DIY Doctor UK DIY Forums

Hi there

I have a rising damp issue that I would really appreciate some advice on -

The small pantry cupboard adjoining my kitchen has a concrete floor. After heavy rain the floor is damp to the touch. The roof is sound, and there are no holes in the walls.

After rainy weather the floor becomes damp and then dries out slowly.

(The walls are in fact dry at the base. One wall is an external wall and I plan to cut a channel outside at the base and fill it with gravel. I'll paint the wall with Johnsons water seal for good measure as well.)

Can you help me to come up with a way to stop the damp coming through the floor?

I thought maybe I could chisel out the concrete to a certain depth, put some sort of membrane down and pour more concrete over it...?

katkin,
If you can cope with an increase in the floor level, once the concrete is dry apply two coats of water based bitumen paint and overconcrete with self- -leveling compound.
end

you can buy a bitumin paint for the floor,that will stop it.

Hi, thanks to you both for your replies!

This would certainly be easier than chiseling up the old concrete! Do you think it will matter that the damp will still be rising under the bitumen layer? Will it eventually ruin the concrete?

Sound like a plan though. Do you reckon it would last for a good number of years?

Best,

katkin

Hi

Bitumen will stop moisture getting through, will never stop it from happening but should prevent it getting through to floor surface.

SPUD1701 wrote:Hi

Bitumen will stop moisture getting through, will never stop it from happening but should prevent it getting through to floor surface.

Thanks SPUD1701

Yes, it's meant to be good stuff that bitumen. It's looking like the way to go. I'm just wondering whether it wouldn't be better to block the moisture at a lower level...

I mean, how long can concrete stand being saturated before it degrades? If not long then it might be worth chiseling the floor out afterall...

katkin;

the proper way to solve your problem would be to follow your idea - take up the concrete, lay a DPM underneath and re-concrete. However at a cost and probably not necessary.

Firstly obviously try to find the cause of the dampness. Is water ingressing in somewhere when it rains, in which case you could solve the problem and allow the floor to dry. Or has the floor never been dry due to no/failed D.P.M?

Concrete as a stand alone material can withstand high moisture levels and won't degrade and so if the dampness is a problem then you can cover with bitumen to seal it in, or asphalt it. What are the surrounding areas like (walls?)

Has the floor always been just conrete or has it ever had any kind of covering over it (tiles?)

katkin wrote:

SPUD1701 wrote:Hi

Bitumen will stop moisture getting through, will never stop it from happening but should prevent it getting through to floor surface.

Thanks SPUD1701

Yes, it's meant to be good stuff that bitumen. It's looking like the way to go. I'm just wondering whether it wouldn't be better to block the moisture at a lower level...

I mean, how long can concrete stand being saturated before it degrades? If not long then it might be worth chiseling the floor out afterall...

I would try the bitumen first - this should seal the floor, your concrete floor will be fine - if properly applied and sealed, all should be fine.

I would try the bitumen first - this should seal the floor, your concrete floor will be fine - if properly applied and sealed, all should be fine.[/quote]

Thanks Spud1701,

I'm grateful for your help. Someone mentioned 'pouring' asphalt onto it to me yesterday. I was under the impression that this was a solid substance you could buy in sheets and put on your shed roof etc?

Would 'pouring' this stuff on be better or should I stick to the bitumen?

Best,

katkin

katkin wrote:I would try the bitumen first - this should seal the floor, your concrete floor will be fine - if properly applied and sealed, all should be fine.

Thanks Spud1701,

I'm grateful for your help. Someone mentioned 'pouring' asphalt onto it to me yesterday. I was under the impression that this was a solid substance you could buy in sheets and put on your shed roof etc?

Would 'pouring' this stuff on be better or should I stick to the bitumen?

Best,

katkin[/quote]

Hi

Either would probably do, you are at this point just looking to seal the floor to stop moisture coming through, concrete floors will draw damp through them.