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Unconverted basement - anyone any experience please?

(11 Posts)
Zimm Sun 26-Jun-11 09:16:40

We are thinking of a buying a 3 bed house with an unconverted basement which measures 16 by 10 feet. It clearly has some damp. Can anyone advise if we would need to get it converted ASAP to avoid the damp getting worse or if we could leave it for a while as we won't really have the money to do it straight away. If anyone has had a basement converted and can advise on approx cost that would be great too.

pooka Sun 26-Jun-11 09:23:27

I wouldmthink that it may be worthwhile having the damp looked at professionally and some programme of works to halt it.

We converted our old coal cellar into a utility room with loo and storage shortly after we moved in. Didn't have damp problem though - being a coal cellar I think it was built to withstand damp to a certain extent.

Needed new staircase and then it was tanked to comply with regs and stop damp in future. Cost about 10k all in, including macerator that could cope with loo and washing machine outflow. Have to say was the best thing we did in terms of raw adding value. More room in kitchen and ample coat/boot/utility storage.

Zimm Sun 26-Jun-11 09:28:27

Thanks Pooka. We would be going for a full structural so we know the extent of the problem and would probably add a specialist damp survey to that.

dadof2ofthem Sun 26-Jun-11 11:17:55

are you actually digging out under the foundations zimm ?

dadof2ofthem Sun 26-Jun-11 11:22:09

i dug our cellar out in our old house, under foundations and everything, it was a gargantuan job!
the front and back walls got an extra skin of bricks to keep the damp out, we used 'kalksandsteen' thats dutch , i'm not sure what there called in english, but the're whitish bricks and more chalky that concreate bricks, the're a great protector against damp.

Zimm Sun 26-Jun-11 11:23:39

Hi - thanks for response. No digging needed. Would be existing mould elimination, damp proofing, plastering, carpet etc.

mousymouse Sun 26-Jun-11 11:27:27

'kalksandsteen' is lime or lime brick stone btw.

nocake Sun 26-Jun-11 19:48:43

We live in a 150 year old house with a cellar that is damp in places. It's been damp since the house was built so there's no reason to assume that yours is a problem. As long as you have a damp proof course above ground level the damp should stay in the cellar. We use our cellar for all sorts of stuff, including storing paperwork, and as long as you keep stuff in plastic boxes, away from the damp patches there's no problem.

If you do decide to have it sealed or tanked you need to be aware that trapping the damp in the walls can cause them to deteroriate, particularly if it's an old house. The best way to do it is to fit a membrane to the walls and floor that allows water to drain between the membrane and the wall. You'll then need a drain or a pumped sump to get rid of the water.

Zimm Mon 27-Jun-11 15:56:55

Thanks nocake - very useful.

PigletJohn Tue 28-Jun-11 10:16:49

if it is a cellar rather than a basement, it is expected to be damp. It probably has no proper floor and inadequate headroom. If you are going to convert it to a habitable room you will usually have to lay a new concrete floor with DPM and insulation; the thickness of which will mean that the headroom is even less, so you normally have to dig out the floor some more first. Unless the walls of the house have deep foundations, this will mean digging below the safe level so the walls will need to be underpinned first. It is probably below the level of your drains so you will need pumps to take any sewage or plumbing waste out. It can of course all be done.

Do you hear the words "Difficult" and "Expensive?"

PigletJohn Tue 28-Jun-11 10:42:56


to control the damp in the short term, ventilation will usually do the trick and is cheap and easy. You need ventilation on at least two sides of the building so there is a cross-flow of air. As a rule of thumb start with an air brick every metre. Clean the dirt and cobwebs out of any existing ventilation. Don't be tempted to block them "to keep draughts out." It is possible to run plastic ducts under or through adjacent floors to achieve cross flow, though this is more work. If some dummy has built an extension or poured a concrete floor in an adjacent room this may have prevented ventilation crossflow so you will need to reinstate it or use extractors. If there is an old chimney you can get access to, this will generally draw air up and out. As long as the ventilation can take the damp away faster than it can permeate through the walls and floor it will not be too bad. Search for extra any sources of water such as broken drains, water pipes, leaking downpipes or dripping gutters and fix them.

Never drape wet washing around a room unless you want it to be damp.

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