I just moved into a rented apartment.
The bedroom closet/office has carpeting which is mildewed.
It noticeably smells offensive and I am allergic to mold.


We looked under the carpet.
At the edges, we can see that 60s style ceramic tiling was cut away,
so the room likely used to be a master bathroom.
Currently, it is layered as carpet, then padding, and then exposed floor.
Beneath that is the next floor down: an unfinished basement.

The unfinished basement is very moist,
so we assume that the moisture from the unfinished basement
is making its way through the flooring
and soaking into the carpet padding and the carpet,
creating a breeding ground for mold or mildew.

We checked the basement.
(The floor is concrete with roughly 1/8" layer of dirt.
Does this suggest flooding in the past?) The walls are jagged concrete
which is brittle and crumbs off to the touch.

More related, there's two or three 1.5' x 1.5' cuts in the ceiling
where I could only assume pipes used to run.

The cuts have since been covered on top with particle board.
The basement ceiling beams, which are large and old
are somewhat moist to the touch;
they have a very slight wet sponginess when pressed with my finger.
The particle board feels less spongy, but still has slight exterior wetness.


How should we approach this?
We believe the landlord, who just moved out of this apartment,
attempted to address the issue by pouring and vacuuming carpet cleaner,
but it was not enough.

We believe that if we treat the carpet,
it may not have a significant enough effect,
and worse, it will recur after a relatively small amount of time.

Thus, is it fair to request that the carpeting be completely replaced,
and that the flooring be somehow definitively insulated
against further contact with any sources of moisture?

Most importantly, in case the landlord is unsure of how to accomplish this,
what is the recommended approach to relieving such a home improvement issue?

The landlords are very nice and competent;
however, they have stated that they are from the West (US)
and are unfamiliar with basements as they have never had one before.

Would 1-2 layers of plastic lining just need to be applied
between the carpet padding and the hard flooring?
Would this be enough of a seal?

  • 1
    Why is the basement so damp? Jul 2, 2017 at 21:04
  • @ThreePhaseEel I don't know. All of the basement windows are constantly open to air it out, but we're the northeastern US (New England) — the outside air is temperate and therefore also moist. NOAA says we're averaging 60% relative humidity this week.
    – kando
    Jul 2, 2017 at 21:10
  • @ThreePhaseEel I would assume that keeping the windows closed and running a dehumidifier constantly would be the best method of clearing up moisture. As for leaks other than the windows letting moist air in; what are the typical sources of moisture in a basement that he should look for?
    – kando
    Jul 2, 2017 at 21:12
  • @ThreePhaseEel Alright, I checked the basement again. The foundation appears to be completely dirt in some areas, which explains the thin layer of dirt in other areas. I assume that it's a very old house. I'm sure that if the surrounding dirt becomes moist, that the dirt coming up through the floor becomes moist.
    – kando
    Jul 2, 2017 at 21:18
  • @ThreePhaseEel Would the recommendation be to patch the dirt somehow, or run a dehumidifier continually. If it was the latter, I looked at ConsumerSearch which recommended, among other things, a consumer-grade dehumidifier and a more industrial grade dehumidifier for basements (up to 2,200 sq. ft. loosely sealed). (Both require a pump to eschew the moisture out one of the windows.) The basement is roughly 25' x 40' (1000 sq. ft.).
    – kando
    Jul 2, 2017 at 21:44

1 Answer 1


The problems you describe are likely on the outside of the building. I'm willing to bet the landlord is unaware of this, or they are simply unwilling to fix it. This likely isn't fixable by you.

The moisture is coming through the concrete. Concrete is porous, so it will wick water from the surrounding soil naturally. To help prevent this process, basements are typically surrounded by a weeping tile. This is how the outside of the building basement should work

In new construction, this is corrugated pipe with a sleeve to minimize dirt, but in older buildings this was literally clay tile. So, what happens over time is this tile can break (it's ceramic), blocking the weepers. There's no way to find this out, except to excavate the outside wall and look at it. (image source)

My bet is

  1. The weepers are broken
  2. The wall has no waterproofing
  3. The ground does not slope away from the building (you can confirm this visually)

Repairing this is not cheap, obviously. It's not surprising that it was ignored if it was known about.

If the joists are spongy, it means they've absorbed a lot of water. I'm surprised it hasn't attracted termites yet. This could be making the apartment structurally unsound if it has been an ongoing problem. Even if there are no termites, the wood may begin to rot.

The only thing you can try yourself is a dehumidifier. But if the room is humid enough to wet the floors and joists, a dehumidifier will likely be overwhelmed very quickly (you will have to empty the collected water frequently). The owner should call in a foundation waterproofing company to excavate the basement walls, water proof them, install new weeping tiles, and slope the ground away from the structure.

  • Alright, thank you. How much would an excavation and repair approximately cost? If there is no desire to excavate, then what would the alternative be? If the carpet and padding is replaced in our room, how do we prevent regrowth? Is there a specific material to prevent that by lining between the carpet and the wet flooring? If we buy dehumidifiers, do we buy multiple consumer-grade dehumidifiers ~(2-3x $300)? An industrial grade dehumidifier ~($1400)? How should air be brought to the dehumidifier? Fans? Would you recommend a pump to jet the dehumidifier water outside?
    – kando
    Jul 3, 2017 at 0:24
  • (Also, I understand that it's tough to gauge costs, but could you ballpark it? $1000, $5000, $10000, $25000, $50000, ...)
    – kando
    Jul 3, 2017 at 0:32
  • 1
    I have no idea on costs. It depends a ton on the size of the building (longer walls = more money). There's no alternative to excavation that I've heard of. Perhaps a plumber could dig a hole and scope the tile, but with the moisture you're describing, the walls need waterproofing. Replacing carpet without solving the moisture will put you in the same boat. You may need mold remediation at this point. I don't know that a dehumidifier can fix this. I suggest it as a stop-go measure only.
    – Machavity
    Jul 3, 2017 at 0:37
  • Alright, thanks. I appreciate all of your insight, and I will relay it to the caretakers and allow them to make the calls.
    – kando
    Jul 3, 2017 at 3:21

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