Dimension of battens!

[robban_78]

Planning to install a metal roof of the type Plannja Royal Hardcoat and have tramsäkerplast as the underlay with cc1200 between the rafters.
Also, snow zone 3 Norrland, but what thickness should the battens be, should it be 45*70 or 45*90? I've checked Plannja's website but can't find an answer.
Grateful for help!

 

[RiKr]

Plannja usually has a PDF available for download with assembly instructions, have you checked it out?

 

[Liteavvarje]

Push the scattered battens together to C/C 600; it can be 16X70, and lay 28X70 on the slab to hold it. It's a good thickness to screw into; the lower the new one comes, the easier it is with the fittings, chimney, gutters, etc. Once you lay the sheet, you can't reach anything underneath without tearing half the roof apart. I have royal but used pressure-treated for the scatter and carrying battens; I probably never have to worry about the roof again—it’s been 15 years. Royal requires a fairly precise scatter laying.

 

[RoBo]

Push together the battens to C/C 600 can be 16X70

?? on the walkable plastic ?

 

[Liteavvarje]

?? on the tramp-safe plastic?

If it's plastic then I haven't seen it before, my royal is metal, a big misunderstanding if that's the case, but he writes metal roof, so my thought was on that, we'll see what he says.

 

[robban_78]

As I understand it, I should have 45*90 as the load-bearing batten. The reason I'm asking is that I want to be sure because the hired carpenters have started nailing up 45*70 load-bearing battens. Doesn't feel too good, I've had trouble with them before, and it might get even more complicated now if I have to point out that they are using the wrong studs.

 

[justusandersson]

In plannja's assembly instructions, there are details on the appropriate dimension of the battens for different snow zones and underlay types. In your case, it should be 45x95. However, the difference between 45x70 and 45x95 in the weak direction is not significant. A 70x70 is much stronger than a 45x95.

 

[RiKr]

Assuming it's in snow zone 3 or higher, it says 45*95. However, I would like to believe that the angle of the roof is equally important.

 

[justusandersson]

However, I want to believe that the roof angle is just as important

The roof angle affects the snow load size. Over 30 degrees, the snow load is reduced proportionally, so that it's half at 45 degrees.

 

[Liteavvarje]

Maybe a thought with 600 C/C from me on the ströläkt, but do they have it?

 

[RiKr]

The roof angle affects the snow load. Over 30 degrees, the snow load is reduced proportionally so that it is half at 45 degrees.

Yes exactly, if he has a 14-degree slope, it might be suitable to have 45*95, with 45 it should work well with 45*70.

 

[robban_78]

The pitch angle of both the high and low parts is 20 degrees, the high part is 6m wide and both low parts are 4m wide each.

 

[RiKr]

Maybe a thought with 600 C/C from me on the battens, but do they have that?

No battens as the roof has no boarding, it's called a light undersheathing.

 

[justusandersson]

It may be interesting to compare the deflection at maximum snow load 3 kN/sqm, c/c for the rafters 1200 mm and for the battens 375 mm. The reference value 1/300 of the span (i.e., 1200 mm) is 4 mm. 45x95 gives 3.7 mm and 45x70 gives 5 mm! You need to have good eyesight to notice that difference.

 

[Liteavvarje]

OK, I give up, too high a school with unsupported for me, you know better ,only with a normal roof for me