Roof Sheathing Overhanging Fascia
Should Roof sheathing not overhang fascia? Why not?
I’m not a roofer, though I have roofed. I found the drip-edge/fascia area to be a confounding area. Fascia is a very common item to see rotting. Don’t use a wood fascia, is one path forward.
Tom from this old house is a big proponent of gapping the drip edge off the fascia to break the tension and keep the drip line further away from the fascia. I seldom see this done, though it makes sense to me when possible. Mechanically, some drip edges are hard to do this with (on steep pitched roofs).
I also see many articles and videos say “make sure you don’t overhang the fascia [with the sheathing].”
But if we are going to put a drip edge and give it a slight gap, wouldn’t that extra bit of sheathing not only NOT be in the way, but add support to what would otherwise be thin metal? Just wrap you Ice & Water over the ply onto the tippity top of the fascia.
I am in the land of steep pitch roofs, so keep that in mind (most drip edges don’t seem made for steep pitch roofs because they are bent close to 90! wth)
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Replies
maine_tyler,
Drip-edge should be formed for the specific roof pitch it will be used on. You don't want to use the generic stuff at the big box stores. Apart from the problems with differing pitches, they also have too small an overhang . If it is sufficient (1 1/2"), I don't see any reason to gap the vertical leg from the fascia.
It's definitely possible to have one fabricated that rather than return and then go down the face of the fascia instead had a thickened edge to wrap around a sheathing overhang.
When possible, I prefer to locate the top of the fascia flush with the top of the roof sheathing and extend the ice + water shield over the top of the fascia. That's not always possible or practical but I think it's the best way to protect the fascia.
The main issues I see with extending the sheathing over the fascia are getting the fascia straight (if the subfascia isn't perfect) and risking being able to see the edge of the sheathing if the dripedge is of the lumberyard variety and held off the fascia a bit. I think it makes sense to gap the dripedge, and last year I heard building scientist John Straube say it's important, to prevent water from wicking back to the fascia.
I agree with Malcolm that ideally the dripedge would be custom-formed but I have rarely seen or done that in Maine, even on fairly high-end projects. If you have access to a brake or someone with a brake, that would be the best, and again according to Straube, make the vertical leg as tall as you can and make the kickout at least 1/2" long.