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Small Cabin Forum / Cabin Construction / Condensation on the cabin walls
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WILL1E
Moderator
# Posted: 20 Nov 2022 12:35
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It was a bit chilly this weekend, highs in low teens and single digit nights with a decent wind as well. Inside the cabin we kept it between 68-74 with the pellet stove and the ceiling fan on medium. This morning however as we were packing up and cleaning I noticed anything that was sitting on the floor or against the wall was wet or iced. So places like behind the couch that’s against a wall, plastic totes stored under the bed, dog bed laying on floor ,etc.
my assumption is that this is due to the cabin being elevated and my floor not being insulated and the warm air inside not being able to circulate and move through those areas. Is that right?

If so, how do I avoid this? I mean I can move stuff away from the walls but I can’t defy gravity!!

Lastly, how should I handle the moist spots on the drywall? Hair dryer? Space heater that will blow on it?
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Steve_S
Member
# Posted: 20 Nov 2022 13:24
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You can dehumidify with "DRY HEAT" such as Electric. You may also consider a dehumidifier but they suck energy as bad as an electric heater. Once that moisture is IN the walls you'll have other problems appearing (or not) if black mold sets into the walls or saturates the drywall then it is a health hazard that is very hard to deal with.

The BEST thing to do is to insulate your floor, and have a Heat Recovering Air Exchanger (regardless), and do use an exhaust fan in the kitchen when cooking and in the bathroom when showering etc to prevent introducing more moisture.

Now if your walls are actually cold and you did insulate that may be a sign of other issues within the walls. Anything from critters having gotten in and nesting within (listen carefully for rodents), shifting/sagging insulation and such. I have ripped walls open only to discover large mouse habitats in some houses where they chewed holes into the sheathing between the siding, or entered from the roof cavity.

A buddies 40 year old house was infested and appeared with symptoms of cold exterior walls and condensation on them, we cut a few exploratory holes and mice fell out of the fiberglass... All teh drywall had to be removed along with the remnants of insulation and redone, we found several entry points in the sheathing and from the roof. Lucky for him, we could DIY it otherwise the cost would have been insane.

Tim_Ohio
Member
# Posted: 20 Nov 2022 15:36 - Edited by: Tim_Ohio
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So, you were there for only the weekend and the cabin was ice cold before you fired up the heat source….get my point. It takes a long continuous heating process to heat an interior, completely. Guess what you add when you start heating and occupying a cabin from ground zero….water vapor, which has nowhere to go because there is an excellent vapor barrier protecting the insulation. Stay for a week and see what happens when you continue to bring all hard surfaces up to temp over a longer period of time.

ICC
Member
# Posted: 20 Nov 2022 23:03 - Edited by: ICC
Reply 


The elevated and uninsulated floor is much of the problem, IMO. Insulating it will help a lot.

Heating the interior with a wood burning stove, including a pellet stove, should not raise the humidity. The relative humidity will fall as warm air can hold more moisture. It is quite possible to see some condensation on any area that remains cold because of poor insulation or air leaks.

FWIW, my cabin has R25 in the floor joist bays as well as code or better in walls snd ceiling. We have ceramic tile over cement fiber backer board on top of Advantec sub floor throughout the cabin. Heat is primarily a wood stove once winter sets in. It never takes more than 24 hours to get even the tile floor to be warm enough to use the cozy adjective. If the insulation is sufficient and well fitted and the structure has no air leaks that should be easy enough to achieve.

I know this next comment will not help the current situation, but it may help someone in the future. Drywall should never sit on the flooring. There should be a 3/8 to 1/2 inch space under the lower drywall edge. We use a foot jack to lift and hold the panels off the floor while it is screwed into place.

DaveBell
Moderator
# Posted: 21 Nov 2022 00:00
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Willie, did you create humidity inside by cooking and shower/bath?

FishHog
Member
# Posted: 21 Nov 2022 07:35
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Quoting: DaveBell
Willie, did you create humidity inside by cooking and shower/bath?


and just breathing. We give off a lot of humidity.

I agree with the points above, but its tough to avoid completely on weekend trips showing up to a cold place. I'm sure it would be better if you were there longer. Just make sure you leave good ventilation when you leave and give some thought to insulating the floor next summer.

WILL1E
Moderator
# Posted: 21 Nov 2022 08:15
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We were there only for the weekend, but it was 4 of us and we spent most of the time in the cabin, so a lot of breathing inside. Cabin was 22deg when we got there and was up to 68 or better in about 2 hours.

We don’t have a shower inside or running water for that matter. Only cooking we did was a couple short warm ups of food in microwave.

I agree the floor needs to be insulated, for multiple reasons, it was just at the bottom of the list of must dos for this year.

I plan to relocate everything away from exterior walls when I go up again. I’ll have to check what my weather station says for humidity level, I think it shows it for inside and outside.

Aklogcabin
Member
# Posted: 21 Nov 2022 10:01
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New homes can contain quite a bit of extra moisture from latex paint n such. Or if exposed to the weather during construction. That can take a bit to dry out. Hopefully that's the only issue. Good luck, you have a nice looking cabin

Brettny
Member
# Posted: 21 Nov 2022 13:40 - Edited by: Brettny
Reply 


That is quite a bit of moisture. I would start with a few box fans to blow the hot air around some. I would also insulate the floor.

More than likely theres an air leak there also. Mold grows behind drywall prety darn quick too.

BRADISH
Member
# Posted: 23 Nov 2022 16:53
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I had a similar issue in my cabin I noticed the first weekend I stayed in it. Not as bad, but noticeable.

