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Small Cabin Forum / Cabin Construction / Advice. Mold in brand new Cabin
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HLC820
Member
# Posted: 26 Jul 2019 23:43
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We just had a 16x20 cabin built in southern Vermont. It is 4 season, so insulted and has vapor barrier. It was completed late April. We visited in the end of May and end of June with no issues. Came back today for the weekend and the entire floor (still plywood) is covered in green/black mood and white powdery mold. The window sills and gram around windows have it as well. The builder is at a loss and has never ever had this happen. Everything was wrapped and insulated appropriately, we are assuming. It’s been HOT and humid here but that shouldn’t cause a properly sealed cabin to have this happen. He said possibly the wood that was delivered was moist? We are meeting him at the cabin in the morning so he can see it but unsure what or how to remedy. Currently at a hotel because it cannot be safe to breathe in for us or our small children and dog. Any insight would be appreciated.

Atlincabin
Member
# Posted: 27 Jul 2019 00:13
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Sounds to me like green wood. I stored some rough-cut boards stickered but also loosely wrapped in a tarp in my shed over one winter and came back in spring to some pretty molded wood that sounds about like what you are seeing. If it (the cabin) was sealed up fairly tightly and there was moisture trapped inside, it is not surprising to me that it could mold in fairly short order in hot weather.

I would think the builder should make it right (which in this case may mean starting over).

HLC820
Member
# Posted: 27 Jul 2019 00:23
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If that is the case, the only remedy is completely tearing the entire cabin down? I mean, it’s finished, we just hadn’t put hardwood floors down yet. It was a pre cut kit that a builder who works for them assembled, but we hired separately. We’d have to buy an Entire new kit to replace the entire structure?

DaveBell
Moderator
# Posted: 27 Jul 2019 00:53
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Quoting: HLC820
buy an Entire new kit to replace the entire structure?

And if it happened again?

I would buy a garden pump sprayer ($20) and spray it with 50% bleach solution. Can you post some pictures of inside and outside so we can see how bad it is and other options? Is there electric?

HLC820
Member
# Posted: 27 Jul 2019 07:19
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No electric. We are at a local hotel so I only have 1-2 photos from last night with no lighting. This is what’s covering the entire floor and some planks of the wall and window sills.
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FishHog
Member
# Posted: 27 Jul 2019 08:40
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do you have any ventilation, or was it sealed up with all the moisture you introduced during your last visit and left in the hot weather.

Ventilation is the key, or moisture builds up and moisture equals mold.

I would get some windows open first, then figure out your options, but if its closed up that mold will keep growing.

Sorry this happened to you, but good luck. Perhaps best to speak to a mold expert

creeky
Member
# Posted: 27 Jul 2019 08:57
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Dry the place out. Hit it with bleach as recommended. Then there are some paint sealers. I had something similar (but not as bad) when my winter place was first sealed in.

Once the wood dried out a bit (and the window was left open) I painted. Its been fine. No mold.

There are some really good ventilators now. Google "erv hrv single room"
They basically breathe. Blow air out/breath fresh air back in. And use a ceramic energy recovery cartridge to reduce the cost of the fresh air.

Good luck.

mj1angier
Member
# Posted: 27 Jul 2019 12:03
Reply 


Yeah, odds are it rained during the build or wood was wet. Then the building got dried in and wraped up tight. Damp is still in the wood and add heat... mold.

I would clean with bleach solution and at least get fans blowing on it to help dry it out. The best would to put a dehumidifier in there to dry it out. If not any power you can put down a layer of cat litter to help dry it to start, then a few shoe boxes full till it gets drier.

ICC
Member
# Posted: 27 Jul 2019 13:41 - Edited by: ICC
Reply 


Get a moisture meter so you can see what the moisture content is. Construction lumber should be 9 to 14% max. Wood flooring should be 6 to 8 % max. Wood that is 20% or higher readily supports mold growth. Also if the moisture level is higher than 15% or so you may have problems with paint not adhering properly.

