of the rsj that supports bed 3 joists above? The only reason for metre deep foundations is to get beneath frost heave penetration.............there won't be any of that in the centre of the house!
Really?
Another myth is that if the existing house foundations are at a certain depth then it is ok to match. Wrong.
Ground conditions will dictate depth. Your BCO will inspect and approve.
Watching with interest
I used to have a 1930's house on clay where the oversite concrete was probably only intended to stop weeds or moles coming up through the floor above. When I cleaned out the builders rubbish, the broom lifted loose pebbles out, and the mix was very weak and crumbly. I hope that whatever was under the walls was a bit more substantial, they had stepped brick footings.
I used to have a 1930's house on clay where the oversite concrete was probably only intended to stop weeds or moles coming up through the floor above. When I cleaned out the builders rubbish, the broom lifted loose pebbles out, and the mix was very weak and crumbly. I hope that whatever was under the walls was a bit more substantial, they had stepped brick footings.
So Nose......, are you are saying that there is absolutely no escape and I MUST DIG A TRENCH for this wall which already abuts the existing wall between lounge and dining room which is intact and not knocked through (whose foundations are definitely not 3 feet deep) come what may, the only variable is how deep the inspector demands?
I've had a great idea (in my opinion).............why don't I insert a concrete lintel or RSJ beneath the floorboards that sits on the existing dining/ kitchen wall and on the other side let the lintel into the end of the wall between the lounge and dining room therefore no digging needed!!! then I build the wall on top of the lintel...............errr whatd'ya think?
As long as the BCO does not want you to dig a foundation suitability/test hole, then great!
When I removed a wall, and inserted a RSJ, the BCO required me to expose the foundations of the wall, on which the RSJ was going to sit, to ascertain whether it was sufficient.
The architect had just required an additional pier to support the RSJ without knowing what the foundations were like. As it happened the BCO was happy with the existing foundations, and no additional pier was needed.
The architect had just required an additional pier to support the RSJ without knowing what the foundations were like. As it happened the BCO was happy with the existing foundations, and no additional pier was needed.
I thought I might be able to bash this 'little job' out this weekend................BUT sadly, it seems I'm going to set myself up for a fall!.............I'd better totter off down the council, see what the nice regs man wants and do as he demands................If I dig a metre then concrete it in he won't have observed the depth, so I'll be stuck again.............or would a couple of photos with a tape down the hole be acceptable?
Our BCO wanted to actually see the hole. Maybe they're looking for something more than mere depth, such as type, condition of foundation, type, condition of subsoil, etc.
I'm adding this for anyone interested in doing this. I spoke to the building regs inspector today, he said that it is quite possible to bed a concrete lintel onto the oversite concrete then block up with 7Nm concrete blocks on top. My structural engineer needs to supply calcs to prove load bearing capability and it would be necessary to drill a hole to determine thickness of concrete where lintel is to go................thick concrete=good to go!!!!
D
Doggit
Can we get a couple of things straight. Am I right in thinking that there's a 3ft doorway where you need to put the new lintel, and you're going to brick the doorway up, and use the new wall to support the lintel. If that's the case, then can you put a steel over the doorway, and then dig a foot trench, to support the bricked up doorway.
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