Humid Cellar
Hello! So approaching the 1 year mark of owning my little condo with cellar access.
Recap: Around August 2020 I removed 90% of the drywall in the cellar. I discovered that it was almost all moldy (seriously, in some cases moldy drywall was put on top of slightly less moldy drywall). The removed drywall was not replaced.
Now after living here for about a year I am realizing it is very hot and humid down there. I don’t have a meter yet but we are running 2 dehumidifiers (they are 35-50 pint) (one has been hooked up to a pump — thanks @bobjbkln! it works great!)
Is this just how cellars are? Are there different things I can do to help move air around? I have been keeping an eye on the cellar since taking off the drywall and there aren’t any leaks… but the brick and stone are probably taking in the moisture of the ground?
I plan on limewashing the brick and stone foundation soon.
Any theories?
nathanjoe755
in General Discussion 3 years and 10 months ago
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brownstone89 | 3 years and 9 months ago
If u get real lucky u may talk to enuf contractors that u find one able to give u an intelligent solution and u could have them give u a price and a liklihood of success.
JohnHancock | 3 years and 10 months ago
I think you should inform them ASAP since this may be a problem caused by something that’s not directly caused by you but may be a building problem that the board should address rather than just you
nathanjoe755 | 3 years and 10 months ago
oh interesting thanks for the warning! Whatever I do I need to inform the condo board… and I still haven’t told them… so no solutions will be happening right away.
dorkofwindsor | 3 years and 10 months ago
You have to be careful the humidex does not create negative pressure in the building. It is another source of exhaust in the basement with no makeup air so humid air could be sucked in from upper floor window cracks etc. In general negative pressure around combustion appliance exhaust makes me personally uneasy as far as carbon monoxide venting goes.
nathanjoe755 | 3 years and 10 months ago
Hi Urbandad if you had more to add, I would love to read it.
Hardcharger this is great info! I really appreciate your lived experience and solution. Defiantly will look into a Humidex!
Hardcharger | 3 years and 10 months ago
HUMIDEX. There used to be ads on am radio. I kept a cellar dry in my old co-op. It really is about air/exchange and venting. The unit grabs the air from floor level and exhausts it out like the building like a dryer vent. Fresh dry air enters the cellar by way of the stairway. If you have a closed door, you need to cut a vent or maybe one in your floor. It really did work and I learned a bit that also helped me get the most of my air conditioners. Apparently Home Depot now carries it, but not in
Brooklyn….. much cheaper than my contractor got it. https://www.homedepot.com/p/Humidex-Smart-Whole-House-Basement-Energy-Efficient-Digital-Ventilation-System-Dehumidifier-for-2400-sq-ft-HCS-BMH-HDEX/310468757 I found the dehumidifiers generate a lot of heat. The Humidex worked best when I raised every thing up to shelves with legs . No boxes , bins on floor.
cate | 3 years and 10 months ago
Your comment got cut off, Urbandad. Would love to hear the rest.
hkapstein | 3 years and 10 months ago
Late to the party, but cellars are cool due to the relatively consistent ground temperature below the frost line. Hot humid weather in the summer results in condensation and water accumulation in the cellar. In general this issues will not be complained about to architects and engineers before sign-off so ymmv with them. Passive house architects may be more aware of such issues. Insulation in the walls particularly under the slab can have affect moisture and humidity significantly, and the a
cate | 3 years and 10 months ago
Yes please do, would love to hear what you find. Good luck with everything.
nathanjoe755 | 3 years and 10 months ago
This was all super helpful thanks! I will report back once I know more if only to help someone further down the line.
