OSB span roof

[kalubah]

Going to stretch ceiling panels between my rafters at 1.2m centers. Since I want the smallest possible construction height (every cm is important), I was planning to put an OSB on each rafter and a 13mm gypsum board on top of this. I'm a bit unsure about OSB, can this span be okay? A plywood board would probably work fine, but hardly a chipboard - OSB is somewhere in between in strength, right?

 

[FredrikR]

Since gypsum 'requires' cc30 in the ceiling, I don't think an OSB board behind it will prevent it from sagging at cc120, unfortunately.

 

[kalubah]

I should add that it is a 45-degree sloping ceiling, so there is a certain rigidity in the direction of gravity.

 

[Bergling]

cc120 sounds a bit too much just for OSB. If the centimeters are really that important, an alternative could be 22 mm råspont. But otherwise, gles is probably preferable.

 

[Farzan]

A plywood board would probably work fine, but hardly a chipboard - OSB is probably somewhere in between in strength?

There is strength and strength... screws hold well in OSB but in terms of bending stiffness, I experience, from my own experience and without having seen any figures on it, that OSB is rather more flexible than chipboard of equivalent thickness. By the way, I probably wouldn't even use plywood in this way. So I agree with the previous - slatted.

 

[hempularen]

A variant I know some people use is to install false trusses, i.e., trusses of smaller dimensions between the real ones.

 

[kalubah]

A resounding no then
I guess I'll go with råspont then.