Common bleach is not the best product to kill mold on wood. The chemical structure of bleach makes it unable to penetrate porous surfaces like drywall or wood. So the surface mold is killed but the roots are left behind. If the wood is still too moist the mold can regrow. Bleach is great on hard nonporous surfaces.

Have a look at https://moldpedia.com

Best of luck.

Brettny
Member
# Posted: 28 Jul 2019 08:19
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Do NOT use Bleach. All it treates is the surface mold and it will be back. Use 50/50 white vinegar and water in a pump sprayer. Soak everything thats moldy or close to moldy before it spreads. You also will need fans and to leave the windows open.

This looks like wet building materials that were built with quick and sealed up tight quick. You need to get that place airing out and dry. Fans at first then a dehumidifier. You will need power to get all this done. If you dont have power spray with vinegar solution and keep as many windows open as you can.

I use to have mold in my attic. This is how i know bleach/water dosnt work and vinegar/watet does. Bleach is also terrible stuff to breath when sprayed.

bushbunkie
Member
# Posted: 29 Jul 2019 07:27
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HLC820, we ran into the exact same problem. We built a 1000 sq ft shell and all was good until I insulated the building to the required code...including the crawlspace. We came up and started smelling a musty smell...then noticed mould on the furniture and even some moisture inside the plastic vapour barrier on some walls and on the 2x10 beams in the crawlspace. The problem wasn't the wood...the place was sealed to tight...couldn't breath...new builds usually have electricity, so you have air exchangers going...we have no hydro and only go up on weekends. I would take Creeky's advice. Leaving the windows open works for the cabin, though now security is compromised...but oh well. I'm looking at getting a solar powered fan for the crawlspace right now...our builder said he has never seen so much moisture as this year (Ontario - Bruce Peninsula). He said many people are complaining about mould and dripping pipes in their crawlspaces due to humidity.

creeky
Member
# Posted: 29 Jul 2019 08:14
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Quoting: Brettny
50/50 white vinegar and water in a pump sprayer. Soak everything thats moldy or close to moldy before it spreads.


Wish I'd learned that one earlier. thx

Princelake
Member
# Posted: 29 Jul 2019 09:17
Reply 


There are mold control products that you can buy even at home depot instead of mixing your own brew. Spray it down with a pump sprayer get the place good and dry to the moisture levels to what icc says then I'd get like a mold stop paint from zinesser or a heavy duty shellac base paint to encapsulate it and seal it off from growing.

Brettny
Member
# Posted: 29 Jul 2019 13:25
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The vinegar works so well in about 15min i could see a difference.

I have a friend who used the mold stuff from the big box store. He said it just smelled like bleach but cost 10x the price of bleach.

Since this is a new house personaly i would get a quote from a real company so your able to possibly get some money back from the builder. You dont have to go after the builder but if it becomes a bigger issue it may be necessary.

offgrididaho
Member
# Posted: 29 Jul 2019 14:04
Reply 


If you're not tearing it down, consider a heavy duty dehumidifier (like a commercial one that you run for only a certain number of days or you'll dry things out too much) and a commercial ozone generator to kill all the mold.

JDH83VT
Member
# Posted: 30 Jul 2019 11:52 - Edited by: JDH83VT
Reply 


Also in southern vt, hello neighbor! I'm assuming you bought the kit through JCS... I toured their yard and if I remember correctly, it looked like they were using a lot of green lumber. x2 on the vinegar solution, get some fans and open up the windows when it isn't so humid. Couldn't hurt to grab half a dozen small buckets of damp-rid from the hardware store if you don't have the power to run a dehumidifier. After it dries out you can coat with some mold inhibiting paint as recommended above. You should be fine, I wouldn't think you'd need a tear down. I had the very same situation at my camp when the subfloor got wet before I finished the roof. I quickly got the place dried in and sealed it up tight without letting things dry out properly. It's been a couple years now with no recurrence.

Blaze
Member
# Posted: 31 Jul 2019 11:27 - Edited by: Blaze
Reply 


@Bushbunkie did you install crawlspace vents?

