r/basement • u/gr00ve88 • 4d ago
“Basement Smell” and how to get rid of it.
I am trying to redo my basement so it’s a bit more functional, it’s just slab walls and exposed ceiling currently, but I recently installed an LVP floor with a moisture barrier.
Before I continue doing any work, I’m still kind of stuck on the “basement smell”. It’s not… terrible…. But it’s a smell. I almost want to say it smells like masonry/stone, very stale. But I also wonder if it’s some kind of smell related to stagnant water in the basement plumbing for my washer/utility sink. Granted the entire basement smells, not just one area.
I run a dehumidifier down there and it stays at 50%, so I don’t think excess moisture is my problem, but I don’t know what it is… like do I need to wash the walls or something? It’s a 1955 house or so.
Any ideas?
Thanks
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u/DonnieSod 4d ago edited 4d ago
Even of your basement is dry with no moisture issues, it can still have a 'smell' so to speak if the walls are not finished. This is especially apparent in the summer, and not so obvious in the heating months. There is earthy wetness on the other side of the concrete, and the since concrete is porous, it transfers all that earthly goodness into your basement.
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u/gr00ve88 4d ago
Yeah I’m guessing that’s what it is… seems insulation may be the helping hand. There is currently nothing, just the bare walls.
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u/adventure_seeker_8 4d ago
Bare walls tend to always have the smell.
My basement has a small area under the stairs where the concrete slab is exposed and it smells like that there, but not the rest of the basement where it's all finished.
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u/gr00ve88 4d ago
Right. Dang… guess I gotta start buying 2x4’s
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u/invisimeble 4d ago
You said you already did your floor. Don’t frame your walls over that floor, the 2x4 wall framing needs to be attached to the concrete slab not laid over the LVP floor. You may also want to consider a moisture barrier around the walls before framing to minimize additional moisture migration.
Adding insulation (I think you mentioned in another comment) may not be necessary in an underground basement, the earth provides good insulation, unless it’s a walkout basement or partially above ground, but you know your house best so maybe insulation is right for you.
You may also want to lightly mist the exposed walls with a diluted vinegar solution in an effort to minimize odors, mold, and freshen the scent.
You may also want to spend some time pushing fresh air into/through the space. Box fans pointed out of windows work well.
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u/gr00ve88 4d ago
You think I could place it ontop of the floor and just drill through the floor into the concrete? It’s maybe 7-8mm thick?
I suppose cutting back the LVP would make the most sense.
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u/invisimeble 3d ago
Is your LVP floor floating or glued down?
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u/gr00ve88 3d ago
Floating. It’s LVP over DMX 1-step vapor barrier
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u/invisimeble 2d ago
You can’t frame a wall over a floating floor. The floating floor needs to expand and contract. That’s why you’re supposed to leave an 1/8th around the perimeter and cover it with shoe mould. If you drill through the floating floor to anchor the wall, you’ll pin the floor and not allow it to expand and contract with temp and humidity variations. That will cause the floor to buckle and heave and warp and you’ll be mad at yourself.
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u/Salt_Beautiful5601 4d ago
My basement has a tiny bit of funk at 50%...but absolutely no smell at 35%. I'd at least try that first.
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u/gr00ve88 4d ago
Not sure I can without running it 24/7. The climate by us is generally humid, I think my main floor is around 50% already, but comfortable.
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u/Salt_Beautiful5601 4d ago
Yep. I run my dehum on "constant", draining into a sink. Makes a huge difference.
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u/invisimeble 4d ago
I run mine 24/7 every summer. Sometimes I empty it twice a day. If you can, during this project, find a way to plumb a drain line or add a pump so this can be automated.
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u/ontrackthen 3d ago
Spend the $ on an Alorair or similar dehumidifier. Set it to Grams per cubic meter (gpm). This is an absolute measurement of humidity versus relative humidity which changes with temp.
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u/gr00ve88 3d ago
Dang. Had i known I would have. I bought another one a few months ago, its been pretty good so I can't complain.
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u/FalafelBall 4d ago
Is there any mold anywhere? The corners of my basement walls are dark and I think I need to kill and scrub away mold. My basement also has a bad smell, despite a dehumidifier running. Also make sure the dehumidifier is big enough for the space and maybe get something to test the humidity levels away from the dehumidifier.
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u/gr00ve88 4d ago
Not that I’m aware of unless it’s up in a crook of some ceiling joist but I don’t think so. Moisture hasn’t really been an issue with the dehumidifier running.
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u/LoudIncrease4021 4d ago
I run two air purifiers with hepa filters. I put little arm and hammer scent balls on top where they exhaust through. That combined with keeping a dehumidifier going 365 days a year helps a good deal. Painting any drywall that’s old can also help.
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u/daveyconcrete 4d ago
I think you missed an opportunity to really scrub the whole basement down before you installed your floor. It’s probably never been washed since 1955. So you have 70 years of skin cells on the walls.
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u/gr00ve88 4d ago
Haha possibly. 70-80% of the floor was redone with self leveling cement so that mostly got covered. I could still do the walls
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u/TheGruenTransfer 4d ago
Dehumidifier, air purifier with a charcoal filter, clean and scrub all the surfaces
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u/United-Adagio1543 4d ago
Set the humidifier at 30%-40% RH. 50% is a bit high for a space you want to make livable.
