Hello all, I'm new to this forum. My house was built in 1997 by myself with the exception of the poured concrete basement and slab. I am in a clay area and the house is primarily heated with a wood stove in the basement. Recently I was doing some work close to the stove. In the area was a plastic boot mat sitting directly on the floor, when I moved it there was water under it. This is in the middle of the basement, 2 feet behind the stove where the concrete gets warm. I have also noticed in the past that when I move some plastic totes that there is an outline of the tote on the concrete, but no visible water. It's February now and I'm in northern Ontario so it hasn't rained too much.I don't know if the contractor put anything under the slab and I really don't want to pull it up. Should I be pushing the panic button?
Sweating Concrete Slab/Floor
- Thread starter erikz
- Start date
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Possibly!!, Regardless of where you live, if you have a concrete slab built in 97' it should have a DPM or some sort of membrane underneath. moisture is comeing through the slab via either a faulty membrane or no mebrane at all..
Hi
If you did not have a dpm installed you would be having serious problems with ground water ingress and you would be paddling/swimming in ground water!
Do you remember if the contractor put in a dpm, this would have been quite an onerous task or it may be that a waterproofing compound was added to the concrete during its mixing.
Only problem with additives they may well stop water, put they may not be moisture/vapour resistant and this is where your problem may well lie! Plastic and rubber compounds are very vapour resistant and where you have left these items in contact with the concrete sweating will occur.
I assume at this time that the damp patches dry out after the plastic has been removed?
The easiest solution to overcome these problems would be to use a coir matting which is breathable (or any other breathable product) for the boot mat and any other area's. You won't notice the damp in other exposed area's as the surface vapour will evaporate in the warm environment. Whatever you do - do not go laying plastic/vinyl/rubber tiles over the floor - the vapour pressure will cause the floor coverings to bubble up and you will be going backwards!
If you need to solve the problem the only solutions I know off is to either use a build up of 3 x 1.5mm coats of epoxy resin with sand blinding on final coat to give a dressing ready to receive a latex screed, the other option is asphalt!
Regards
If you did not have a dpm installed you would be having serious problems with ground water ingress and you would be paddling/swimming in ground water!
Do you remember if the contractor put in a dpm, this would have been quite an onerous task or it may be that a waterproofing compound was added to the concrete during its mixing.
Only problem with additives they may well stop water, put they may not be moisture/vapour resistant and this is where your problem may well lie! Plastic and rubber compounds are very vapour resistant and where you have left these items in contact with the concrete sweating will occur.
I assume at this time that the damp patches dry out after the plastic has been removed?
The easiest solution to overcome these problems would be to use a coir matting which is breathable (or any other breathable product) for the boot mat and any other area's. You won't notice the damp in other exposed area's as the surface vapour will evaporate in the warm environment. Whatever you do - do not go laying plastic/vinyl/rubber tiles over the floor - the vapour pressure will cause the floor coverings to bubble up and you will be going backwards!
If you need to solve the problem the only solutions I know off is to either use a build up of 3 x 1.5mm coats of epoxy resin with sand blinding on final coat to give a dressing ready to receive a latex screed, the other option is asphalt!
Regards
www.diychatroom.com
You need to go on here, as basements are a specialised job not usually built here. Negative repairs don't usually work.
You need to go on here, as basements are a specialised job not usually built here. Negative repairs don't usually work.
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Hi
I forgot to mention earlier:- If you do decide to treat only the floor you will likely find that you get some salt or damp staining around the perimeter wall where it abuts the floor due to the vapour/moisture being trapped and like water the vapour will eventually take the path of least resistance, which will be the perimeter edge of the building!
If this had been a new build you would expect a damp proof membrane (tanking) to be taken across the floor and up the walls where it would join the perimeter dpc thereby ensuring that any vapour or moisture stays trapped behind an impervious barrier.
So initially, I would suggest that you try the coir matting route, as an alternative - clay floor tiles work well, saying that, if at a later date you decided to cover the clay tiles because the floor was cold, you would end up with the same problem that you are now encountering - being forewarned is possibly the better remedy than living in hindsight!
Regards
I forgot to mention earlier:- If you do decide to treat only the floor you will likely find that you get some salt or damp staining around the perimeter wall where it abuts the floor due to the vapour/moisture being trapped and like water the vapour will eventually take the path of least resistance, which will be the perimeter edge of the building!
If this had been a new build you would expect a damp proof membrane (tanking) to be taken across the floor and up the walls where it would join the perimeter dpc thereby ensuring that any vapour or moisture stays trapped behind an impervious barrier.
So initially, I would suggest that you try the coir matting route, as an alternative - clay floor tiles work well, saying that, if at a later date you decided to cover the clay tiles because the floor was cold, you would end up with the same problem that you are now encountering - being forewarned is possibly the better remedy than living in hindsight!
Regards
I really don't think so. You are getting damp patches appearing under items that will not allow water vapour to escape. In extreme cases a film of water.
Even if a DPM was installed it could easily be less than perfect and allowing element of dampness to get into the concrete. So long as the floor is not sealed any further and continues to breathe I would suggest any plastic sheet materials and similar are not put directly on the floor. The problem could also be simply condensation. Especially if the basement is not very well ventilated.
If you can find out what the level of the local water table is you may be able to determine the level of risk for the future. i.e. if the basement floor is lower than the water table then you should have no serious concerns as this is when any problems are magnified and your floor and walls are in effect acting as a dam! If the water table level is below your basement floor, there is a risk that if/when the level rises you may find you actually have a pool of water in the basement.
If you have plans to change the use of the basement, the first thing I would do is to ensure that ventilation is adequate and that all issues that may give rise to condensation are eliminated. If the problem remains only then would you need to consider the options dealing with waterproofing issues.
Hi
As per Blagard's comment - There's no point in panacking as you have a relatively minor problem and now that you are aware of the cause of the problem you are halfway towards coming up with a cunning plan and can decide the best solution to suit your needs - always best to go for the simplest and hopefully low cost option first - i.e. use coir matting - a hell of a lot cheaper than the other options and it will hide the problem!!
Out of sight is out of mind!!! As previously stated don't go putting a vinyl, plastic or rubber floor covering down (even if it is stuck down) - you will only live to regret it!!
Regards
As per Blagard's comment - There's no point in panacking as you have a relatively minor problem and now that you are aware of the cause of the problem you are halfway towards coming up with a cunning plan and can decide the best solution to suit your needs - always best to go for the simplest and hopefully low cost option first - i.e. use coir matting - a hell of a lot cheaper than the other options and it will hide the problem!!
Out of sight is out of mind!!! As previously stated don't go putting a vinyl, plastic or rubber floor covering down (even if it is stuck down) - you will only live to regret it!!
Regards
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