cate | 3 years and 10 months ago
Maybe speak to the other tenants/the board first and/or read the minutes first before consulting an engineer? Anything going on in your part of the cellar would probably be happening in the rest of the cellar and your part will affect the rest and vice versa. In fact the cellar can affect the entire building. And you certainly want to be sure everything is structurally sound (such as no broken pipes outside sending water into the cellar, which can destroy the footing — but it doesn’t sound like that’s an issue). I don’t know what limewashing is and I don’t know much about brick (our cellar walls are rubble). If the grout is falling apart, typically people recommend repointing (and in the case of our rubble walls, parging — not sure if that’s recommended for brick). Apparently it has to be done quite often, like every decade or so. I would think this would actually be the building’s responsibility, since this is structural. In my experience, yes, some dampness is to be expected, and I would never dream of putting drywall in a cellar for that reason. Supposedly you can m ake it dry by digging down outside and waterproofing the wall from the outside and also laying down a slab with a moisture barrier (and maybe other stuff) underneath, but needless to say it’s terribly expensive and not very practical, plus I’m not sure it really works 100 percent. In any case, I’d think getting some fresh air down through through a vent would be vital. As well as the dehumidifiers. And I’d never store anything down there (and if you do, make sure it’s raised off the ground with air circulating around it). Good luck.
dorkofwindsor | 3 years and 10 months ago
That channel may be a source of humidity if it is just a dirt bottom. Could be an interior drain tile though, can’t say for sure, but if so that isn’t a bad thing. The lime wash seems like a fine product to use on brick.
Guest User | 3 years and 10 months ago
http://www.pilloriassociates.com Spoke to him about my cellar though different issues.
nathanjoe755 | 3 years and 10 months ago
Thanks! This is helpful!
Yeah, I don’t have a row house.
The building I am in is divided into 4 quads. I have two exterior facing and two interior facing walls. It was built in the early 1900’s and renovated in the early 90’s.
The concrete is actually tiled over except for a 8 inch wide by maybe 3 inch deep channel around the perimeter of the exterior facing walls. The dark line is actually an access cover to the different pipes that service the building. There is also maybe 2-3 feet of space down there? I haven’t poked my head down there for too long because it gives me he willies.
I turned off one of the dehumidifiers and that did ramp down the heat quite a bit so thanks for that suggestion!
The boiler room is enclosed and is vented. But I will look for air tightness!
I will look into an ERV system… and also try and find an engineer who can give me some advice.
cate | 3 years and 10 months ago
An engineer might charge anywhere from $400 to $2,500 to come take a look — the higher number could include two site visits and a report. If you get a firm that is really good and gives you accurate and detailed information about the state and needs of the cellar, not just vague one size fits all platitudes, it is money well spent in my opinion.
dorkofwindsor | 3 years and 10 months ago
Yes, basically this is just how these basements are.
unclear what is going on with that floor, it could potentially be a similar mold problem. If there is a concrete slab I would highly recommend you leave it bare – I see something on top which will trap moisture and mold.
I would put my money on the heat you are feeling is from the dehumidifiers if there are no windows down there. Basements should be cooler in the summer but more humid. Having said that, if the doors to the basement / cellar are leaky from an air standpoint, it will suck in more hot humid outdoor air, which requires even more humidification, which in turn generates more heat. Humidifiers throw off serious heat by design – its how the dehumidification process works.
Some people may recommend an ERV (an ERV does some dehumidification), which will bring in somewhat tempered fresh air into the basement space. In the humid south newer builders use ERV’s to temper (and slightly dehumidify) and then also use dehumidifiers (which don’t have to work quite as hard). If you put an ERV on a timer say 10 minutes every hour your basement should seem fresh and the humidifiers may not have to work quite so hard, and it shouldn’t use much energy at all.
As far as a “boiler room” – if you do have a self enclosed, ventilated boiler room, check for air tightness so that heat and humidity is not making it through to your basement space. If there is no self enclosed boiler room that is another issue, but obviously the heat from the water heaters will add to the heat.
JohnHancock | 3 years and 10 months ago
Maybe OP doesn’t have such a setup and his cellar isn’t in a traditional row house but a different kind of building. OP can you elaborate?
RobertGMarvin
in General Discussion 3 years and 10 months ago
You might try simply leaving your front and back hatch covers open on a few hot sunny days.
nathanjoe755 | 3 years and 10 months ago
Does any one know what how much getting an architect or engineer to give me some recommendations would cost? Does any one know of someone and architect or engineer with knowledge with dealing with cellars?