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TGI Rafter framing

mrhodes's picture

O.k. I'm totally comfortable framing rafters out of regular lumber, but my question is how do you fasten these 11-7/8" TGI  to the top plate.  I'm under the impression that you're not supposed to cut the top or bottoms of them.   Does that leave the birds mouth out of the question?  If so, then what.    Thanks

(post #95489, reply #1 of 4)

Your TJ spec tech should have included this info on the drawing with the joist package. Typically they supply a cant strip ripped at the correct angle to fit the slope of the roof. Nail the cant onto the exterior edge of the wall plate, then nail through the bottom chord of the TJ into the cant strip. TJ blocking will be supplied for nailing at the plate edge.

One job we did last year had some common rafter TJs landing on a subfloor (shed roof tied in later). The spec called for them to be seat cut, and then web stiffeners supplied to be seat cut as well, nailed in through the web and then the whole assembly toe nailed to the subfloor.


Lignum est bonum.

Buccaneer Contracting

Penticton, BC

(post #95489, reply #2 of 4)

we are framing a house and the web stiffener option is specified:

1. cut rafter w/bird's mouth.

2. install on wall.

3. have a grunt like me come around and cut 1x6 parallelogram with one end cut off so the 1x6 fits snug directly above wall (2x6 here)

4. glue and staple web sitiffeners to both sides.

(different TJIs might need a different thickness material due to different flange widths)


(post #95489, reply #3 of 4)

I seem to recall an articale in FHB on this. Was it Jim Anderson or Jim at Great White??





(post #95489, reply #4 of 4)

GP has their details online at:,28,29.pdf

If you go to where you plan to buy the I-joists from, they should be able to give you a book that shows what details are and aren't allowed. But they all seem to be pretty similar.

OK, so what's the speed of dark?