See attached photos. Garage is 1955 build. We’re removing the ceiling joists and installing rafter ties above to “vault” the ceiling. I’m concerned that there isn’t enough rafter bearing on the top plate, because they didn’t cut a birdsmouth to attach the rafters to the top plate.
To address this, I’m going to sister the existing 2×4 walls with 2×6, then add a ripped 2×4 on end to the side of the top and bottom plates. This will essentially turn this into a 2×6 wall, thereby adding another 2″ of bearing for the rafter.
How else can I improve the joint at this location? If I add hurricane ties like Simpson H1, will all of the nails compromise the little bearing wood that I do have?
Thanks in advance for your help.
P.S. We intend to sheetrock, tape, and paint the walls and ceiling after vaulting.
Replies
That’s one of those things you see and are amazed by how long it lasted. Your idea for the wall makes sense. You could also sister the rafters and add a birdsmouth to the sister piece. This could be full length or just a few feet at the end.
Yeah, this house is in Connecticut and there has been huge amounts of snow on this roof with no issue to date.
I'm just concerned that the ceiling joists fastened to the side of the rafter are adding some bearing capacity for the rafter; and when I remove them to vault the ceiling, I could have issues.
How could I sister the rafters and add a birdsmouth? Typically the angle of the rafter (relative to the wall) is such that the top of the rafter extends past the wall, and the birdsmouth is in the bottom of the rafter.
As you can see from the pictures, that wouldn't be possible here because the roof sheathing is in the way.
Add your 2x ledger to the face of the top plates, bird’s mouth buts into it. You could make this piece be like 2’ long with a level cut on top and your collar tie can sit on top of it. And yes taking out the ceiling weakens the structure since there is no bottom leg of the roof gable triangle it makes the walls want to go outward so put the collar ties as low as possible. Hot tip leave a couple of the ceiling joists in place, hang drywall at the top of the ceiling then install the collar ties since once they are up it’s hard to get full sheets of drywall past them.
This is an awesome idea. Thank you!! Any idea what size nails and nail pattern would work for this sistering?
How many nails and nail pattern depends on how long the sister piece is. In reality this piece really doesn't have that much weight on it. If it is 2' long I'd probably shoot 3 pairs of nails in it with my nail gun, or drive 6 10 penny nails, or drive 6 structural screws. The real hero in this assembly will be the ledger you screw to the top plate (black X in the drawing). This guy increases the width of the top plate so all the weight isn't on the tip of the rafter so it should be secured well. But if you're putting 2x on the flat or 2x2's below it those help take the load too. The sister piece will make the rafter to top plate connection stronger but it is also a nailer for the bottom edge of the ceiling drywall.
Be sure not to skimp on the collar ties. Personally I like to just use a 1/2" nut and bolt through the rafter and collar tie instead of blasting the end of the collar tie with 4 nails. They can be 1x. A painted or stained 1x6 can look pretty nice. Align them to work with a drywall seam so you just notch the end of 1 piece of drywall. Below is a stained 1x6 collar tie on an attic conversion I did. Good luck