Underpinning and foundations???

[liam546]

Ive recently installed an RSJ which sits on two steel posts. One of these posts sits on the top of my celler wall.

I want to lower my celler floor and therefore do some underpinning. I will do this at a later date, but for now I'd like to just do the section under the steel beam load as I have acrow props up so want to do just this bit now.

My celler is about 6ft hight from earth floor to ceiling joist. I would like about 7 or 8 ft ceiling height eventually

My question is what is the requires footing I need to dig below my new floor level? I've read in new houses it's a meter but that would mean I have to dig down about 1-2ft initially (to get to the new floor level) then another meter for the new footing.

Is this correct? [/list]

 

[Blagard]

I think it very unlikely you would have to dig that deep in a cellar situation. But I can't say how deep you will have to go because the work needs to be designed by a structural engineer and in compliance with the Building Regulations. This will involve more that just consideration of foundation depth but stability of the structure as a whole.

The following web site may help you better understand where you are thinking of going

http://www.homebuilding.co.uk/advice/existing-homes/converting-basement/guide

In particular the advice:

"It is best to make a Full Plans Application for a cellar conversion, rather than to follow the Building Notice procedure, as this allows all design details to be resolved in advance of the work."

 

[liam546]

Thank you very much for the advice......I spoke with North Hertfordshire building control today and spoke to one of their seveyors. He said I don't need to go down more than a foot as I'm already in the celler and my house is on chalk, already a solid substrate unlike clay.

.....but he did say if I'm looking to convert celler it's advisable to submit a full plans application such as your advice. So thanks very much