remove concrete floor?

[Fizzer]

We are in the midst of purchasing an old house which has damp on pretty much every wall downstairs. We've had the usual suspects in to quote to remedy the problem. Two seperate damp experts have recommended chemical DPC and tanking on one wall where the ground levels are high.

Total cost for this is about 4K according to the quotes

Having done a bit of research into older houses (and on the advice of our surveyor), it seems that the favoured approach to treating damp is to let it breath. The thinking being the concrete floor is the main cause.

So now we're looking at taking up the 1960's concrete floor and replacing it with a breathable alternative. We have no idea how big this job is, i.e. how long it would take, how much waste it would create and any complications we may face.

The total floor area is approx 35 sq.M any advice would be appreciated!

 

[Penners]

Have you used the forum's search facility on this one? I reckon there have been more threads on this topic than on any other.

Try searching on words like "damp" "concrete floor" and anything else that seems relevant. That'll give you plenty of bedtime reading!

 

[Anne]

I just did this, not because the house was damp just because the 70's concrete didn't belong and since we were doing the rooms, besides it was damp under there and who knows how long before it found the walls to move to. Anyway it will probably fill at least one skip and take about 2 days to come up depending on how thick it is and how well it was put down. What do you intend to replace the concrete with?

 

[Fizzer]

I'm thinking that limecrete would be an alternative:
http://www.limecrete.org.uk/limecrete_info.html

This site seems to think that we could even have underfloor heating whilst retaining a breathable floor. The theory being that this would reduce the amount of water being forced up the walls.

 

[Essex]

We completed, last year, the removal of 100sqm of concrete slab and replaced with breathing floor (breathing membrane, LECA, breathing membrane, limecrete slab, limescrete with Uponor 'wet' underfloor heating pipes and honed York sndstone).
House was damp and mouldy.
House is 15C timber frame.
We are very pleased with the result. Dry house, everything capable of breathing, looks beautiful. V expensive exercise but well worth doing. We did it ourselves. Excellent courses for lime from the Lime Centre,near Winchester

 

[another_richard]

Not wishing to hijack the thread but is it possible to drill holes into the concrete floor to allow the pressure to ease?

For example, to drill 10 cm air holes into the concrete where removing the whole floor is impractical?

We have exactly the same problem of the concrete 'slab' pushing the moisture up through the walls and I think rather than remove the lot drill spaced holes.

Any thoughts please?

 

[MdB]

People have mentioned before about just removing a strip of concrete around the walls and replacing it with lime so as to allow the floor to breath. I guess drilling holes would do the same thing but I guess you would need an awful lot of them to be worthwhile. I guess you would need an area a couple of times larger than the size of the damp patch on your wall at the very minimum.

 

[Fizzer]

V expensive exercise but well worth doing.

This worries me! We were quoted 4K for the modern dpc+dpm+tanking approach; discounting the underfloor heating. would taking up the floor be much more expensive?

 

[NT]

This worries me! We were quoted 4K for the modern dpc+dpm+tanking approach; discounting the underfloor heating. would taking up the floor be much more expensive?

You dont say if youre doing it yourself or getting tradespeople in. Big difference.

The 'more mixes' section here
http://wiki.diyfaq.org.uk/index.php?title=Mortar_Mixes
discusses some mortar additions. Although primarily about cement, most of these apply to lime as well. Might be of interest.


NT

 

[Fizzer]

NT
You dont say if youre doing it yourself or getting tradespeople in. Big difference.

The 'more mixes' section here
http://wiki.diyfaq.org.uk/index.php?title=Mortar_Mixes
discusses some mortar additions. Although primarily about cement, most of these apply to lime as well. Might be of interest.


NT

Thanks for the link
'There's more to mortar than what you thoughta. '
I like that

I'd be worried about laying a floor myself but we are planning to take the floor up ourselves.
We will try to get to the stage where we have taken all of the floor down to the required 8-10 inches below floor level and would probably get the experts in to lay the floor itself.

It's very difficult at this stage (before we have purchased) to decide which route to go down. Treating the damp affects so much of the other projects that we need to do (removing walls, installing central heating, rewiring, moving a bathroom, new kitchen - more on that lot later!!!) - we really need to get a plan/budget for the damp work before we can even think about the rest of it!

 

[MdB]

I've got similar damp problems due to two layers of concrete floor + plastic. I'm leaving it as is and trying to cure the damp by lowering ground levels outside and french draining to hopefully lower the water table a bit. This is something I can do myself and won't cost much. Is this route an option for you?

 

[Fizzer]

We're also going to do french drains on two sides due to high ground levels, we're expecting that to help a lot on those two sides. What's pretty clear is that all the walls of the house apart from a recent porch (which presumably has a dpc) have rising damp, even at the other end of the house to the high ground.

So we are assuming that 47 years of water build up from the concrete slab has pushed up into the walls throughout.

 

[Becka]

anyone have any advice about flooring over a concrete slab with a gap round the edge for breathing..? mine has this by pure accident (I thing the front wall was rebuilt narrower than the original) but the wood flooring guy refuses to quote unless I concrete over this area to prevent damp, I'm wary of doing this as in case that gap is prevent any damp happening (the house is remarkably dry considering the concrete floor gypsum plaster etc.. ) but I would really like a wood floor as the carpet really isn't practical and tiles would seem to cold so I'm a bit stuck, any ideas? raising the floor probably isn;t an option unless it was only by a very little bit as the height from the floor to the beams is only 6ft 6 as it is..