Recommend me your technique for roof framing, to handle this. See the attached pic.
The pic is a plan view of a hip corner, with a 42″ overhang. Things aren’t quite to scale; I just threw this out to my truss guy and he came back with a layout somewhat different. My pic shows the jack nearest the corner closer than what he came back with.
Basically, the last hip jack truss, approaching the corner, is a little more than 26 inches from the corner, leaving the 2×6 subfascia to run close to 5′-8″ from the last hip jack to the tip of the doubled hip girder truss.
I know we have some stick work to do here, but what is best? We’ve a 4.5 pitch, and if I stickframe these corners with 2x8s, we can get a “beam” member to parallel the subfascia of 2×8, hung off the nearby jack truss and hip girder. It will be inboard the subfascia by maybe 6 inches. That would be a little better arrangement for hanging the outboard ends of the 2×8 jacks we’ll place. Hanging the jacks on that 2×6 subfascia makes me a little nervous.
What would you do?
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How much do you need to build up the plate to give you a birdsmouth?
If you add a couple 2x4 top plate to get you a birdsmouth? If so you can run your ceiling beams in first and then add the plates in between them.
If it's higher then that can you run the ceiling beams on first and put a plate on top and then cut a birdsmouth.
Do you have a cross section to show how high the HAP cut is on the truss?
Joe Carola
This way if you land on top of the ceiling beam.
Joe Carola
All well and good, guys, but what about when we get beyond the void, so to speak?
At a 42 overhang and 24 rafter spacing, we've got almost two full rafter spans that are out there in no-plate land.
I have two wall heights. One results in an HAP of 9 inches and the other is 12-1/8", so at my worst case of 12 plus, I need three 2x scabs atop my plate to get up to where a 2x8 jack will touch "plus," meaning I need to carve a little birdsmouth from it.
But beyond the corner, it don't matter. What do you do there?
One results in an HAP of 9 inches and the other is 12-1/8",
With those HAP numbers if you nail your 2x8 subfascia on first and nailing the outside corners together and then prop them up level and straight then you can use a 2x12 hip measuring 59-1/4" from the back of the 2x8 subfascia to the ouside corner of the building for your hip overhang and and a total hip length of 114 -7/8" if you marked a 4.5/17 plumbcut it would measure 11-7/8" if the 2x12 is 11-1/2".
Now your one HAP cut is 9" on the one wall so subtract 3/16" from 9" for your hip drop and come down from the top of your 11-7/8" hip plumbcut 8-13/16" and make your seatcut.. Drop the hip in place nailing it at the top where your double trusses are and at the back of your subfascia and birdsmouth. If you want plywood the inside of the trusses first so there's something solid behind the hip plumbcut just subtract the plywood thickness for your hip length.
You can do the same for your jacks using a 2x12 on the wall side with the 12-1/8" Truss HAP cut your plumbcut would be 11-9/16" just add another top plate or two.
On the wall side with the 9" Truss HAP cut you can use a 2x10 and your plumbcut would be 10-1/8" just measure down from there 9" for your HAP cut and layout the birdsmouth.
Once you set the subfascia, hip and jacks in place then you can frame in your level soffit with 2x8's. The 2x8 ledger up against the wall extend it all the way out to the back of the subfascia. Put diagonal braces going from the hip and jacks to the 2x8 ledger and put plywood gussets the same size as your overhang.
Joe Carola
Here's a couple suggestions.
Joe Carola
Why the difference in wall heights and how is the ceiling going to look on the inside?
With the difference in wall heights and HAP cuts are the trusses both 4.5/12 pitch?
Joe Carola
Attached is a drawing that shows how the wall heights and heels relate to each other.
The soffit is down low, at about the same elevation of the bottom of the 2x6 tails. Here is a pic of where we are going with this. We are reproducing this house from its plans. The client was able to buy the planset, and wants a version of this house for himself, one state away from where it was built originally.
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In this pic you can see how the boxdown soffits inside the house (which don't occur everywhere) are brought down to the level of the outside soffits.
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Support all of tha with cantilevered beams...Scribe once, cut once!
How 'bout this? From the last jack truss out to the corner, we'll double the subfascia, and use little 2x6 jacks to run out from the hip truss to the sub.
I'm not sure how much beef the soffit framing adds, but I am showing it here.
In my CAD model, the hip you see is a two-ply truss with each ply having a 2x6 top chord. Thus, the hip girder truss is projecting out there with a lot of beef, essentially a 4x6, and as you can see, the bottom chord is overhanging too, making the cantilever length less for the top chords.
I didn't model bevels on the hip girder end because I was lazy, but in the field we would cut them to provide nice wide nailer surface for the subfascia.
It is Cadkey 97, Pete. I work with it a lot, so it is easy for me to model things like this, but there are probably better packages now available.
The house I'll likely build next year is a copy of the one in the photographs in this thread. I have the whole thing modeled in 3D, with the detail all inserted where I need to have it (like the funky areas of cabinetry and built-ins). I use it to estimate, build, purchase, etc.