How to address stagnant/stale air in basement

pete6032

Diamond Member
Dec 3, 2010
7,268
2,843
136
I live in a 1950s home. Basement was originally unfinished with cinder block walls and poured concrete. Previous owner finished the basement and put in drain tile system with sump pump, drywall, carpet, ceiling, etc. The basement is pretty good size, maybe 750 SF of livable area. The problem I have is that the air in the basement always smells stale/stagnant. I had a big family gathering down there and it got very stuffy very quickly. The only windows in the basement are cinder block hopper windows maybe 12x24 and they do not open. Is there some way I could install a ventilation fan somewhere to get fresh air down there? Either from outside or the first floor? Problem with outside is that it gets stupid cold during the winter, down to below zero at night, so not sure how feasible it is to have a fan pumping in freezing air. I had the basement tested for Radon and it came back at 4.0, which is borderline to install a mitigation system. Would a radon system help get clean air into the basement? Any thoughts?
 

Greenman

Lifer
Oct 15, 1999
19,853
4,716
136
A couple of small fans between the basement and the room above it would solve the problem.
 
Feb 4, 2009
34,191
15,361
136
Radon is a problem in my area and remediation systems are exactly what @Greenman said except the vent to to roof. Stuff is pretty affordable and non intrusive. If that’s what you need.
 

pete6032

Diamond Member
Dec 3, 2010
7,268
2,843
136
Radon is a problem in my area and remediation systems are exactly what @Greenman said except the vent to to roof. Stuff is pretty affordable and non intrusive. If that’s what you need.
I am not terribly worried about radon at the moment since the tests were at or below epa threshold and no one lives down there. Long term I will install a mitigation system but was just curious if that would have any secondary impact on making their air down there less stale.
 
  • Like
Reactions: Fanatical Meat

Red Squirrel

No Lifer
May 24, 2003
66,375
11,580
126
Could look at installing a HRV unit. It will basically exhaust indoor air and bring in fresh outside air but run it through a heat exchanger so you don't lose the heat in the process.
 

mindless1

Diamond Member
Aug 11, 2001
7,905
1,400
126
Yes you can install a vent fan, but first how is the drainage from the home? Does it have downspouts and sufficient length extensions to get rain water far enough away from the foundation, if in an area where you get a fair amount of rain? Is the ground graded away from the home so that rain runs away rather than towards the foundation? If not, those are a couple things to consider since you already have a sump pump.

Does the cinder block have sealant applied and is it in good condition? If not, on finished areas (you mentioned drywall) it's going to be a chore but it ought to be well sealed.

My point is you are probably dealing with high humidity and short of using a dehumidifier, or refreshing the air, the way to deal with that is limit water vapor intrusion.

Does the sump pump have a sealed cover on it? You might even be able to seal the existing cover with a patch panel around the pipe and a bead of caulking around everything, then when it comes time to service the pump, simply use a knife to cut the bead (you're only trying to seal at the top edges, not get so much caulking down into it that it is destructive trying to remove it later). That may lower radon a little as well.

I'm less a fan of bringing in outdoor air if it gets humid in your region, but if you have gatherings of people down there, it will be more comfortable to exchange the air either indoors or out.
 
Last edited:

pete6032

Diamond Member
Dec 3, 2010
7,268
2,843
136
Yes you can install a vent fan, but first how is the drainage from the home? Does it have downspouts and sufficient lenght extensions to get rain water far enough away from the foundation, if in an area where you get a fair amount of rain? Is the ground graded away from the home so that rain runs away rather than towards the foundation? If not, those are a couple things to consider since you already have a sump pump.

Does the cinder block have sealant applied and is it in good condition? If not, on finished areas (you mentioned drywall) it's going to be a chore but it ought to be well sealed.

My point is you are probably dealing with high humidity and short of using a dehumidifier, or refreshing the air, the way to deal with that is limit water vapor intrusion.

Does the sump pump have a sealed cover on it? You might even be able to seal the existing cover with a patch panel around the pipe and a bead of caulking around everything, then when it comes time to service the pump, simply use a knife to cut the bead (you're only trying to seal at the top edges, not get so much caulking down into it that it is destructive trying to remove it later). That may lower radon a little as well.

I'm less a fan of bringing in outdoor air if it gets humid in your region, but if you have gatherings of people down there, it will be more comfortable to exchange the air either indoors or out.
Thanks. Drainage is an issue for sure. My yard is very small and very level. Buried downspouts are extended out to the property line in the back but previous owner did not put large enough pipes in and they do back up occasionally. I will be tearing them out and doing it with proper 4" PVC this summer. I will take a look at the sump and make sure it's sealed properly. The sump runs a ton, especially right now dealing with all the snow melt. The soil is very wet.
 

Gardener

Senior member
Nov 22, 1999
748
526
136
Replacing one of the windows with one that opens will make it livable during fair weather, it doesn't take much of an opening to cycle the air. When you have the window closed, run a dehumidifier. Once you draw down the ambient moisture levels it will smell and feel better.
 
Nov 17, 2019
10,010
5,939
136
Replace ALL the windows so they open. In at least one, install a fan. Rig a way to block it off in cold seasons. Then rig another fan upstairs somewhere to pull air through. Just having the windows open with the stairway door open to allow passive ventilation will work wonders.
 

Red Squirrel

No Lifer
May 24, 2003
66,375
11,580
126
Water intrusion is the issue that I'd focus on. If it's that humid down there then clearly water is getting in somehow. When I bought my house I found the same, ended up realizing I had to redo the weeping tiles. Around 17 grand. But with inflation now days that job would probably cost way more, so I'm glad I did it then. Now my basement is fully insulated and sealed and it's very dry and warm down there. It's actually better than rest of house.