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Small Cabin Forum / General Forum / Mold Problems in Cabin - advice needed
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bushbunkie
Member
# Posted: 10 Oct 2018 10:22
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Hello all,
There is some great experience within the folks in this forum....here's the problem:

As I have lamented before...in many parts of Ontario Canada it is very difficult to build a simple cabin without having to build it like a house - same building code exists for both (This is not what I want to discuss).
The cabin is a work in progress and I have now have it insulated to code (R50 ceiling - R24 walls - R20 in 4 ft crawlspace - Vapour barrier) and ready for Municipal Inspection. As the summer moved on I began noticing a musty smell when we came up on weekends. We then began noticing mold on our tables, chairs, behind dressers, etc. Three weeks ago, we left all the windows open four inches at the top....hate to do it for security reasons, but had neighbour keeping an eye. Arrived back last week and mold was same or worse! I know the cabin is now so darn airtight that it can't breath and the fluctuating temps cause humidity and moisture -unfortunately we do not have electricity, so I can't install an air exchanger or dehumidifier.
I don't think this prob will go away even when it gets colder and temps normalize a bit. Talking to a fireman buddy, he said I mayneed to create better air flow and opening windows a crack is not going to do it.
He suggested cutting a few vents in the floor (move 4 ft crawlspace air a bit) and opening the ceiling attic door on main floor and replacing it with a screened attic door so hot air can flow up into the attic and out my roof vents. I really do not want to continue to leave my windows cracked for obvious security reasons. I know there are some solar powered air circulation options available - but do not want this added expense if I can avoid it. Cannot have mold growing either as my wife has enough health concerns already.
Any thoughts?

xtolekbananx
Member
# Posted: 10 Oct 2018 14:24
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Is your cabin in a shade? Looks like you need some sun and good ventilation. They also sell moisture absorbers in plastic buckets, people use that in basements and it works from what I heard. I understand that open windows leave you thinking but if someone wants to get in they will throw a rock or something amd do more damage. I always keep a window open in the loft. What kind of heat do you have, wood stove helps moisture, unvented propane adds to moisture.

toyota_mdt_tech
Member
# Posted: 10 Oct 2018 15:27
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I think the convection idea might do it. A crawlspace sized door in floor, I didn't use a crawlspace access outside, made mine inside. If this is your scenario, open it up, open attic access and it should breathe well assuming attic space it vented. Air will move from bottom to top and out. I'd pull items away from walls and leave all doors in room open. Screens added to keep bugs out as you mentioned.

bushbunkie
Member
# Posted: 10 Oct 2018 15:28
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Hey XT.
Thanks for your thoughts...yes...more ventilation is what I am thinking with the plan to open up the attic door, etc.
Cabin is in full sun and we have woodstove for heating when we go up for weekends. The only inside propane source I have is our propane stove / oven which I keep right under an open window when we use it for normal meal prep. I "toasted" the cabin with the woodstove before we left last week, so we'll see if that helped at all.

bushbunkie
Member
# Posted: 10 Oct 2018 15:37
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Thanks Toyota...I respect your experience and looks like we are the same page. Actually I as thinking of vents in the floor but a crawlspace door may be a better idea...esp. for winter access in the future. Yes - the attic is vented...as per building code.
Will be easy to leave interior doors open - don't have those yet

NorthRick
Member
# Posted: 10 Oct 2018 17:04
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I wouldn't vent air in from the crawlspace as it will likely be high in humidity and make your problem worse. Maybe a vent in the bottom of a wall.

However, the problem seems odd given the cabin is in full sun. I'd also be looking to see where all the moisture is coming from.

rockies
Member
# Posted: 10 Oct 2018 18:18 - Edited by: rockies
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Everyone seems to be focusing on the mold but nobody is asking questions about the crawlspace or the roof.

You say you have a ceiling attic door. Is that because the cabin has a dropped ceiling throughout? If so what sort of eave and ridge venting do you have?

You also say you have a crawlspace. Is it vented or unvented? You should go to the Green Building Advisor website. They will tell you exactly how to build a crawlspace for your climate.

I suspect that the ventilation in your attic and crawlspace are either insufficient or non-existing and as such these spaces are becoming saturated with moisture which is then moving into your cabin interior (the moisture will be drawn towards the drier space). If your attic and crawlspace are improperly vented then creating new openings into the interior will only make things worse.

The three parts of your cabin - attic, interior and crawlspace - should be treated like separate sections and sealed off accordingly.

