Overbuild onto existing roof trusses
Overbuild onto existing roof trusses
(OP)
Hi, hope someone can help.
We are designing a project where we will be overbuilding new roof rafters over a portion of a garage that has engineered roof trusses at 24"o.c. The house is not that old, so I am assuming the trusses were designed for 30psf snow load/15psf dead. The new perpendicular gable roof will be a true rafter design with ceiling joist ties holding together 2x10 rafters except at the overbuild. We are providing a 14"LVL ridge board (not beam). The overbuild connection will sit on the existing sheathing of the trusses, and we will provide a flat 2x12. In theory, we are not adding any additional load to the trusses other than the dead load of the framing members. Will this be a problem? I do not have calcs form truss manufacturer. Perhaps add blocking to help the 2x12 flat span the 24" between the trusses
Thanks for any help.
We are designing a project where we will be overbuilding new roof rafters over a portion of a garage that has engineered roof trusses at 24"o.c. The house is not that old, so I am assuming the trusses were designed for 30psf snow load/15psf dead. The new perpendicular gable roof will be a true rafter design with ceiling joist ties holding together 2x10 rafters except at the overbuild. We are providing a 14"LVL ridge board (not beam). The overbuild connection will sit on the existing sheathing of the trusses, and we will provide a flat 2x12. In theory, we are not adding any additional load to the trusses other than the dead load of the framing members. Will this be a problem? I do not have calcs form truss manufacturer. Perhaps add blocking to help the 2x12 flat span the 24" between the trusses
Thanks for any help.





RE: Overbuild onto existing roof trusses
Mike McCann
MMC Engineering
RE: Overbuild onto existing roof trusses
Jay
RE: Overbuild onto existing roof trusses
RE: Overbuild onto existing roof trusses
In theory, the valley framing is supposed to be supported every 4' so the overframing load is evenly distributed over the trusses below. But I've never seen it done in practice.