Sizing sloped roof

[Larsa]

Hi
Need to brainstorm a bit and get some tips.... I'm in the process of expanding with 3x4 m outer dimensions. Ground floor in Leca, and an upper floor in wood with a wooden joist. The roof will slope outwards with a 20-degree incline (that is towards the 3-meter direction).

I thought the roof should be free to the "ridge," and the question is what dimension I need for the roof joists. The span will be just over 3m from the existing wall to the new wall.

For the floor, I was thinking of using 195mm C14 with glued particle board according to Träguiden's tables, but how does it work when it comes to the roof? Do you need to handle more load, or less?

I found this table http://www.traguiden.se/TGtemplates/popup1spalt.aspx?id=209&contextPage=1465 regarding roof beams. And according to it, I should use 145mm C14 CC 600, or alternatively 195mm C24 with CC 1200.

Can mention that I won't have space for 300 mm insulation, but 200mm should work.

All tips are welcome.

 

[Ola78]

Have you checked http://www.moelven.se or

http://www.byggbeskrivningar.se​

where there are sizing programs for calculating beams. Start by checking there and see what results you get.

 

[titanium]

Here you have Moelven's calculations. But unfortunately, it is only for their glulam and Kerto beams
http://www.iat.inadire.se/WebLagerbalk/Lagerbalk.aspx
I would guess 42x225 with c/c 1200.

But if I were you, I would use regular ungraded timber with c/c 600 (if you choose good timber) or K24 45x220 with c/c 1200.

 

[Larsa]

You mean regular 45x220 ungraded I assume. That seems quite reasonable, will be just right with insulation too.

Thanks for the advice.

 

[Larsa]

Moelven's program was brilliant, too bad it doesn't exist for regular construction lumber...

 

[Ola78]

Try the program at byggbeskrivningar.se where you can also find dimensions for common timber.

 

[titanium]

Try the program at byggbeskrivningar.se where you can also find dimensions for common lumber.

Tell us where :S

Larsa! Forgot to mention that I meant 45x220-lumber. Built such a roof last summer and it turned out stable "as concrete". Span 3400 and c/c 600. Feel free to place a 45-stud with insulation across the roof beams to counteract the many thermal bridges with c/c 600.

 

[Ola78]

Titanium, click on the dimensioning link and the program will start.

 

[Larsa]

Works well, but I had to calculate for an attached carport for my problem. It should match anyway since you could choose insulation and inner ceiling. Looks like C14 45x220 CC 600 is what I need. But I can't find ungraded timber, or is there a C-class that corresponds to unstamped timber?

 

[Bror]

I would choose 2 pieces of 45x195 CC 1200 on top of each other to accommodate insulation of sufficient thickness.

 

[Larsa]

I would choose 2 pcs 45x195 CC 1200 on top of each other to make room for insulation in sufficient thickness.

Unfortunately, I'm almost hitting my head on the ceiling then Simply don't have enough height for that, as I mentioned earlier.

 

[Ola78]

Larsa, not sure what insulation you plan to have but for example Isover has a board with a lambda value of 33 instead of the normal 36 or 37 http://www.isover.se/produkter/produktvisning?id=22548 I'm not sure if it is much more expensive, but you get slightly better insulation with the same thickness. Paroc has a similar variant http://www.paroc.se/channels/se/building+insulation/products/default.asp

 

[Larsa]

Thanks for the tips Ola78, I'll check it out.