Mold or fungus in my wood

Hello everybody,

I need you help because I don't know what else to do.


I built a cabin in a very humid forest in Colombia. I used pine tongue & groove wood for the triangle you see in the photo.


But this wood is filled with mold (I don't know what it is exactly) on a recurring basis, we have cleaned it and covered the wood with polyurethane but after about two months it comes out again.


What treatment could I give the wood to prevent this from continuing to appear?

https://drive.google.com/uc?export=v...3v73Hg_c4esGRR

https://drive.google.com/uc?export=v...Sf0SNH7g-jkJ19

Thank you for your help!

JoseAttachment 509026Attachment 509027

Hi jdbravo,
It's a long time since you asked your question and it's still not answered! Have you solved the problem yet?

I imagine you've confirmed there is no water ingress, it's just the humidity in the air creating the moist conditions?

This suggestion may not be adequate for your situation given the humidity and the apparent exposure to the elements but it's how I'd tackle it.

As it's a fairly large area already conveniently divided into sections, perhaps deal with one at a time, starting at the top.

As you have already semi-sealed the surface you may have to strip it to allow any mould-killer to penetrate.

Pre-treating with bleach or full strength vinegar may not be enough given the constant humidity. You may need a fungicide. Ask at your local health department, university or paint supplier for a recommended procedure as the problem must be encountered frequently. Whatever is the recommended remedy treat one section at a time. Dry that completely with a heat gun until it's almost flammable.

When it's completely dry, varnish that section immediately, with clear varnish. Or, if you're willing to give up the natural wood surface, pigmented shellac followed by a topcoat of your choice. Also check out KILZ(R) MOLD & MILDEW Interior & Exterior Primer | KILZ(R) for added encapsulation. Move on to the next top section, repeat.

That's simply a suggestion. I haven't done this. But based on everything I read when I was looking for info on mould supression for a tile problem in a former house (I'm easily distracted so read everything non-tile as well) this is the plan I would try if confronted with your problem.

Good luck with it. Let us know if you solve your problem.

"covered the wood with polyurethane"

That's the doomsville moment right there.

The hongo is under the poly and there is no amount of wiping that's going to get rid of it.

I suspect the only solution is to strip the wood, acid wash the wood, and use an exterior OIL to repel any moisture.

My2c.

First. What a lovely building!

By the way, the photo doesn't look like pine. Are you sure?

As mentioned earlier, polyurethane on the wood has stopped it breathing - and with your local humidity and temperature - it is going to be a mould and fungus heaven.

The second problem is that it is sealed ON THE OTHER SIDE TOO, because I see what looks like non-breathing bitumen shingles placed DIRECTLY ONTO the wood without any breathing airflow. The design and choice of construction is poor. Those bitumen shingles are awful. They will capillary action draw rainwater under the shingle and there is nowhere for it to do. In Europe, such shingles are used on garden sheds, and the wood they are placed on, runs in the vertical direction, with fluting to allow trickle airflow/condensate to move.

a) airspace above preferred, even if very minimal
b) non-sealing treatment underneath, ie. not polyurethane

I think it is beyond economic to try to fix what you've currently got. With the wood in-place, trying to get stripping chemicals under the eaves is just not practical.

Accept that the working life is short due to design flaw. Get ready to replace it, and do it differently next time.

I hope that the roof of the main building is better!