How far can i dig down in my cellar?

[prbaxter]

I have a cellar, in a semi detached. The main void has been floored with some sort of cement type of mixture. you cannot stand up in the cellar, you have to walk around with your back all hunched over and it's not a working area by no means - which is a shame.

The past weekend was spent removing all the loose bricks, rubble and soil from the adjoining small void. There is no floor in here so i could just keep digging right down into the earth which would be good if we could make the area tall enough to stand in.

I would probably need to dig down another foot. Would this cause any problems with the stability of the house? When should i stop digging? How can i tell where the foundations start and what are the dangers of digging too deep.

If i can successfully go deeper in this void, then i may consider doing the same to the main cellar area - which is much larger, but would give a fantastic working space.

P

 

[mnb]

Dont do any digging without professional advice on site i.e. a builder or structural eng. One has to see the actual conditions before making a judgement. I've seen a number of catastrophic diy or ill experienced "builders" botch - ups. Pay someone to prepare section and plan views of what exists and what can safely be proposed.
I know of examples where the owner /diyer seemed to have dug out a cellar safely but over time or during a mortgage survey cracks and sagging became apparent.
Anyway, test holes must be dug prior to any major recommendations or work.

 

[prbaxter]

Ok, that is sensible and useful. There is still a mound of earth in the cellar which is higher than everywhere else in the other voids - looks like it was the dumping ground when the other areas were leveled. I should be ok to clear that out but i will stop once it is pretty much back down to the level of the resurfaced area.

I'll get a builder in to get a quote.

 

[Tozzy]

Can't you raise the ceiling?

I have dug down about 6 inches, but then again, this 6 inch depth is now occupied by a sub base and screed. Therefore, in effect, the final floor level has not been lowered.

I know the foundations only go down so far; usually about a foot? But, you don't really want to go down that much unless you're prepared to jeopardise the structure of the house. Perhaps get a quote from a professional and experienced builder (not aiming that remark at you, but at those cowboy builders that are around ). If you saw my thread in DIY Disasters, you'll know what I mean .

 

[prbaxter]

The ceiling comprises of joists and floorboards (of the floor above) so i cannot raise the ceiling without lifting the kitchen.

I aim to fill the gaps between the joists and rafters with insulation foam (you know, the loft stuff) and then cover with board. This will help keep lots of heat in our cold kitchen. Most of the heat seems to just leak out through the floor in to the cellar. the floor is always cold. This of course will lower head space further slightly.

 

[jeds]

You also need planning permission to increase the depth of a cellar.

 

[Teahead]

You must also ensure that the ground level in the house next door is the same as it will be unlikely that the walls have been designed as earth retaining structures. You must not go any lower than 300mm above the underside level of the existing foundations (unless you want to go to the time and expense of underpinning the house.

Another thing to take account of is the existing ground water level, you could dig down just to find that you have created an basement duck pond