Best way to reduce damp in cellar

[Higgers]

Hello all,

Over the last few weeks I've been clearing out my cellar and have realised that if I get a decent shed I could move the rest of the cr@p out of there and turn it into a cinema/gaming room.

However, the humidity level in there is between 50 and 65 percent (depending on if it's been raining recently) so I need to damp proof it. My question is, what's the best way of damp proofing a cellar? I've read several posts in which people have had their cellars tanked, however, is there a way of preventing the damp reaching the cellar walls in the first place? For example, is it feasible to put a damp proof membrane on the outside of the cellar walls between the brickwork and the soil to stop water soaking into the brickwork from outside? Are there any other methods to deal with damp cellars?

Higgers.

[clockworks]

You could damp-proof the walls with an external membrane (or a waterproof coating), but it would still rise up through the floor. Exposing all the cellar walls might be a bit risky - your house might fall down!
Internal tanking is the best way to go, since, to be effective, the membrane has to be continuous.

65% isn't really high - some rooms in my reasonably damp-free house get over 70%. Have you tested the walls and floor with a damp detector?

[Higgers]

Originally Posted by clockworks

You could damp-proof the walls with an external membrane (or a waterproof coating), but it would still rise up through the floor.

That had occurred to me too. I thought that a possible way of dealing with that problem would be to break up the existing concrete floor, lay a membrane (and possibly some heat insulating material) and then lay a new concrete floor. Damp would still be able to penetrate where the floor meets the walls though.

Originally Posted by clockworks

Exposing all the cellar walls might be a bit risky - your house might fall down!

I don't think my wife would approve of that.

Originally Posted by clockworks

Internal tanking is the best way to go, since, to be effective, the membrane has to be continuous.

65% isn't really high - some rooms in my reasonably damp-free house get over 70%. Have you tested the walls and floor with a damp detector?

I've not tested the walls, I wouldn't know how to do it. Where can you buy/hire damp meters?

If the walls aren't too damp could I get a plasterer to come and plaster the walls as he would any other room in the house or would he have to put an additive into the plaster to prevent damp coming through the plaster? I don't imagine I'd be wall papering the cellar, I'd just emulsion the walls which I guess would help the walls breathe.

Higgers.

[paul1967]

there a plastic sheeting that goes on the walls and floor that has raised dimples so that there is a flow of air then you plaster board the walls put some insulation down and screed or lay concrete over it ,what you then get is a room in a room ,you can diy or get pros in, its easy to find about.

[clockworks]

Re-rendering the walls with waterproof mix, and re-laying the floor with a membrane will work - it's cured the damp in my old granite cottage (solid walls, and no damp course).
Re-plastering is messy, but you lose no space - the problem with "room within a room" methods.
I stripped off all the original plaster. My builder rendered the walls with a sand/cement mix using "SBS" waterproofer, then skimmed with multi-finish plaster. Modern vinyl paints don't "breathe", it's best to use a traditional lime wash if there is residual damp.

Damp meters are avaliable from good DIY/electrical suppliers. I got mine on eBay for about £15. It's a simple device with 2 prongs. It makes a noise - the damper the walls, the higher the tone.

[louishm]

i agree with clockworks, cement rendering will do the job, regarding the floor i had mine asphalted, i worked out cheaper and less messsy although the house stunk for about a day.
you didnt mention what was on the cellar walls at the moment i.e plaster or bare brick, if there is no ventilation down there it may be condensation and not damp, this is the problem i had in my cellar although a de-humidifier sorted that out.

[clockworks]

Tiling the floor is another option.
One room in my house had a damp floor, another had underfloor heating, which would be a pain to dig up and re-lay. I decided to tile the whole ground floor. I used porcelain tiles (stronger than ceramic, and totally impervious to water), and flexible waterproof adhesive. The adhesive was spread as a continuous layer.

It wasn't cheap - about £35 a square metre for materials - but, it should last forever.
If your existing concrete floor is sound (no flaking or crumbling), it might be worth considering tiles. I'd avoid ceramic tiles - although the ceramic facing is waterproof, the clay body normally isn't.