TJI Floor Joist/ Wood Rafter Connection
TJI Floor Joist/ Wood Rafter Connection
(OP)
need some help with this. my engineer is not that good with nails
I came up with 785 lbs per rafter for the thrust. please correct me if wrong. Need some strap etc for this, do not want to rely soley on the plate on the floor.
the span of the Bldg is 27' inside, clear spanning the whole thing
the roof pitch is 10/12
rafters are 2x10
TJI is 16" 560...the flange is practially a 2x4
I tried to attach a dwg, but if not visible, the problem here is the
rafter sits on top of the plywood floor on a plate, as i can't notch the TJI floor joist
I came up with 785 lbs per rafter for the thrust. please correct me if wrong. Need some strap etc for this, do not want to rely soley on the plate on the floor.
the span of the Bldg is 27' inside, clear spanning the whole thing
the roof pitch is 10/12
rafters are 2x10
TJI is 16" 560...the flange is practially a 2x4
I tried to attach a dwg, but if not visible, the problem here is the
rafter sits on top of the plywood floor on a plate, as i can't notch the TJI floor joist






RE: TJI Floor Joist/ Wood Rafter Connection
Other than that, the detail is a good one. I have used that same exact framing scheme on several homes.
I'm not sure why you'd want to notch the floor joists anyway.
The floor joists should function as a collar tie and with the 2x6 plate resting on the rim board & plywood diaphragm you should have a very stiff system.
Only questionable thing is relying on toe nails in the rafters.
One option there would be to place 2x6 blocking in between each rafter directly on top of the 2x6 sole plate so you can nail at 90 degrees, but I still think a clip of some sort would be easier.
RE: TJI Floor Joist/ Wood Rafter Connection
You want to cut the joists to match the roof pitch and rest the rafters on the wall below.
I believe you can do this but the manufacturer of the joist will require that you put blocking in the webs of the joists to compensate for cutting the top flange.
RE: TJI Floor Joist/ Wood Rafter Connection
If you go with the "blocking" idea of my last post, you probably only need a block every-other rafter space with two rafters being nailed to each block.
MSquared....where you at? This is right up your alley, no?
RE: TJI Floor Joist/ Wood Rafter Connection
sent me a detail as such...my concern is the rafter connection.
Simpson told me to use an A35 which just connects to the plate, and if the plate fails.....
RE: TJI Floor Joist/ Wood Rafter Connection
And thanks for the comments so far!
RE: TJI Floor Joist/ Wood Rafter Connection
I have seen details for cutting the joists as you describe. I have used the detail in the field. Must have been a different manufacturer.
RE: TJI Floor Joist/ Wood Rafter Connection
And as Toad said, you will need some type of strap or other connection to tie the roof rafter back into the floor joist to act as a collar tie or bottom chord.
RE: TJI Floor Joist/ Wood Rafter Connection
BA
RE: TJI Floor Joist/ Wood Rafter Connection
at the heel connection. There are also collar ties.( i know don't do much, but some)
I upped the plate to 2x8 with a row of 3 nails @ 4" o.c. with blocking below and a simpson A35. Nailing the plywood in the eaves at 4" o.c.
We are just going to have to see what happens....
RE: TJI Floor Joist/ Wood Rafter Connection
"I upped the plate to 2x8 with a row of 3 nails @ 4" o.c. with blocking below and a simpson A35. Nailing the plywood in the eaves at 4" o.c.
We are just going to have to see what happens.... "
RE: TJI Floor Joist/ Wood Rafter Connection
Simpson does make twist straps to cover this situation. One or twoo at each joist should develop the necessary tension into the floor joist. Place the twist straps on top of the 3/4 ply and nail off to the rafters. You will need to place the straps before you place the top plate and rafters, but it can be done.
As mentioned above though, if you are not a structural engineer, and considering the fact that if it is not designed correctly, you will have a serious structural problem, I insist you engage a structural engineer to properly size and detail the connection.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: TJI Floor Joist/ Wood Rafter Connection
thanks for all the helpful comments.
RE: TJI Floor Joist/ Wood Rafter Connection
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: TJI Floor Joist/ Wood Rafter Connection
"Just sick Toad... You don't want to get this cr#$...
What?
RE: TJI Floor Joist/ Wood Rafter Connection
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: TJI Floor Joist/ Wood Rafter Connection
I thought I ticked you off somehow.
RE: TJI Floor Joist/ Wood Rafter Connection
My son and grandkids have had this stuff for two weeks now and they are just on the downhill side of the curve. Diane and I have only had it for about a week. Saps all your energy and leaves you mentally drained.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: TJI Floor Joist/ Wood Rafter Connection
Honest to goodness, same thing here.
My two yr daughter has been a damn mess, in and out of the doctors, now I'm feeling it pretty good too. Miserable. It's been weeks now.
RE: TJI Floor Joist/ Wood Rafter Connection
RE: TJI Floor Joist/ Wood Rafter Connection
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: TJI Floor Joist/ Wood Rafter Connection
at any rate we have a design i have confidence in,
RE: TJI Floor Joist/ Wood Rafter Connection
The horizontal thrust is 12/10 times as much or 0.6wL.
The axial force in the rafter is (10^2 + 12^2)^0.5/10 = 1.56 times as much or 0.78wL.
BA
RE: TJI Floor Joist/ Wood Rafter Connection
BA
RE: TJI Floor Joist/ Wood Rafter Connection
I think the rafter reaction on the wall is .5wL, and the axial load on the rafter is .78wL, but the rafter thrust is .3wL.
Assuming the OP'er. can put the 2x10 rafters on the 3/4" plywd. right over the TJI's, the 2x6 sill pl. on top of the plywd. may not be req'rd., or maybe should be standing on edge btwn. the rafters, as blocking. He may want squash blocks at the webs of the TJI's. Then use a concealed flange joist hanger (Simpson, LUC26Z or USP, JL26IF-TZ) laying horiz. on top of the plywd. to pick up the thrust, nailing through the plywd. and the top flg. of the TJI, and the rim board. Cut the rafter seat cut, then over cut the plumb cut enough to receive the bearing seat of joist hanger (B = 1.75 - 1.875") above the rafter seat, just a saw kerf.
RE: TJI Floor Joist/ Wood Rafter Connection
strong enough to nail into from above to help hold the plate down.
RE: TJI Floor Joist/ Wood Rafter Connection
You are correct, as usual.
BA
RE: TJI Floor Joist/ Wood Rafter Connection
I'm getting slightly different values for the vertical and thrust reactions...probably rounding.