ᐅ Attic Conversion – Use OSB or Drywall?

Since we are already on the topic, related to the other discussion Attic Storage Expansion

We are still undecided whether to use OSB boards or drywall (plasterboard) directly for the renovation. Unfortunately, even after talking to various friends and acquaintances, we haven’t become much wiser 🙁

Can anyone share some insights on the pros and cons....?

Thanks a lot in advance 🙂

For the attic conversion (walls, ceilings), Fermacell boards are used less often than OSB boards but as an alternative to drywall panels.

Fermacell boards are not as smooth on the surface as drywall and generally need to be fully skim-coated. With drywall, only the joints and screw holes require filling. Drywall panels are less dimensionally stable and less durable on the surface compared to Fermacell or OSB. Drywall swells irreversibly when exposed to significant moisture, unless moisture-resistant (green) boards are used. Both drywall and Fermacell boards can be scored and snapped for cutting, whereas OSB boards must be cut with a saw. Regarding fire protection, drywall and Fermacell are roughly equivalent, and there are special fire-rated panels available; OSB is less suitable for fire protection. Special anchors can only be partially secured in drywall and heavier loads usually need to be attached to the framing. OSB is best suited for this purpose.

This is what I quickly noted.

Gypsum board, because I believe it is more vapor-permeable.

Sorry, I meant rough-sawn boards, not drywall. Rough-sawn boards are optimal.

Allthewayup schrieb:

For attic conversions (walls, ceilings), Fermacell boards are used less often than OSB and serve as an alternative to drywall panels.

Fermacell boards are not as smooth on the surface as drywall and usually require full-surface jointing. With drywall, only the joints and screw holes need to be filled. Drywall panels are less dimensionally and surface stable than Fermacell or OSB. Drywall swells irreversibly when exposed to excessive moisture (unless the green moisture-resistant boards are used). Both drywall and Fermacell boards can be scored and folded when cut, whereas OSB panels must be sawed. In terms of fire protection, drywall and Fermacell are roughly equivalent, with special fire-resistant boards available; OSB is less suitable for fire protection. Anchors (special types) can only be partially secured in drywall, and heavier loads must be attached to the framing. OSB is best suited for this purpose.

That’s what came to mind quickly.

All right. Thanks for the great help and explanation.

Oh yes, one more thing to consider: older particleboard is currently criticized for its formaldehyde emissions. Whether this is still the case today, I unfortunately do not know. I am sure that there have been improvements, but what exactly has changed remains unclear. New types of drywall boards like "ActiveAir" are said to absorb and neutralize formaldehyde from indoor air. However, it is also important to approach these claims with a critical mindset to understand how this actually works or is supposed to work.