retrofitting a basement

[Jethro]

totally idle curiousity, but what would be involved if you wanted to have a basement ... obviously a bit of digging :-) but what structural aspects, and what planning ones ?

cheers

[Doctor Drivel]

Planning? It may come under permitted development. Best have one that does not go right to the house foundations - an inner basement - so the foundations do not move. It needs to be tanked and have air vents . A lot of mess, but if you are not living there and space is at a premium in your area then worth going for. The utilities, hobby rooms, storage can all be there. The staircase will take space from the ground floor. Make sure it is very well insulated.

You could run a heat pipe around the perimeter of the basement, which will cool and vent the house. Could be in the earth. Popular in Germany.

Some companies specialise in basements.

[Jethro]

i was wondering what effect removing that much earth would have on the rest, especially near the foundations ? I guess you could brace the resulting void with steel girders ? I presume by tanking you mean creating a waterproof seal to prevent flooding ? Never heard of a heat pipe ?

[Simon]

Founds need to be underpinned somehow, with concrete piles and a ring beam, girders etc. Job done a lot in expensive London houses. It you remove earth within a 45 degree cone under the founds, you are removing support. An "inner basement" could work it you had big house, but note there may be internal loadbearing walls with foundations too. Simon.

[Jules]

Ours runs under most of the house, and is all poured concrete walls of between 9" and 12" thick with a few 12x12" concrete pillars supporting the floors above. It's divided into three rooms, so there are also some walls down there helping to support the house above.

I suspect it'd be a difficult and expensive job to do that to a house after the fact; Drivel's idea of an 'inner' basement might be a lot easier to do.

cheers

Jules

[Dave Plowman (News)]

Well, converting existing cellars round here is the in thing. And even then requires what is effectively underpinning. They don't have the height required by modern regs. A neighbour had this done recently and the total bill was 80 grand. Including a rather nice kitchen.

[The Natural Philosopher]

I saw my ssisters house being build in germany with te mandatory cellar.

Essentially the cellar was a reinforced cast concrete box, inside a DPM inside a polystyrene box.

It WAS the footings!!

And therein lies your problem. You need to brace the footings, but also insulate the walls..and a styrene box inside the footings will not do that.

I would imagine one way to do it would be to dig as for underpinnings, deep down outside the wall, and add more concrete and some insulation outside the house, then back fill.

Inside, you need to essentially underpin the footings as you would normally - i.e. a section at a time, dig below the footings, shove in insulation, then concerte then DPM then more concrete.

Unless the house is so large that you can dig up a single room less about 3 feet, and cast a cellar inside that space..

Also, be ware of flooding issues. That German house got filled with raw sewage. Yes the sewers were below cellar level, but they blocked. People higher up the hill...

British sewers wont be. By and large, so saniflows to do the dirty work, and a STRONG possibility that a backed up sewer will render the house uninhabitable for weeks. Or make it a water free zone.

Personally, if I were building from scratch again, I'd do it for the hell of it, but retrofit? No WAY Jose..;-(

[The Natural Philosopher]

Thanks for confirming my suspicions.

And do people really do it? London eh? where horizontal space is priceless..and people have more money than sense..

[Rob G]

=A0 London SW

There was mention of this being done in London. I have a cousin married to one of the 'much money and possibly no sense ' brigade and they had this done. The guy is an oenophile and not only did they go down to create a room under the house but he got them to go down yet further for a wine cellar - only they met the Thames coming in to meet them !

Rob

[Mark]

Its very fashionable in London,

not without the occasional problem, this was just round the corner from a house I own in Battersea.

[Dave Plowman (News)]

I could see the reasons for it when prices were sky high - just think of the costs if selling to buy something that bit bigger. Other thing is most of the houses round here are a similar size - until you go to the huge ones. So if you've got kids at a school you like etc or just want to stay in the area it might make sense.

[Rob G]

=A0 London SW

This one didn't make that sense as they were both retired - the only sense was accommodating grandchildren !

[Dave Plowman (News)]

Could be they couldn't afford it till now. ;-)

The house that backs into here is the same. Fabulous loft conversion going across the rear addition too. Beautifully done - looks like the house was built with it. Basement conversion too - and a huge architect designed conservatory. They've spent more on the house than it would be worth without. And their kids have just left home.

It's unusual round here in having a garage - due to being a corner plot. And they've converted that into an office or something. The driveway isn't really long enough to take a car. Although they still park theirs on it. Overhanging the pavement by a foot or so.

[Owain]

If you have a two storey house and you add a basement it becomes a 3- storey one, and additional fire precautions may apply.

Owain

[Dave Plowman (News)]

That doesn't make sense since it's exit distance (therefore time) in event of a fire that matters. And in this respect a basement will be the same as a first floor?

[Jules]

Or they had descructive kids, so waited until they'd left before they invested time and money doing it how they wanted it.

Hmm, nip round there with a gas-axe and lop off the end 12" or so. That'll learn 'em. :-)

[Hugo Nebula]

On Thu, 10 Sep 2009 13:39:27 +0100, a certain chimpanzee, "Dave Plowman (News)" randomly hit the keyboard and produced:

Around here, it's also the thing. But 'around here' is the shitty parts of a large Northern city, now inhabited by students. The business model of the owners of the student houses (after removing all the supporting structure from the roof void to squeeze a couple of bedrooms up there) is to cram an extra couple of bedrooms into the sub-floor void by digging down below the foundations, lay a concrete slab on a notional amount of insulation on a damp-proof membrane, and slap a thin coat of a waterproof render on the walls. Part of their business model relies on a) hoping Building Control don't drive past, and b) not speaking English when they do.

[Pete Verdon]

I lived in one of those in Leamington. My cellar room was actually not bad, since I'm not very tall (the other guys in the house had to stoop when they came in). It was a huge room, being basically the entire floor area of the house, though I did have the gas meter overhanging one end of the sofa that was in there. This was also the room I mentioned a while ago where the NTL installer put the cable in through the extractor fan.

The bad room in that house was the loft; it had been "converted" with a bit of plasterboard and a Velux window, but an actual staircase was apparently too much effort so the hatch and aluminium ladder remained. The ladder blocked the door into one of the other rooms, so had to be moved when not in use. There was no real furniture up there (couldn't get it through the hatch, I guess) so the girl who lived there kept most of her clothes in the big old wardrobe on the landing and just took up the next day's stuff when she went to bed. She didn't have the whole wardrobe to herself though - despite being a freestanding item of furniture, half of it had been used to contain the hot water tank.

How she never fell off the ladder and down the stairwell after returning from the pub, I do not know.

Still, it was cheap (my palatial room was £33 a week in 2003 IIRC) and we had a lot of fun living there.

Pete

[tim.....]

I had a friend who had a drive like this

the warden would come around about once a week and ticket them

tim

[Dave Plowman (News)]

The privatized 'wardens' round here haven't got the authority to do that.