Depth of Foundation for Loadbearing Internal Wall

[Whatamess]

Hi

We have got to completely rebuild the inside of our lovely French house/ruin.

I have searched the internet but cannot find the information that I need.

Does anyone know how deep the foundations need to be to construct internal loadbearing walls?

Any info would be appreciated.

Thanks[:)]

[derf]

I am not a builder, but I think that you would normaly build your internal walls directly onto the concrete base/floor if you haven't got a concrete base to build on, i.e. earth floor and tiles , I would suggest that is were you should start.

[bejay]

Hi there

In the UK the basic general principle was that that the trench should be dug down to subsoil level. This is usually marked by a distinct change in colour and the depth varies according to local conditions. This is then inspected and approved by Building Control.. I don't believe this facility is available in france but I think this process wiil give you a good starting point. In the end though this sort of decision is down to local knowledge and experience. There is no 'official ' depth.

bj

[powerdesal]

The design of foundations is a structural engineers job. The size (depth, width etc) is dictated by (amongst other things) expected load, soil conditions, wall structure etc etc.

Get it wrong (as an amateur) and you could be building an unsafe structure.

[Dave&Olive]

[quote user="derf"]I am not a builder, but I think that you would normaly build your internal walls directly onto the concrete base/floor if you haven't got a concrete base to build on, i.e. earth floor and tiles , I would suggest that is were you should start.
[/quote]

hi ok

             first glad you are not one  ...a builder that is

    ok the footings should be the same depth as the original house .

 just think about this ... all houses move up and down with conditions /or over time  they call it subsidence and heave .so if you build it too good  so as it would never move and the house does ...you will get separation from where it joins the house ..too weak the same thing ....

 best is a good guestimate .... but it needs a footing for a load bearing wall . for an old stone house been up since seventeen ought spot, done most of its settlement best to go ott than under , I would even throw in a few refo bars for luck and tie it into the stone work where it meets the main walls

                        Dave

[BIG MAC]

It is down to the bearing capacity of the soils vs the imposed load.

Generally back in the day footings were of indiscriminate quality anything from building off the side of a felled tree through brick corbells to extensive stone / concrete plinths.

if you are looking for a typical average for two storey house building the 1200 to 1500mm in low plasticity clay or well compacted gravels poss deeper if in fill / peat / high plasticity clay.

I would joint to existing masonry via sleeved stainless steel dowels to allow a construction joint as likely you will use concrete which will expand at a different rate to stone.

I would imagine there will be French books of standard architects details which you could crib from to keep the Mairie happy if need be.

I wouldnt lift a 25ft rc beam however I would cast one in situ if I needed to.

hope this helps.

 

[Whatamess]

[8-)] Well, that has certainly given us a lot to think about guys!  Must admit, I find it all a bit confusing, but I am sure the OH will understand all the technical stuff.  The house is about 160 years old, so I guess it should be settled by now.  The floors that are there at the moment are concrete, (I think), and there is a cellar which will have to be filled in (because I don't like cellars!).

Think this is probably one of those situations where a lot of reading/research is required - got to get it right first time - don't want the whole structure falling down around our ears!

Thanks all.