ᐅ Two layers of drywall or OSB plus drywall

Hello everyone,

I had a drywall contractor at the house yesterday for a quote. He said he would install a layer of OSB boards under the insulation in the attic, and then a layer of drywall on top. He said it’s cheaper that way than using two layers of drywall (makes sense).

Is this an acceptable approach? Any disadvantages? This would also be the case in the bathroom (of course with moisture-resistant drywall).

Best regards!

We are also using OSB plus drywall. The advantage for us is that we can easily attach things with Spax screws. With drywall alone, you would need drywall anchors.

Do you experience this in the bathroom as well?

Yes, and the cabinets have held up without any issues for four years. In that case, it is the green moisture-resistant drywall.

Exactly, I was just worried that moisture might seep through and cause the OSB to swell. Thanks for the information!

Use Fermacell. They are thinner, significantly more durable, and suitable for damp rooms. They cost a bit more, but you need slightly less substructure.