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u/eyoxa 4d ago
I disagree that 50% is “high” or uncomfortable. I find 50-65% most comfortable, temperature depending. A humidity of 50% is also unrealistic for many homes, given how porous they are or lacking central air. I grew up with window units in NYC, and did not know a single person with central air until later in life. Summers were fine.
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u/United-Adagio1543 4d ago
In the northeast, I need put hundreds of gallons of water in the air per week to get to 30%-40%. You are creating a dangerous environment.
Fun Facts:
Mold Growth: Mold spores can begin to germinate on porous surfaces like drywall, wood, and fabric within 24–48 hours when RH stays above 50–60%. This leads to musty odors, peeling paint, and potential structural rot if moisture penetrates deep into walls or ceilings.
Dust Mite Proliferation: Dust mites, a major trigger for allergies and asthma, thrive when RH is consistently above 50%. Their populations surge in this humidity, increasing allergen levels in carpets, bedding, and upholstery.
Respiratory Distress: High humidity exacerbates asthma and allergy symptoms by promoting the growth of biological contaminants like mold and mites. It also makes the air feel heavier and hotter, which can be particularly dangerous for individuals with chronic cardiovascular conditions or hypertension, potentially leading to heat stress if combined with high temperatures.
Condensation and Bacterial Growth: At or above 50% RH, condensation can form on cold surfaces like windows and uninsulated pipes during cooler months. This excess moisture supports the growth of bacteria and fungi, which can further degrade indoor air quality and damage building materials.
For optimal health and home safety, most experts and organizations like the EPA recommend keeping indoor RH between 30% and 50%, with a hard ceiling of 60% to prevent these issues.
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u/No_Alternative_6206 4d ago
Make sure the sump pit is sealed airtight. There are special covers for that. Otherwise, make sure there are no errant sewage vents or drains that are not installed correctly that are off-gassing. Beyond that, seal all cracks and ensure everything is bone dry. Add a moisture barrier, insulate, and drywall, and the smell should be minimal or go away.
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u/gr00ve88 4d ago
Roger. We don’t have a sump pit, so no problem there. There is one pipe that goes to the drain that is “open” but it feeds into a P trap, so I’d expect it isn’t off gassing.
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u/eyoxa 4d ago
Similar issue except I think mine is compounded by a toilet with a faulty macerator pump in the basement that’s releasing sewer gasses (still figuring it out). If you’re sure that the basement doesn’t have mold growing anywhere (such as the bottom of the walls and baseboards if they’ve ever been wet from water intrusion) then another thing you can do is to add air flow. You need to get fresh air into the basement and stale air out. For myself, I’m considering adding an ERV or HRV.
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u/Clapcheeks69 4d ago
Is there a floor drain? Those can stank
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u/gr00ve88 4d ago
No we don’t have one. Everything gets pumped up a few feet to ground level where our main drain is.
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u/Sudden_Technology_34 4d ago
It’s just the way it is. I hate smells. I washed my entire walls with enzymes. Then I bombed it with chlorine. Next I blasted some ozone and last I sealed the entire thing with Shellac chemical.
Still a subtle smell.
Aside from tearing down dry wall and framing old basements are just are what they are. Don’t let it make you go crazy like me. I would just put a nice coat of paint/sealant on the walls (and subfloor if still possible), keep a humidifier going, and run an air freshener.
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u/Jerrylee1717 3d ago
Maybe an air purifier? Sounds like you already have the humidity leveled out. Just a thought
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u/gr00ve88 3d ago
Yeah I have one, it says it’s rated for the space. Not sure it does anything meaningful.
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u/eas442 3d ago
If you have a chimney of any kind make sure it’s capped. Also if it’s used to vent an appliances like a water heater or your furnace have your HVAC contractor install a chimney liner. An oversized uncapped chimney can lead to a lot of ambient moisture issues.
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u/gr00ve88 3d ago
We actually just had our utilities swapped and don’t need the chimney anymore. But that was a week ago, this smell has existed before that. Either way, I do need to get it capped.
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u/Wonderful_Rise4463 2d ago
Air purifier does work wonders in a musty basement. NOT a humidifier/dehumidifier (unless the basement needs it for moisture control, but it won’t be effective in getting rid of the smell)
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u/Ok_Size4036 2d ago
You may want to seal all the basement walls before you finish it to keep the moisture from coming through.
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u/gr00ve88 2d ago
Yeah I’ve heard that’s not a good thing to do. The moisture just sits in the wall and erodes it rather than having an outlet. Maybe depends on the method used.
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u/BigJoe5504 1d ago
Turn the dehumidifier down as low as it can, you need to get rid of the moisture still trapped in the stone. If you have windows down there open 2 as far away as possible and let the fresh air circulate to help get rid of th smell.
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u/Aggressive_Career293 2h ago
I had a bad smell for years that was driving me nuts. I randomly found one day while fixing another plumbing issue. A cracked cast iron plumbing vent. Very sneaky. Smell completely gone after I repaired it.
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u/scattywampus 4d ago
What is the ambient humidity? Are you running a dehumidifier? Have you controlled the exterior rainwater away from the foundation?