I know that cc 120 is recommended for rafters.
I am going to build a woodshed with a roof pitch of 22.5 degrees and an uninsulated roof to be covered with regular clay tiles. For practical reasons, I want to have cc 155 but how bad is it on a scale of 1 to 10 where 10 is really foolish? I live in western Sweden where the amount of snow is limited.
I am going to build a woodshed with a roof pitch of 22.5 degrees and an uninsulated roof to be covered with regular clay tiles. For practical reasons, I want to have cc 155 but how bad is it on a scale of 1 to 10 where 10 is really foolish? I live in western Sweden where the amount of snow is limited.
I would say 7, not quite understanding your distance between the rafters, if it's a division, then why not reduce the measurement to about a meter. Naturally, you can compensate with raw boards about 28mm. But still, keep in mind that tiles weigh a bit, and over the years it will sag between the rafters, as the raw boards there will follow the damp weather in western Sweden.
17 mm is enough if you have cc 120.
Now that you want to go over that, you should compensate with råsponten.
Personally, I would have rather gone the other way, that is, reduced the cc between the rafters, especially since you are now putting some work and money into it.
/Kent
Now that you want to go over that, you should compensate with råsponten.
Personally, I would have rather gone the other way, that is, reduced the cc between the rafters, especially since you are now putting some work and money into it.
/Kent
It will be fine if you dimension it correctly! 
If you increase from 1.20 to 1.55, you increase the load on the roof truss by 30%.
This means you need to increase the bearing capacity of the roof truss if they are not already oversized.
I recall that the rule of thumb for raw plywood (at cc 120) is that 17 mm must be jointed over the truss and 22mm tongue and groove can be jointed anywhere.
Therefore, in your case, I would at least go with 22mm raw plywood and place all joints on top of the truss.
Those were my layman's opinions.
1 if strength is considered, 8 if you ignore it and just go for it.
(Even a woodshed roof probably hurts to get hit with )
If you increase from 1.20 to 1.55, you increase the load on the roof truss by 30%.
This means you need to increase the bearing capacity of the roof truss if they are not already oversized.
I recall that the rule of thumb for raw plywood (at cc 120) is that 17 mm must be jointed over the truss and 22mm tongue and groove can be jointed anywhere.
Therefore, in your case, I would at least go with 22mm raw plywood and place all joints on top of the truss.
Those were my layman's opinions.
1 if strength is considered, 8 if you ignore it and just go for it.
(Even a woodshed roof probably hurts to get hit with
)So the question is if I have oversized the roof trusses. They are 190 mm. Am I happy now?
Additionally, I plan to splice every other joint against a truss so that there is an overlap (2.10 + 3.90).
The plan looks like this:
Right now, the trusses rest on standing studs. Between the standing studs and the trusses, there is the wall plate. If I move the trusses to get cc 120, the trusses will be next to the standing studs. Is it enough to add an additional "layer" of wall plate so that the total thickness becomes 90 mm?
Additionally, I plan to splice every other joint against a truss so that there is an overlap (2.10 + 3.90).
The plan looks like this:
Right now, the trusses rest on standing studs. Between the standing studs and the trusses, there is the wall plate. If I move the trusses to get cc 120, the trusses will be next to the standing studs. Is it enough to add an additional "layer" of wall plate so that the total thickness becomes 90 mm?
The measurement of 190 sounds solid, but it doesn't really tell anything. It depends on the construction of the roof trusses and naturally how wide your wood shed is. But if it is a "normal" wood shed and "normal" roof trusses, it seems stable enough.zingo said:
So you have an existing frame with cc1550? Placing the trusses on the studs sounds logical. Alternatively, you could have a top plate of a standing stud, say 190, which you notch into the studs. A lot of work in retrospect. I would proceed with the roof trusses as you planned from the start. With 22 mm boarding, spliced over the trusses.
This cc measurement of 1200 is not divinely ordained as The Only Right Measurement. It probably came about more by chance. In Norway, for instance, they use cc 600 between trusses. They probably think we're very daring with cc 1200.
Oh, you already had the råspont. Yes, but go with slightly thicker bärläkt then, that should compensate.
Have you already gotten the roof tiles too? Or do you perhaps want them to be the same as on the house? Otherwise, you can get around the whole issue by choosing a lighter material for the roof; faux tiles of metal or Onduline, that black, corrugated cardboard. Suitable for a wood shed.
Have you already gotten the roof tiles too? Or do you perhaps want them to be the same as on the house? Otherwise, you can get around the whole issue by choosing a lighter material for the roof; faux tiles of metal or Onduline, that black, corrugated cardboard. Suitable for a wood shed.