Damp smell in Portland OR basement

18 Replies | Portland, Oregon

Have owned rental for many years and newer tenant complains of moist smell and imagines mold situation in basement. It has a rather dank smell but no visible moisture or mold. Tenant wants a dehumidifier.

I would check your gutters ASAP and then the furnace condensate pump.   It’s been rainy and cold so those are my two guesses.

Gutters to sure that everything regarding rain water is draining properly.  And the condensate to make sure it’s not plugged (this only effects high efficiency furnaces, 80% do not have condensates).

I  would provide a dehumidifier, but also make sure that I solve the underlying problem as soon as possible.  

Good luck!

In our basement we run a fan. Just a typical 20" box fan. It runs 24/7/365. This fan has run for the 19 years we've been in this house and it keeps any mold and mildew from forming. Keep the air moving and you won't get mold.

I had  the luxury of pumping a basement that for years had been neglected to find a crack in a 3" ceramic pipe. The outcome were a roach infestation that took 2wks of bombing as well a pipe replacement, added 3/4ton of dirt/sand, and ventilation. Good luck.

Thanks all for the responses. I am going over today and buy a hygrometer to see the humidity level. 

@Chris Shepard  The furnace is an older (25 yrs) gas and the gutters have been redone extending away from the house.

@John Teachout that is interesting do you leave a window open? It can freeze in Portland so that could be tough.

@Jeff S. I think all the ideas here are great. To expand on the fan idea...We have a four plex on a slab in farmland so the ground around is really wet. In heavy rains they just tend to feel a little damp. No water intrusion just a general damp feeling (we've done the gutters and all that). We installed fans that have a humidity sensor and run when the humidity reaches a certain level. They look like a bathroom exit fan you would have in the ceiling of a bathroom. Might be an inexpensive solution if you have an easy place to vent it? That rain early last week was insane so the ground water just might be higher than normal?

No for the fan, we don't leave windows open. The fan just sits on the floor. We've found it doesn't really matter where in the basement area it's located. Just that it's important to keep air moving down there.

@Jeff S. If the house is old, then this is a common problem. The foundations didn't have any dampproofing to stop any moisture vapors from entering.  I have an old rental and it smells old and smells a little, some is from the old wood (unfinished basement).    Running a humidifier will help solve the problem.  If you decide to get one,  attach a hose to the tank and run it to the floor drain.  Then run the unit 24 hrs or put it on a timer for like 15 hrs or so.  Air movement is also key to keep mold from forming.   The other approach you can take, tell the tenant you to provide one if they want.  If you add the humidifier, add it to the lease to what is owner furnished.  When it walks away you can fine them for it. 

@Jeff S.

Hey Jeff,

The reason I recommend checking the gutters is because i thought you said this is a new thing that just started very recently. (Last 2 weeks).

Just because the gutters have been redone, doesn’t mean that they don’t get clogged. If they get clogged then it doesn’t matter where they are routed to, the water just comes straight down the side of the house and into the basement.

I had a massive flood at one of my properties during a crazy rainstorm because the gutters were clogged.

Good luck!

Thanks @Lisa Thoele an exhaust fan sounds like a good idea. Sounds like will need the dehumidifier @Jim Adrian @Ned Carey  Our houses on this side of river in Portland are generally built in 1910-1920. The tenants had said something about the upstairs smelling moldy so had a mod test done and there was less in house than outside @Cory Carlson . May have done in basement. Cost $300. No floordrain @James Galla . Will be having those gutters cleaned @Chris Shepard . Had 3 houses done yesterday.

Ok gutter cleaning ordered> Hygrometer says 90%+ humidity and 58% outside.

What is a good dehumidifier?

@Jeff S. Without a floor drain the dehumidifier will shut off when bucket is full of water. This could be every 12 -18 hrs.  If the tenant never empties it then the problem will never be solved.