A question for those in the know:
The plan is to build a garage with a span of 8.3 meters, 15-degree roof pitch. Is it sufficient to use self-supporting trusses with the dimension 45x170 on the upper and lower chords, 45x145 on the diagonals? Otherwise, opinions on what should be used are welcome... Thanks!
The plan is to build a garage with a span of 8.3 meters, 15-degree roof pitch. Is it sufficient to use self-supporting trusses with the dimension 45x170 on the upper and lower chords, 45x145 on the diagonals? Otherwise, opinions on what should be used are welcome... Thanks!
The load-bearing capacity depends on whether it's a single-slope roof (shed roof) or a pitched roof with a slope from the ridge of 14 degrees in both directions. For a shed roof, beams on supports, trusses, or some form of box beam, etc., are used. For a pitched roof, a free-standing truss construction can be used.
You haven't mentioned how long the garage is going to be?
If it is not too long and single-sloped, I suggest instead placing a beam 'in the middle' and arranging the 'trusses' as a floor system. This is the simplest way to arrange the load-bearing even if the beam encroaches somewhat on the height of the garage.
The alternative is to build beams with webs of 12-15 K-plywood and flanges of 28x70 or 28x95 p.b.s. at the top and bottom. Such a construction becomes stronger than a truss of the model you describe. Easier to make, but a bit more expensive. The 'web' needs to be a maximum of 60 cm high, depending on the snow zone you are building in. You may also need, (considering that K-plywood is not made in longer lengths than 3-3.5 meters) two to three layers of these to be able to splice them. And of course, it requires loads of wood glue in between to handle the shear forces.
You (or your designer) will find all the necessary strength values and formulas for calculating such beams in the Swedish National Board of Housing, Building, and Planning's Construction Regulations, section 5.
It is even more clearly illustrated in the previous Swedish Building Code 1980 (1983:2), section 27:333.
If it's a pitched roof, you need to make more detailed calculations and take into account the snow zone and wind, as well as what you intend to put on the roof (metal, felt, concrete tiles). Here as well, it’s possible to build the truss with webs of K-plywood instead of a truss. However, since the ridge height would be up to a meter, a considerable amount of K-plywood is needed.
______________
Builder
You haven't mentioned how long the garage is going to be?
If it is not too long and single-sloped, I suggest instead placing a beam 'in the middle' and arranging the 'trusses' as a floor system. This is the simplest way to arrange the load-bearing even if the beam encroaches somewhat on the height of the garage.
The alternative is to build beams with webs of 12-15 K-plywood and flanges of 28x70 or 28x95 p.b.s. at the top and bottom. Such a construction becomes stronger than a truss of the model you describe. Easier to make, but a bit more expensive. The 'web' needs to be a maximum of 60 cm high, depending on the snow zone you are building in. You may also need, (considering that K-plywood is not made in longer lengths than 3-3.5 meters) two to three layers of these to be able to splice them. And of course, it requires loads of wood glue in between to handle the shear forces.
You (or your designer) will find all the necessary strength values and formulas for calculating such beams in the Swedish National Board of Housing, Building, and Planning's Construction Regulations, section 5.
It is even more clearly illustrated in the previous Swedish Building Code 1980 (1983:2), section 27:333.
If it's a pitched roof, you need to make more detailed calculations and take into account the snow zone and wind, as well as what you intend to put on the roof (metal, felt, concrete tiles). Here as well, it’s possible to build the truss with webs of K-plywood instead of a truss. However, since the ridge height would be up to a meter, a considerable amount of K-plywood is needed.
______________
Builder
45x195 K24 in the upper frame 45x145 K24 in the lower frame 45x120 K12 middle post in the ridge, wedges where the upper and lower frames meet
then it is important to choose the right nail plates and nail in the right place
then it is important to choose the right nail plates and nail in the right place