Just
Member
# Posted: 10 Oct 2018 18:22
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i have one of these at our cabin. unheated all winter keeps it dry
wind driven
wind driven


bushbunkie
Member
# Posted: 10 Oct 2018 19:25
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Hi Rockies...thanks for the info...here are a few more details...the cabin (1000 sq ft.) has been built to code and for our region and climate by a local builder. I don't choose my foundation or crawlspace - it is dictated by local building code. Blueprints had to be provided / approved, etc. and all steps in the build approved by the local building inspector to meet the provincial building code.
Crawl space is vented with four vents (has a 3" cement skim coat) and I have put an additional vent in the actual crawlspace door. Attic is vented with 4 -5 roof vents, etc.
It's funny that a recent code change is that houses / cabins now need air exchangers built in.
I think the underlying problem is that our provincial code was built for the housing industry (ie. house is built and finished in 6 months)….versus building over a few years. I believe the assumption is that anything you build now would have electricity, so you would not have any of these issues.

bushbunkie
Member
# Posted: 10 Oct 2018 19:26
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hi Just...yup...wife just mentioned those today - which might be part of a plan.

bushbunkie
Member
# Posted: 10 Oct 2018 19:29
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Hi Rockies....another note...was up in attic last week ...dry as a bone...no moisture on vapour barrier and my eaves and overhang on the porch all well vented with perforated metal siding.

rockies
Member
# Posted: 10 Oct 2018 19:49
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How about moisture levels in the crawlspace? Since you have no electricity I suspect that your source of heating would be a wood stove? Unless you plan on keeping a fire lit every day I wouldn't open the crawlspace up to the interior since the likelihood of cool moist air coming up from the crawlspace is greater than dry warm air going down from the interior.

You may have to turn the crawlspace into a "sealed, unvented one" or install a dehumidifier.

This article may help, but since you don't have electricity I would suggest joining the Green Building Advisor site (it's free to join) and posting your question in the forum.

https://www.greenbuildingadvisor.com/article/five-ways-to-deal-with-crawl-space-air

ICC
Member
# Posted: 10 Oct 2018 20:29 - Edited by: ICC
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Was the crawlspace design signed off on as a part of the permitting process? Did the authorities specify any details on how the crawlspace should be designed and built?

You mentioned a vapour barrier--- where is that? Over the ground, under the flooring, in the walls????


As an aside--- I am surprised they insisted on using what sounds like the same insulation and air sealing in the habitable space but let it go ahead without a HRV system. Or maybe the permit was issued before HRV was mandated--- at least my understanding is that a HRV (heat recovery ventilation) is required in everything new. Maybe I'm wrong on that.

But mold like that is a sure sign of too much humidity and/or insufficient air exchange on a scale that open windows is not going to solve.

Fanman
Member
# Posted: 10 Oct 2018 20:57
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I don't know how it's been in Ontario but in NY where our cabin is it's been a horrible wet summer this year and there's mold everywhere, even though we have lots of ventilation and everything is open. Other years have been no problem at all. My big question is how to best clean the mold off the wood.

rockies
Member
# Posted: 10 Oct 2018 21:09 - Edited by: rockies
Reply 


Fanman - don't use bleach, it doesn't work. Dish soap and warm water will work on surface mold or a product like Ulramean-2. Heavy mold should be left to a professional removal company. Wear a dust mask.

https://www.rhinohide.com/blog/never-use-bleach-to-clean-mold

cspot
Member
# Posted: 10 Oct 2018 21:18
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I know alot of people this year have had issues with mold that never did before. This is in PA and Ohio. Alot of schools districts had issues with mold as well. It has been abnormally extremely wet and humid this year for this part of the country.

Borrego
Member
# Posted: 10 Oct 2018 22:05
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Do you have water sitting under your cabin? I had a house in San Diego back in the 80's that developed a bad moisture problem and gave me severe allergy issues, all due to water/moisture sitting under the house, it was always damp even when it didn't appear to be so. I had to regrade and pour concrete to redirect the water....

Check the irrigation around your cabin and where the water runs or settles.....

bushbunkie
Member
# Posted: 11 Oct 2018 17:45
Reply 


Thanks guys!
ICC - The crawlspace was part of the design and signed off by Inspector. Its a common foundation choice on the Bruce Peninsula...we're all rock! Vapour barrier is on walls and ceiling - as per code. No vapour barrier on basement walls - because I had it spray foamed to R21. Was then getting mold in basement but after I opened crawlspace door for a week, moisture stabilized. I think you are right re. the air system....my permit was in 2014 and they now have just made air exchange mandatory code...probably because of problems like this!
Fanman / CSPOT - agreed...it was one wet humid summer in Ontario as well. I'm hoping this is going to be an isolated incident due to the temp extremes we had this summer.
Borrego - No standing water...have proper drainage tile all around cabin. Crawlspace is dry.

bushbunkie
Member
# Posted: 11 Oct 2018 17:46
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Cool video - thanks XT...that could actually work and it's cheap!

creeky
Member
# Posted: 12 Oct 2018 13:13
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These things are really cool .

Friend of mine installed the fancy european version. They are super easy to install and work great.

bushbunkie
Member
# Posted: 12 Oct 2018 16:20
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Thanks Creeky...unfortunately the challenge is I have no hydro hooked up...strictly generator right now.

ICC
Member
# Posted: 12 Oct 2018 20:45
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Well designed solar could run that.

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