Fire rating EI 60

[Lcms]

It is said that there should be double gypsum on both sides, can one replace one of the gypsum boards with, for example, OBS instead? They have the same fire resistance, about 15 minutes.

 

[Nils82]

Sorry, two layers of plaster or one layer of fire-rated gypsum and fire sealant around and intumescent fire sealant or collar around penetrations that are sensitive to fire.

However, you can use OSB behind one of these options. The wall will unfortunately become quite thick, if that's a problem, that is.