I ended up bringing a dehumidifier up with me the next weekend and ran it as often as I could (It would trip the generator with tools running). I pulled out about 2 gallons that weekend.

I intend to bring it up with me probably every other weekend this first winter, as I think there is still a lot of moisture in the materials as I too have recently completed construction.

I also left a large container of "damp-rid" to passively gather moisture while I'm not there. I think getting over the hump of the first winter after you've closed it all in will be the big thing. After that it should get easier.

WILL1E
Moderator
# Posted: 14 Dec 2022 14:10 - Edited by: WILL1E
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If I were to put 1.5" or 2" (not sure if going up to 2" is worth the extra 25% in cost) pink polystyrene foam board between the floor joist, do you think that would solve the cold floor problem? Since the cabin is 16x32, I can get away with a single seam in each joist bay. When it warms up in spring i would spray foam that seam as well as the corners between the foam and the floor joist.

Would the critters go after that stuff.

Nate R
Member
# Posted: 14 Dec 2022 15:38
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Not sure if that would solve it enough if the joists are still thermal bridging the cold through, hard to say for sure.

-Nate

rpe
Member
# Posted: 14 Dec 2022 16:41
Reply 


My buddy jammed in foam board from underneath like that. He noticed little improvement in floor temps. The mice and red squirrels loved it though, wiggling their way in above the foam. Sounded like a race track underneath with them scampering back and forth! I wouldn't bother until you can seal it up well, preferably with a continuous layer of spray foam.

Brettny
Member
# Posted: 15 Dec 2022 08:11
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Quoting: rpe

My buddy jammed in foam board from underneath like that. He noticed little improvement in floor temps. The mice and red squirrels loved it though, wiggling their way in above the foam. Sounded like a race track underneath with them scampering back and forth

This is why you need to push that foam board right up to the bottom of the sub floor along with useing caned foam around all the edges.

FishHog
Member
# Posted: 15 Dec 2022 08:17
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Quoting: Brettny
This is why you need to push that foam board right up to the bottom of the sub floor along with useing caned foam around all the edges.


agreed, I did just this at my old place and it made a noticeable difference.

rpe
Member
# Posted: 15 Dec 2022 08:32
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Quoting: Brettny
This is why you need to push that foam board right up to the bottom of the sub floor along with useing caned foam around all the edges.

Definitely. Without an air seal along the edges, that insulation value will be compromised for sure. That, along with the rodent issues I mentioned. But Will1e stated he'd stick foam panels in now, and spray foam the joints in the spring. By then it might be a critter condo.

DaveBell
Moderator
# Posted: 15 Dec 2022 09:37
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https://www.cabinlife.com/articles/does-your-woodstove-cause-condensation-inside-the- cabin

curious
Member
# Posted: 15 Dec 2022 10:16
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Any moisture-related problems with any link to wood stove operation can be eliminated with a fresh air inlet direct to the stove.

Brettny
Member
# Posted: 15 Dec 2022 11:12
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It seams like that cabinlife.com article is about warming up a cold cabin. Any time warm air hits cold objects your going to get condensation weather it's under a couch or at the bottom of your metal roof. So saying it's a wood stove related issue isnt correct. In fact the wood stove may help dry it out due to them making interior air very dry. Moving the air will help dry the moisture and warm up the objects.

WILL1E
Moderator
# Posted: 15 Dec 2022 13:31
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Quoting: Brettny
This is why you need to push that foam board right up to the bottom of the sub floor along with useing caned foam around all the edges.

Yes, this is what i was trying to imply.

WILL1E
Moderator
# Posted: 15 Dec 2022 13:32
Reply 


Quoting: curious
Any moisture-related problems with any link to wood stove operation can be eliminated with a fresh air inlet direct to the stove.

I have that with my pellet stove.

NorthRick
Member
# Posted: 15 Dec 2022 16:35 - Edited by: NorthRick
Reply 


Quoting: curious
Any moisture-related problems with any link to wood stove operation can be eliminated with a fresh air inlet direct to the stove.


Actually no. If the wood stove is getting it's air from the room, then outside air has to come in to the room from where ever (cracks in the walls, floors, around doors etc.) Cold air can't hold as much water vapor than warm air. When this cold air comes into the cabin and is heated, for lack of a better term, it "dries out."

This warm "dry" air will pull moisture off of surfaces and then gets sucked into the wood stove and goes out the flue taking the moisture with it. A combustion air duct into the wood stove is more efficient heat-wise, and can make a cabin more comfortable because you reduce drafts, but it doesn't have much effect on the relative humidity in the cabin.

I agree with the other posters, insulate your floor. Over time, the moisture level in your relatively new cabin should decrease and the problem should go away.

We don't see issues like this until temps are subzero F.

travellerw
Member
# Posted: 15 Dec 2022 18:15
Reply 


Quoting: NorthRick
This warm "dry" air will pull moisture off of surfaces and then gets sucked into the wood stove and goes out the flue taking the moisture with it.


I agree with this %100. Our cabin doesn't have a cold air intake and the wood stove will dry it out so much that you have to have a pot of water on the stove at all times. If you don't, the air will get so dry that it causes nose bleeds.

Our last trip it was about -10C and we didn't even get condensation on the windows since it was so dry. Even with a pot of water on the stove.

Brettny
Member
# Posted: 15 Dec 2022 18:43
Reply 


I have owned the same house and the same stove. For a few years it didnt have an outside air kit and now it does. I can tell you that this makes very little difference in the humidity. I can tell you that having an outside air kit made my house warmer and I burn less wood. I would never own a stove again with out one.

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