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Small Cabin Forum / General Forum / Condensation
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paulz
Member
# Posted: 14 Jan 2021 12:41
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It's been cold (for here), wet and foggy for the last week. Yesterday it broke and was 10 degrees warmer. Got to my shop at the cabin, everything inside was wet, vehicles, tools..

My understanding is the warm air dumps it's water vapor on the cold surfaces, dew point and all that. I have some solar power there now but not enough to run electric heat, it's 2,500sf.. What else can I do, would a fan help? I'm leery about propane heat with gasoline and other chemicals inside.

Steve_S
Member
# Posted: 14 Jan 2021 13:09
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Propane unless vented will drop more moisture into the environment. It really is nasty for that.

Kerosene heater could work to heat things up and help dry it out somewhat. 2500 square feet though + ceiling height etc (think cubic feet) will take quite a bit. Thing is, you could heat up the building and then vent it for 15 minutes every 2 hours to evac the warm humidity but it is a tedious process.

Electric is not a solution, it will take a huge amount of juice to "dry out".

A fire in a woodstove / fireplace would certainly pull the moisture out but you don't have that for the shop I guess. This is likely the fastest & most efficient way to dry out a building though.

Damp is okay for a little while but if too long it will cause mold and that is never good. Moving air always helps keep damp a bit controlled but it has to go somewhere.

paulz
Member
# Posted: 14 Jan 2021 13:16
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Thanks Steve. I'd mostly like to prevent it in the first place so my tools and vehicles don't rust up. I could install a spare wood stove I have and vent it out the building, the problem is when to know I will be facing this situation. For the last couple months I have been working in the shop, in the cold, and not had any condensation.

Peewee86
Member
# Posted: 14 Jan 2021 13:20
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Unvented propane heat will add more humidity inside your place. Water vapor is released as a product of combustion. Your best bet would be an air exchanger. A passive air intake and a bath fan would help but that would not retain interior heat like a air exchange system would.

Brettny
Member
# Posted: 14 Jan 2021 14:05
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Was it cold inside and warm outside? Did you leave the door wide open to heat the place up?

toyota_mdt_tech
Member
# Posted: 14 Jan 2021 14:11
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Quoting: paulz
Got to my shop at the cabin, everything inside was wet, vehicles, tools..



I have a 12X16 toolshed at home and had this happen once too, I installed 2, 12"X12" gable vents at each end, problem solved.

Need air flow./movement. Just add vents and the problem goes away. Size the vents to the bldg.

snobdds
Member
# Posted: 14 Jan 2021 14:58
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I'm not understanding this. For condensation to happen, the interior has to be warmer than the outside for warm air to condense on the cold metal. If there is no heat and it's cold inside, there is nothing to condense.

toyota_mdt_tech
Member
# Posted: 14 Jan 2021 16:15 - Edited by: toyota_mdt_tech
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snobdds, I think you will get temp difference if it doesnt breath. Its what happened in my toolshed. Wasnt insulated, but after a cool evening, afternoon sun comes up and warms it all up, cold items inside all condensed with beads of sweat. Metal items were wet. I think the vents make temps the same, but the moving of air kept the humidity down.

paulz
Member
# Posted: 14 Jan 2021 16:34
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Quoting: Brettny

Was it cold inside and warm outside? Did you leave the door wide open to heat the place up


When I got here yesterday morning I opened one of the 8x8 doors, threw some stuff inside, left the door open and continued on to the cabin. Farted around there for a couple hours then went back down in the afternoon and noticed it, water droplets even on tools. So I don't know if it had been that way or happened after the door was open for a few hours.

The building is by no means air tight, still unfinished with gaps and openings here and there, but no leaks. It's up against a hillside and cut off from any wind, no real air circulation.

I worked about 3 hours there yesterday, left the door open all night, everything is dry today.

I could hook up a fan to the load terminals of my charge controller programmed to run an hour to two a day if that would help.

It's certainly not an every days deal. I also had it happen at a shed at an old house years ago on occasion. Seems to be only after certain atmospheric conditions, like warm ups after cold damp nights.

snobdds
Member
# Posted: 14 Jan 2021 18:34
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Quoting: toyota_mdt_tech
snobdds, I think you will get temp difference if it doesnt breath. Its what happened in my toolshed. Wasnt insulated, but after a cool evening, afternoon sun comes up and warms it all up, cold items inside all condensed with beads of sweat. Metal items were wet. I think the vents make temps the same, but the moving of air kept the humidity down.


