We hear again and again about mold attacks in roofing plywood and windbreak boards. Can't something be done to prevent it?
Yes, as the picture shows, plywood has been installed in this construction as a wind barrier. The difference is that the one plate in the picture was treated from the start Protox Aquaground, and the other was untreated – guess which one?
Moisture and temperature variations in roof plywood cause mould
Even if the ventilation in the roof space is carried out according to all regulations, there is an imminent danger of mold getting on the roof plywood in such a construction. This is due to the natural moisture and temperature variations in that construction.
When the sun shines on such a roof surface, it gets hot like 60 degrees. This means that the air inside the roof space also becomes very warm and can therefore contain a lot of moisture. When the sun goes down, the temperature of the roof veneer drops rapidly, and the cold surface gives rise to condensation.
The moisture that condenses on the plywood can only "be" in the outermost 1.5 mm thin veneer layer, because just below that there is a completely waterproof glue joint into which the moisture cannot penetrate. This means that the upper veneer layer very quickly is moistened to above the critical 15 % wood moisture, and then mold growth occurs.
How to prevent mold in roof plywood
The right way to prevent it is to treat the underside of the roof plywood with Protox Aquaground, before the installation. ProtoxAkvagrund is an approved wood preservative that prevents both mold and wood-decomposing fungi. With a MAL code of 00-1, it can be applied with a simple garden sprayer and once and for all solve the problem before it occurs.
If there is mold growth as shown in the picture, cleaning is included ProtoxHysan of course a possibility, but it is many times easier, not to mention cheaper, to prevent than to cure.
Read more about growing conditions as well as treatment and prevention of mould here.