For mine I just tied across the joint of the upper pitch with a level ceiling. Notice the length og gusset BL is 3/4 the length of L1. I haven't studied the paper deeply, it looks interesting once I convert to measurements I can wrap my head around. You're not proposing quite doubling the size but there's a concept I see most folks miss. 2 times the load and 2 times the breaker bar length. the torque on those rafters and joints, would quadruple. Remember when using that kind of logic that if your new span is about double, the load is going to double AND the lever arm is twice as long. The truss has not sagged a bit, nor have the walls bowed out at all. QuoteThat said, by my calculation, there is about 3500lbs of snow on the roof right now and it has seen much more than that over the last 20 years. I'd be interested to hear thoughts from others who have built similar trusses or have more design knowledge than I do. I was also able to find a paper online detailing the construction of these kinds of trusses and it doesn't seem to mention collar ties-just gussets: Plus, the loft will only occupy about half of the building-the other half will be open to the ceiling. The floor joists for the loft (I plan on using 2 x 12 x 20) will serve to hold the walls together, but I plan on putting that in later as funds are available. I suppose I could add a collar tie near the top, but then I start to lose headroom. The biggest concern is that the truss will transfer too much horizontal force to the walls, pushing them out. The gussets would extend 18" out from each joint. The plan would be to use 2 x 6 x 8s for the rafters (using a traditional gambrel design each rafter would be about 7'-8") joined together with 1/2" plywood gussets, glued and nailed on each side. I am hoping that I can use this design to create a large overhead space for a storage loft on top of a 20' x 24' pole barn frame. That said, by my calculation, there is about 3500lbs of snow on the roof right now and it has seen much more than that over the last 20 years. The gusset plates are also small, and they are stapled on. They are gusseted on both sides, but are not glued as far as I can tell. The span is 14' and the trusses are spaced 24" OC-they are toenailed into the top plates of the walls. The truss consists of 2 x 4 rafters joined together with 1/2" plywood gussets. My father has a stick built shed on his property with a gambrel roof. What I'm trying to figure out is whether or not I can scale up a simple gambrel truss (more like an arch) that I've seen used in smaller buildings. I am planning a small pole barn (20' x 24') and I'd like to incorporate a gambrel roof in order to accommodate a good sized storage loft.
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