black mold on OSB ceiling panels

Hello everyone,

we have a shed roof with a 3° pitch. OSB panels were installed on the roof beams and insulation was placed on top (walkable thermal insulation boards). Now plastering and screed work have been carried out. Black mold has formed on the entire ceiling (due to rising moisture).

The statement from the construction company is: That can be wiped off again.

I do not see it that way, as even killed mold spores can be harmful to health and they have certainly penetrated the OSB panel.

Do you know of any rulings, studies, technical regulations, or similarly strong arguments that state that the panels definitely need to be replaced?

Thank you very much in advance for any tips and advice!

What does the construction supervisor say?

We do not have any other construction supervisor. I am more looking for facts that indicate the panels need to be replaced.

That can be wiped off again.

Then the construction company should do that promptly (so tomorrow, around 7 o'clock). And take measures to prevent new mold from forming. That would be okay and sufficient for me -- based on your posting.

Then the construction company should do that promptly (so tomorrow, around 7 a.m.). And take measures to ensure that no new mold develops. That would be okay and sufficient for me -- based on your post.

???

Have I missed the sarcasm button here? I actually got to know you as a rather "prudent" builder in this forum. The spores spread into the air when wiping and can then be harmful to health – even some time after wiping. Not to mention that this black mold certainly does not only contain killed spores.

Regardless: It has been discussed here many times that OSB boards should only be installed once the house is standing and has been drying for about a year. I do not understand that a construction company installed the boards even though damp plaster and screed are applied only later. It’s almost as if the construction company called the Schimmel family: "We have something for you."

Did I miss the sarcasm button here?

Hmm, yes, in hindsight now . It would at least be a start. If the construction company casually says "It can be wiped off," then the question pops up: So what? Then just do it, you idiot, and don’t talk nonsense. Maybe as a punishment for this ignorance one has to insist on a complete replacement. I don’t know ....

They are supposed to start heating these days. I reminded once more that the drywall installer should come as late as possible. The site manager also confirmed that, it corresponds to his usual practice. Currently, the top floor ceiling is not covered from below. You can see the sealed vapor barrier (foil) there. Possibly, it’s also a ventilation problem if drywall or OSB boards mold. I hope for the best ...