Hello,
I started building over a year ago, and we have since moved in.
The upper floor was finished with roof battens, drywall panels, a vapor barrier, and insulation installed above it, all inspected and approved by a building inspector. The insulation and tests underneath still show positive results; everything remains completely dry.
Now, I want to screw OSB panels, which have been stored in the attic for about a year, onto the joists above the insulation.
However, I am a bit uncertain about the risk of mold growth. Everything is currently dry, and the vapor barrier is properly installed.
A wood moisture meter showed that the OSB panels have a moisture content of 5-10%, which the device indicates is low.
Still, I am concerned about mold.
Should this installation work, considering the panels are unlikely to ever be 100% dry, and any moisture would—if at all—rise upwards? I plan to leave about 2-3 cm (1 inch) of space around the edges to allow the panels to expand. However, this would mean the installation is not completely airtight.
Is this approach safe?
I started building over a year ago, and we have since moved in.
The upper floor was finished with roof battens, drywall panels, a vapor barrier, and insulation installed above it, all inspected and approved by a building inspector. The insulation and tests underneath still show positive results; everything remains completely dry.
Now, I want to screw OSB panels, which have been stored in the attic for about a year, onto the joists above the insulation.
However, I am a bit uncertain about the risk of mold growth. Everything is currently dry, and the vapor barrier is properly installed.
A wood moisture meter showed that the OSB panels have a moisture content of 5-10%, which the device indicates is low.
Still, I am concerned about mold.
Should this installation work, considering the panels are unlikely to ever be 100% dry, and any moisture would—if at all—rise upwards? I plan to leave about 2-3 cm (1 inch) of space around the edges to allow the panels to expand. However, this would mean the installation is not completely airtight.
Is this approach safe?
Then moisture can get under the OSB boards in summer, right? Yes, that is correct. But the real issue isn’t “humidity,” it’s “condensation.” As long as the dew point in your top floor ceiling isn’t reached in summer, you don’t need to worry (and it definitely won’t be!).
The real problem with OSB in summer is more about the limited drying of insulation moisture that may have accumulated there over the winter. That’s why I recommend generous gaps and spacing when installing.
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