I believe it works the other way. Warm moist air has to condense on a cold surface. Think of a cold glass of water in warm environment = Condensation. A cup of hot coffee in a cold environment does not condense.

This why I'm confused, A cold shed doesn't have enough warm moist air to condense on anything. Now if this was the summer and the shed stayed warm through the night and the night temperature dropped enough to cool the metal enough, it would cause condensation.

toyota_mdt_tech
Member
# Posted: 14 Jan 2021 19:07
Reply 


Hey, when I have a cold glass of ice water on a warm day, its full of sweat on the glass, this is exactly what happened to me with anything metal inside, ie tools etc. 2 vents, all cured. I suspect the vents just kept the air from becoming stale from not moving. The cold metal didnt warm up as fast as the air. After the vents, there was no more sweat. I mean zilch. And I live in an area that does have humidity.

NorthRick
Member
# Posted: 14 Jan 2021 20:10
Reply 


During your cold spell everything inside the shop got cold. Then it warmed up and, I presume, the humidity stayed high. When you opened the door the warm humid air hit the cold contents of the shop and condensed on their surfaces.

Short of heating the shop I don't think you can prevent this, just get things dried out as soon as possible after it happens.

paulz
Member
# Posted: 14 Jan 2021 20:44
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Rick I think you are probably correct. Next time I will pay more attention, not that there is anything I can do about it.

Thanks all.

Brettny
Member
# Posted: 15 Jan 2021 05:35
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Quoting: paulz
When I got here yesterday morning I opened one of the 8x8 doors, threw some stuff inside, left the door open and continued on to the cabin. Farted around there for a couple hours then went back down in the afternoon and noticed it, water droplets even on tools. So I don't know if it had been that way or happened after the door was open for a few hours.

Leaving the door open does this. Wild temp changes in the air with cold steel in the building will make things condense. Use a smaller door and leave it shut when its colder in the building.

toyota_mdt_tech
Member
# Posted: 15 Jan 2021 08:10 - Edited by: toyota_mdt_tech
Reply 


OK, can we add vents at gable ends? Keep temp equal and not a rapid change. Afterall, it worked for me. Never had the problem again. And its not heated.
Keep air moving too. Stale air and rapid temp swings is where the trouble starts.

WILL1E
Moderator
# Posted: 15 Jan 2021 08:19
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Quoting: Brettny
Wild temp changes in the air with cold steel in the building will make things condense. Use a smaller door and leave it shut when its colder in the building.


I bet this is why the last time i went up to my place i opened up my garage (8'x18' enclosed trailer) and lift the ramp door wide open and the side door open the entire day that i had frost building up on the ceiling when i went to leave. I would've thought keeping the doors wide open to let the air move through would have been a better idea.

toyota_mdt_tech
Member
# Posted: 15 Jan 2021 08:27
Reply 


I store my 7X16 enclosed trailer, I have 2, 14" roof vents with the Max Air covers and leave both vents open all the time. No sweat.

WILL1E
Moderator
# Posted: 15 Jan 2021 09:06
Reply 


Mine is sitting outside. I installed a side vent in the front corner and back corner. I didn't have any sweat in mine when i first opened it, but the ceiling had frost at the end of the day. So i'm guessing while it was cold outside, it was warmer inside thus the frost.

paulz
Member
# Posted: 15 Jan 2021 09:51
Reply 


Quoting: toyota_mdt_tech

OK, can we add vents at gable ends? Keep temp equal and not a rapid change. Afterall, it worked for me. Never had the problem again. And its not heated.
Keep air moving too. Stale air and rapid temp swings is where the trouble starts


Can do, but I think I will see if it happens again, as I expect it will as spring approaches and cold foggy nights give way to sunny, quickly warming mornings. I want to see if things outside, under my carport canopy for example, also do the same. Or, if in fact it was my opening and leaving the door open or if it was already wet inside.

Aklogcabin
Member
# Posted: 15 Jan 2021 10:16
Reply 


I would suggest a fan controlled by humidity. Or a humidistat. Check spelling. They are usually in bathroom exhaust fans. And will come on when moisture levels are too high. You wrote your building is well ventilated so you should have enough make up air to keep things moving.

paulz
Member
# Posted: 15 Jan 2021 11:36
Reply 


Quoting: Aklogcabin
humidistat


Great idea! At the old shed I mentioned, 12x20, I had a dehumidifier, about the size of a mini fridge, as it was on grid. It piped into a bucket outside, and did produce water. But again on those particular mornings it was just overwhelmed and the 8-10 motorcycles inside were wet.

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