sala on roof trusses cc1200

[Marbu]

Hi!

I am currently furnishing our upper floor, is it okay to use 45x45 cc600 crosswise over cc1200 trusses?
The plan is to then have sparse paneling and plasterboard.

I was wondering if it would be too unstable or if it's too wobbly?

Best regards, // Markus

 

[justusandersson]

In a horizontal ceiling, the boards will sag about 1.5 mm at the middle if you only consider the weight of 45x45, sparse panel, and plasterboard, assuming that the 45x45 timber is C 14 graded. Isn't it better to use 45x70 (should be available in C 24 grade) on edge with c/c 300 and skip the sparse panel?

 

[Marbu]

In a horizontal ceiling, the boards will sag about 1.5 mm in the middle if you only account for the weight of 45x45, sparse paneling, and gypsum, assuming the 45x45 wood is C 14 classed. Isn't it better to go with 45x70 (should be available in C 24 class) on edge with c/c 300 and skip the sparse paneling?

Thanks for the detailed answer!

I prefer sparse paneling for the electrical installation, and I have a vapor barrier against the 45x45.

The thing is, I've already started setting 45x45 against the trusses, so if they are really not recommended, I'll have to reconsider. It's a sloped roof at 27°.

Isn't it quite common practice to set crosswise lining against the trusses to minimize thermal bridges? Do you perhaps use 45x70 lying down instead?

 

[justusandersson]

27° pitched roof is a plus in this context, the 45x45s can take up the load a bit more diagonally, to put it simply. A disadvantage of that dimension is that the quality is often poor and they are definitely not strength graded. In that case, 45x70 C 24 on its edge is much better. As I understand, you've already put up the studs, so I would probably let them stay.