I have recently had a 24 by 44 polburn built with green lumber by the Amish, and on the second floor and a little bit on the first it's starting to mold. What do I do? I have nothing in the barn yet because I was just gonna let it set and dry out until the end of summer. But I was wondering if I need to be concerned about the mold growth at this moment
What kind of lumber? Two I've built out of red pine have both had that issue. Let it dry out and it'll probably stop. I let mine dry out then sprayed over it with a 50/50 mixture of diesel and used motor oil using a cheapo $40 airless paint sprayer (I use it with that same mix to rust-proof some of my cruder farm/bush equipment).
There's probably more 'proper' methods, involving bleach, borax, naphthenate, etc.. But it's probably fine once it's dry. And even if not, I figure no self-respecting bacteria or mold is going to survive too well once it's dried out and sprayed with that diesel/oil mix. Plus that's what all us farmers use to coat our flatbed decks on trailers/wagons, so it's a (kind-of) proven poor-man's preservative.
can you open it up? needs to dry faster, and a mix of bleach water will kill what is going on. As far as health goes, most common mold is not harmful to humans, but you can get an allergy to it if around it much and prone.
Building with green lumber is OK, but you must let it dry out before things are fully closed up.
Airflow is your friend. I assume the 2nd floor is more enclosed, so the drying is slower up there. If you have power available, some fans to move air though the building should help. Basically if wood is over about 20% moisture, then mould and fungus can grow on/in it. Once it gets below about 20% there ins't enough moisture there to support the growth. An unheated structure will probably end up 10-15% moisture, depending on where you live, which is fine.
Hit it with a spray of dilute bleach to knock the mould back, and work on getting it dry. Don't worry about the bit of water you spay around, that only affects the surface and will dry out that day.
I'd be a little hesitant to use any bleach because it will rust any metal it gets on. If you do use any bleach solution only use a 2% bleach solution. People think more bleach is better, but not so. Studies have shown that more than 2% is no more effective than 2%. Definitely don't exceed 5%.
The outside of the wood is obviously moist enough for mold, and above 50F will mold. It only takes a week-2 weeks with sufficient airflow to stop mold growth on the outside. Sufficient air flow being the key. Also, it should not be growing below 50F as I said.
Yeah, dilute bleach like you might use to mop the floor. A cupful in a bucket of water sort of mix. 30% bleach from the supermarket mixed 15 to 1 would be ~2%. Enough to knock back the mould, not nasty enough to cause problems.
It just knocks the mould back and gives you a few more weeks to get the place dried out.
WOW, 30% supermarket bleach? I'm lucky to get 10% chlorine at the pool supply at $8-9/gal. Our laundry bleach is 4% for name brand, 2% bargain brand.
I may have mistaken the concentration for some others from my gold refining experiments box. :-\ But dilute it like at says on the bottle for general cleaning and you will be about right.