Damp under concrete basement floor linoleum

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Old 02-05-14, 08:02 PM
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Damp under concrete basement floor linoleum

I've recently bought a 1950s house with double brick, concrete walls below the ground and concrete fall. I've recently noticed dampness under the linoleum in the basement laundry. The laundry also houses the furnace. The house is in Toronto ON.

I have noticed signs of mould on the skirting boards in the finished basement which is nearby the laundry.

Is this dampness a sign of moisture coming up through the concrete and getting stopped by the linoleum (vapour barrier?). Should i be worried?

The laundry is currently unfinished and i've been advised to insulate and finish it by a recent energy audit. Will doing this, applying vapour barriers etc fix the problem?

I was thinking of removing the linoleum and letting the damp dry out and see if it returns. Would this be a good idea.

Also i've also noticed that the drain in the basement doesn't have a U-bend (there's a draft coming out of it), could this have anything to do with the dampness?

thanks for any tips.

oman
 
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Old 02-05-14, 09:08 PM
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Hi oman,
"Is this dampness a sign of moisture coming up through the concrete and getting stopped by the linoleum (vapour barrier?). Should i be worried?" Yes and yes. I'll add a link that discusses similar.
BSI-003: Concrete Floor Problems — Building Science Information

Vapor barriers over any concrete in a basement are not good. If you block the vapor flow it will force the moisture level to accumulate until it is as wet just behind the VB as it is in the surrounding ground. Eliminating the VB allows that extremely small amount of moisture vapor to evaporate to the inside (since it cant evaporate to the outside) and once inside the home it has little effect.

Water leaks are a different issue and need to be addressed mostly from the outside.

Wherever that sump is opening to the atmosphere it should not have an open path into your basement, especially if it drains to some sewer system. In any case, you should test for radon and most likely seal the top of the sump and install at least a passive vent system. If radon levels are high and the passive solution is not sufficient, then a fan can be added.
State Radon Contacts: New York | Radon | US Environmental Protection Agency

Bud
 
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Old 02-07-14, 04:52 PM
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Thanks for the detailed reply Bud,

While i don't believe my slab would have been done on sand (1950s?) it does sound like the vapour is being trapped by the lino. I'll start by removing the lino and perhaps considering tiling down there using a Dimpled Plastic Sheet Membrane as indicated in Photograph 11 of your first link.

Thanks for the tip on radon, better get that tested. I was actually more concerend about the heat loss. I should probably be concerned about sewer backup as well so perhaps i'll try and hit all 3 on the head at the same time

cheers
oman
 
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