roof beam rafters vs trusses
roof beam rafters vs trusses
(OP)
Some installers only install roof trusses made of members.. they don't use wide flange beam rafters..
Is there some advantage of trusses instead of using I-beams such as W8x18? What are the advantage and disadvantage of each?






RE: roof beam rafters vs trusses
RE: roof beam rafters vs trusses
RE: roof beam rafters vs trusses
RE: roof beam rafters vs trusses
Ron... all our trusses are site constructed... we haven't got any ready made manufactured trusses.. first time to hear of this..
So between both site constructed trusses and site constructed wide flange rafters.. isn't it that the members of the trusses can bend in response to wind, whereas in wide flange.. it is often stiffer than the stress are transferred to the connections? Which is better.. stress in the members of trusses or stress in the connections of stiffer wide flange rafters?
RE: roof beam rafters vs trusses
BA
RE: roof beam rafters vs trusses
It's just cutting and welding angle bars. It could be done at site or at workplace but these are connected manually.. not done in a manufacturing plan welded by machine.
Some folks only make trusses.. so I wonder if these are really advantageous for roofing.. maybe the members in the trusses flexing and stretching in response to wind pressure is the main advantage of it?
RE: roof beam rafters vs trusses
Comparing these three systems:
1) A pitched roof truss with a flat bottom chord.
2) A pitched roof with rafters supported on a central ridge beam.
3) A pitched roof with rafters not supported on a central ridge beam.
In terms of material efficiency, which is not necessarily overall economy, I would say that #1 is the most efficient and #3 is the least efficient. That said, all of these systems are workable if engineered properly. And, for small spans considering economy only, the order may actually be reversed with #3 being the cheapest and #1 being the most expensive.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: roof beam rafters vs trusses
It's difficult to connect 2 wide flange at a pitch without any central ridge beam.. how do you detail the connections.. by simply cutting and welding the wide flange at an angle? Would this even be stable?
RE: roof beam rafters vs trusses
That's one way. I would normally include a full depth vertical stiffener at the joint. For lighter loads, this could be conveniently done using a bolted, end plate moment connection.
The beams would need to be restrained laterally by connection to a roof diaphragm of some sort, either using competent decking or discrete bracing members. The same would be true of trusses of course.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: roof beam rafters vs trusses
Can anyone see any problems with using rafter that is stronger than needed? For example.. using w8x18 or 8 inches x 5 inches by 18 weight for light roofing? This is just for additional safety and considering the prices don't vary much compare to lower sizes.. any complications of using stiffer rafter?
RE: roof beam rafters vs trusses
BA