# rafter birdsmouth and wall sheathing ???



## Clutchcargo (Mar 31, 2007)

Do you cut a rafter birds-mouth so that it sits on top plate including the wall sheathing (4" for a 2x4 wall with 1/2" CDX) or make the cut to the top plate and butt the sheathing up to the bottom of the birds-mouth? 
So sheath the wall first and then cut the rafters or cut the rafters first?
My house has the construction where the builders sheathed first and then cut the birds-mouth.


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## Scuba_Dave (Jan 16, 2009)

I usually sheath 1st, then do the rafters
Sheathing ties everything together so it won't move
On my cabana addition I did the bottom 3' with cement board then the rafters, then the rest of the sheathing
The old siding on the existing cabana rotted out at the bottom
So I used cement board on the bottom 3' to prevent rot


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## Joe Carola (Apr 14, 2006)

Clutchcargo said:


> Do you cut a rafter birds-mouth so that it sits on top plate including the wall sheathing (4" for a 2x4 wall with 1/2" CDX) or make the cut to the top plate and butt the sheathing up to the bottom of the birds-mouth?
> So sheath the wall first and then cut the rafters or cut the rafters first?
> My house has the construction where the builders sheathed first and then cut the birds-mouth.


Depends whether you sheath the walls first or after the walls are up. I sheath after the walls are up, so the birdsmouth is the width of the rafter.


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## Gary in WA (Mar 11, 2009)

So long as you tie the bottom top plate with the wall sheathing, for shear. If the rafter tails are left full thickness, as in a closed soffit, they may be in the way of that. Otherwise, you could add blocking across the top for shear-flow, a lot of extra work. Remember the nailing room required for the top of wall nailing if you sheath the roof overhangs first. Be safe, G


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## Wildie (Jul 23, 2008)

When I built my house I applied OSB sheeting to the frames before raising the wall. 
So I had to allow for both the rim thickness plus the OSB thickness.


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