Blaze
Member
# Posted: 31 Jul 2019 11:40
Reply 


This is why I am a huge fan of advantech style subfloor. More expensive but a great product

bushbunkie
Member
# Posted: 1 Aug 2019 07:06
Reply 


blaze...Yes...4 vents and have made the crawl space door a screen door to keep a breeze going 24/7...all was good till I insulated the crawl space walls for city inspection

jos_davies
Member
# Posted: 8 Oct 2019 05:33
Reply 


HLC820, how is it going?

I had a similar problem in the past, lesson learned. We had some serious issues with humidity and air conditioning, as for now it was completely fixed, but had some troubles fighting with mold. Though it was growing in insulations.

First step would be to take insulation out.

Run a dehumidifier if it is damp. I rented a commercial one, like offgrididaho
mentioned.

Next - buy a cheap sprayer from home depot and a few gallons of Concrobium (it is an odorless, safe way to kill mold).

I then got my kids old little reg wagon, a wire brush, a mask, an old hat and I sprayed the whole beams and floor boards. Then I used a wire brush where mold was tougher and scrubbed.

Next day I did it again on remaining areas.

Final day used some plain old bleach. Bleach is not great at killing mold but good at removing stains from dead mold.

Left installation off for a few weeks and ran my regular humidifier, then replaced insulation.

One neighbor who had a newer house the "new wood" soaked up water like a sponge when damp after he did the mold remediation he got a paint sprayer and actually painted crawl space roof with oil paint. Mold won't grow on it.
As another precaution - check your crawl space ventilation: add vents, install a dehumidifier (here are some models, our is Aprilaire and it was tricky to install, but worth it), make it dump proof to prevent situations like this.

I hope you'll be able to save your cabin!

DaveBell
Moderator
# Posted: 13 Oct 2019 20:42
Reply 


Quoting: Brettny
Do NOT use Bleach. All it treates is the surface mold and it will be back. Use 50/50 white vinegar and water in a pump sprayer.


Ok, just tried straight vinegar on some mold spots in the shower, soaked for one hour, and it didn't do a damn thing. Going back to bleach - at least it works.

Brettny
Member
# Posted: 15 Oct 2019 08:10
Reply 


I found bleach to work for about a month. It came back. Vinegar its been over a year.

LittleDummerBoy
Member
# Posted: 24 Aug 2020 17:10
Reply 


I have a cabin in NH. Leave some ventilation or it gets damp.
Use the bleach, then use your wood stove.
Raise the cabin's inside temperature to 140° +.
That kills mold. The longer you keep it hot, the deeper into the walls you'll kill the mold.

Rickkrus
Member
# Posted: 25 Aug 2020 20:08 - Edited by: Rickkrus
Reply 


20% vinegar

SE Ohio
Member
# Posted: 25 Aug 2020 20:49
Reply 


Some mold remediation professionals use hydrogen peroxide. A friend once accidentally bleached his exposed hair! Wear protective gear...

SE Ohio

toyota_mdt_tech
Member
# Posted: 26 Dec 2020 14:42
Reply 


Remove mold, carefully, allow cabin to fully dry, maybe leave some windows cracked to get moving air. I think sealed up tight is great, but if its shut up tight, temp difference great from inside to outside, this will happen.

Mine is closed up tight in winter, but I have a dry environment. Low humidity.

gcrank1
Member
# Posted: 26 Dec 2020 15:04 - Edited by: gcrank1
Reply 


Hey Dave Bell, if vinegar doesnt touch the black mold it may not be mold, especially that stuff in a bath/shower enclosure. It may be the bacteria Serratia Marcescens and it does respond to bleach treatments.

gcrank1
Member
# Posted: 26 Dec 2020 17:52
Reply 


So much good advice. Wonder what ever happened with HLC820 and this?

DaveBell
Moderator
# Posted: 26 Dec 2020 18:44
Reply 


Quoting: gcrank1
Serratia Marcescens

Is red at room temperature.

BobW
Member
# Posted: 27 Dec 2020 12:44
Reply 


Borax mixed with water and scrubbed on the mold in the old mountain house got rid of mold and it has not come back two years later. House has propane heat when vacant during the winter and is damp.

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