Author Topic: Moisture on concrete floor under rug  (Read 512 times)


  • Pencil Stache
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Moisture on concrete floor under rug
« on: November 17, 2018, 10:27:56 AM »
Just bought a new house.  The finished basement sometimes has a mild mildew smell to it. 

There is a fair amount of insulation behind the drywall, but no vapor barrier.  All of the floor is carpeted, hard to tell what is under, but one small region has a part where the i can pull the carpet back a little bit, and there is some moist concrete.  We just put in a large dehumidifer to hopefully address this.  From what i can tell, most of the floor is concrete with plywood on top of it, and then rug.  No vapor barrier here either.

Any thoughts?
Is no vapor barrier a disaster in the mix?  Will powerful dehumidifiers do the trick?  FWIW, it has been a mich wetter year than usual.
« Last Edit: November 17, 2018, 12:26:43 PM by Case »


  • Handlebar Stache
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Re: Moisture on concrete floor under rug
« Reply #1 on: November 17, 2018, 11:07:19 AM »
I hope you put in a DEhumidifier.

Damp basements are very common in many areas.


  • Pencil Stache
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Re: Moisture on concrete floor under rug
« Reply #2 on: November 17, 2018, 12:27:19 PM »
Yep! An unfortunate typo


  • Stubble
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Re: Moisture on concrete floor under rug
« Reply #3 on: November 18, 2018, 09:00:20 AM »
Unfortunately, you will most likely need to do some more investigating. Moisture in a basement is one of those problems that can run the gamut from "Meh...nothing to worry about..." to " Honey, we need to sell both children to pay for the repairs."

The lack of vapor barrier could be a concern but not automatically the culprit. I'm assuming the basement was permitted?

This is what I would do in your situation:

1) Check that your lot is graded away from the foundation and your gutters and downspouts are clean, functional and ALSO extend away from the foundation. This is the easiest to remedy.

2) Do you have a a sump pump? Check the pit and see if it has water in, make sure the pump is functional and the drainage pipe isn't blocked.

3) Check around (building department, local builders) and see if your area is known for having a high water table or if others in your neighborhood have had basement issues. If yes, sometimes a sump pump / drain tile can help, although retrofitting these can be fun.

4) There are a number of really good basement water proofing systems available. However the do involved excavating down to the footers. This gets really expensive to pay a contractor to do it. If you're handy, you can do this yourself, but it's a lot of dirty, nasty, hard work and you'll need to be familiar with exactly how the system should be installed otherwise all the work could be for nothing.

I would let the dehumidifier do it's thing and check gutters/downspouts/grading first. Changes are very good these will help the issue. If not, pay a PE to come in a do an assessment and give you your options.

My .02

« Last Edit: November 18, 2018, 09:04:02 AM by CatamaranSailor »