I am a goofy framer. I’m faced wiith a california style valley to cut. It is an 8/12 onto a 10/12. the first valley jack will be upwards of nineteen feet long. Sucessive rafters decrease in length by about three feet at a time.
Has any one ever used I -joists in this application. Being as it’s here in Colorado there will be Snow load (when the drought ends) and also we are in an eighty mile an hour wind zone.
thanks for your opinions and warnings.
jim
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Replies
Just wanted to clarify the rafter shape. They will be cut with an 8/12 plumb cut on the top and an 8/12 level cut beveled forty degrees to fit onto a 3/4" valley board on the plane of the 10/12 roof.
thanks again
jim
Keeping in mind that I have never used I joists in a roof....here goes.... provided the i joists are spec'ed to handle the load....I would use a 2x valley cleat. I joists meeting ridge will need special hangers available through your manufacturer and must be installed before the roof sheathing in most cases. Make sure your valley cleat is deep enough to "catch" the bottom flange of the I joist for proper bearing. Hope this helps.
Couple of things come to mind.
First is that I doubt the I-joist manufacturers would go for it. I-joists are supposed to be supported on the bottom flange. You'd have to use a valley board that's something like 16" wide to be able to do that.
Second is that they're supposed to have a ridge beam to hold up the top end - Not just a ridge board. And you'd have to get special hangers to attach the I-joists to the ridge beam, as well as some straps over the ridge. And you'd have to have something designed to hold up the ridge beam.
Guess none of the above arguements are a huge deal, but they all could be used against you by a home inspector or building department.
Whya re you thinking about doing this? Is it because they're straighter? If it is, try using smaller sized lumber and blocking it down to the roof below. (Actually, you're supposed to do that anyway, but nobody does that I know of)
My kid beat up your honor student.
Boss
I was thinking of using a 11 7/8" ml for ridge beam posted to bearing wall below. I-joists because of the length. I've done a few roofs using I-joists so I know about the stupid butterfly hangers. Never have cut them as valley fill though,16" valley board could be handled by using two widths of 1x 10. I think I'll just use dimensional and block as you reminded us to.
Thanks Jim
Dont do it Jim ,way to much work in the extra blocking you must do at the bearing and connection points . I-joists are fine in a horizontal plane , but start to tip them and you get a whole host of issues you must deal with.
They still grow trees long enough and straight enough for 20'
When we here in BC canada are "forced to use" I joists for rafters, the manufacturer reps and the building inspectors require us to solid block all bearing points. We use a combination of ply and dimensional wood to fill the web space for 12 inches and flush to the edge of top and bottem cord, and lots of nails or screws. This is very time consuming but structurally logical. It does help eliminate any brain work in hanger connections as the I joist now resembles a piece of dimensional lumber. In short, too much work! If you do decide to use the I joists, have fun cutting and supporting a birds mouth.