Exposed Rafter Tails
Hi everyone,
My name is Derek. I’m in the midst of framing my house in northern Michigan. We are in a 60PSF ground snow load region. My plan, a craftsman-style cottage, features exposed rafter tails. The plans call for grooved plywood over the areas of the exposed overhangs at the gables and eaves to mimic t&g boards.
On the gable end, I have 2×6 outriggers at 48″ O.C. that extend through notches in the gable rafter back to the first common rafter with 3 16Ds at all junctions. I have yet to install the grooved plywood over the gable or eave overhangs.
In the meantime, two builders have stopped by to tell me I’m doing it wrong by having a break in roof sheathing at the gable and eave walls and that the gable overhang in particular will feel weak as a result.
An engineer has stamped and reviewed the plans. My concern is that maybe this is structurally fine, but will sag under a heavy snow, looking unsound. Has anyone done this detail or something similar in a high snow area? Don’t the outriggers provide enough strength to keep the gable overhang from sagging? Does the continuous 5/8″ sheathing really make the overhang that much stronger? Thanks!
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Replies
Derek,
How deep are the overhangs? Two easy ways to improve the strength are to decrease the spacing from 48" to 24", or run some of the grooved sheathing back to the next rafter.
Hi Malcolm,
16" at the eaves and gables.
Derek,
Would it change the look too much to make the spacing 24"?
Rocksteadily,
This may be too late (sounds like it's framed already?), but a very common detail we use where I am (southwest Montana, heavy snow loads) is to drop the outrigger rafters 3/4" (assuming 3/4" for the boards/eaves material). That lets you run your ply continuously. So the layup on the exterior is:
- Roofing
- Underlayment
- Roof Sheathing, nailed through eave boards directly into rafters
- 3/4" Boards, only on the exterior portions of roof / the parts with exposed rafter tails, laid across rafters and nailed
- Rafters, usually applied at the overhangs and run back past the main structural roof rafters
Paul,
A variation on that I use here where we have very low snow loads is to drop the overhangs 1 1/2", and use 2"x t&g, running a board back one rafter bay every two feet.
We regularly transition to tg boards at overhangs. The sheathing will add very little bending moment strength. As Malcolm suggested decrease your outrigger spacing if concerned.
Another option would be just take your tg look plywood back to your first rafter