Hi, I'm planning on building a house in near future. I want a vented attic with lots of continuous fluffy stuff(R60+) and framed rafters. Wondering if this design with possible modifications has any chance of getting approved by a professional?
The point of it, is raising the top plate for more insulation while countering the force of rafters pushing out.
Thank you for your opinion. Would replacing gussets with metal gang nail plates improve those chances? Or is it just so out of ordinary?
Jul 6, 24 3:05 pm ·
·
Non Sequitur
Wg, we’ve done this type of raised truss & plate reinforcement before but they were beasts (quad-ply flat truss cathedral roof with awkward bearing). It’s def not something your average truss framer can do.
Simon, either way you would need a licensed structural engineer to run calculations for you, and many who do residential work don't like thinking too far outside of their typical box. They consider not just the outward forces you are thinking about, but lateral/rolling forces, constructability, shrinkage (18" of cross-grain will move over time), etc.. You may get lucky; I work with one PE who is always willing to think creatively, though it always comes at a cost.
This is the correct answer. Even our structural engineering consultants don't design the trusses for their own projects. The truss supplier will have drafters and engineers who do this stuff in their sleep, including the required design for raised heels.
Having an stem wall isn't particularly new. I agree, hire a professional. I don't even want to waste my time with clients like this. They are just pain in the ass. Having a stem wall on top of the double top plate isn't new. That's basically platform construction. My house from 19th century does that same approach with balloon framing except the studs the same size continuous and not become 2x8 or 2x12 or whatever. Yeah, I could add in additional 2x6 or 2x12 framing under he rafters 1-2 feet inset and pack with insulation like crazy. Granted my roof is a basic rafter roof with 1x4 or 1x6 rafter ties. Trusses would be something I could use in a contemporary balloon frame house using 4x6 to 4x8 rafters. This would make for one hell of a wall, though and some stability over the height going up to about 16-20 ft. Depends on available length of wood. It is usually cut to certain lengths but you won't usually see logs longer than about 40-45 ft. length. 80 ft. is unusual. We rarely see lumber over 20 or so ft (or half common log length) for transportation on typical vehicles used by Home Depot and places to deliver the building materials to locations. They aren't usually the length of logging trucks. They are usually a tad more limited in length. Maybe 20-ft bed on a vehicle that's about 30-35 ft. in length. Would depend on the log trucks and they vary. Some are for transporting 16-20 ft. logs. Some for 30-40 ft. or so logs. So it depends.
In any case, the OP should consult a design professional. I do NOT want this person as client.
Thank you all for your input, I get a sense that it will be unlikely to find a professional willing to do this in our rural area. I wanted a rafter design because access to build site is tight winding dirt driveway, just going to need to knock down some more trees :( And I'll go with a truss package. I'm leaning towards a cantilever truss for 3' overhangs, lower exterior wall height than raised heel truss and still lots of room for insulation at the heel with high pitch roof. Once again, thank you all!
Higher Raised Heel Rafter Design
Hi, I'm planning on building a house in near future. I want a vented attic with lots of continuous fluffy stuff(R60+) and framed rafters. Wondering if this design with possible modifications has any chance of getting approved by a professional?
The point of it, is raising the top plate for more insulation while countering the force of rafters pushing out.
how about you hire and pay for a professional for their opinion?
I think I indicted that I will seek a professional, just wondering if this design is even possible. Simple yes or no opinion.
You’re asking for free advice from professionals. Raised heel trusses are typical, but not the way you’re showing them.
That is unlikely to be approved by an design professional or code official. It's a creative idea but the gusset strength is not easy to quantify.
Thank you for your opinion. Would replacing gussets with metal gang nail plates improve those chances? Or is it just so out of ordinary?
Wg, we’ve done this type of raised truss & plate reinforcement before but they were beasts (quad-ply flat truss cathedral roof with awkward bearing). It’s def not something your average truss framer can do.
Simon, either way you would need a licensed structural engineer to run calculations for you, and many who do residential work don't like thinking too far outside of their typical box. They consider not just the outward forces you are thinking about, but lateral/rolling forces, constructability, shrinkage (18" of cross-grain will move over time), etc.. You may get lucky; I work with one PE who is always willing to think creatively, though it always comes at a cost.
You just order the truss package from the truss mfr. Why make your life harder by trying to figure out their work?
Give them the specified dimension desired at the heel. They will engineer it & deliver them.
You still need a design pro to deal with whatever lateral may be involved in that structure in that location.
This is the correct answer. Even our structural engineering consultants don't design the trusses for their own projects. The truss supplier will have drafters and engineers who do this stuff in their sleep, including the required design for raised heels.
not my area of expertise, but just intuitively, but a pentagon cross section is going to defy the purpose of a truss I would think.
Just use a wood truss with an energy heel.
Having an stem wall isn't particularly new. I agree, hire a professional. I don't even want to waste my time with clients like this. They are just pain in the ass. Having a stem wall on top of the double top plate isn't new. That's basically platform construction. My house from 19th century does that same approach with balloon framing except the studs the same size continuous and not become 2x8 or 2x12 or whatever. Yeah, I could add in additional 2x6 or 2x12 framing under he rafters 1-2 feet inset and pack with insulation like crazy. Granted my roof is a basic rafter roof with 1x4 or 1x6 rafter ties. Trusses would be something I could use in a contemporary balloon frame house using 4x6 to 4x8 rafters. This would make for one hell of a wall, though and some stability over the height going up to about 16-20 ft. Depends on available length of wood. It is usually cut to certain lengths but you won't usually see logs longer than about 40-45 ft. length. 80 ft. is unusual. We rarely see lumber over 20 or so ft (or half common log length) for transportation on typical vehicles used by Home Depot and places to deliver the building materials to locations. They aren't usually the length of logging trucks. They are usually a tad more limited in length. Maybe 20-ft bed on a vehicle that's about 30-35 ft. in length. Would depend on the log trucks and they vary. Some are for transporting 16-20 ft. logs. Some for 30-40 ft. or so logs. So it depends.
In any case, the OP should consult a design professional. I do NOT want this person as client.
Thank you all for your input, I get a sense that it will be unlikely to find a professional willing to do this in our rural area. I wanted a rafter design because access to build site is tight winding dirt driveway, just going to need to knock down some more trees :( And I'll go with a truss package. I'm leaning towards a cantilever truss for 3' overhangs, lower exterior wall height than raised heel truss and still lots of room for insulation at the heel with high pitch roof. Once again, thank you all!
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