Doing a new garage roof.
I noticed at Lowes that they have several different drip edges. Is
there supposed to be a different one for the rake than for the eaves?
Also, does the drip edge install right up against the sheathing? or
should there be a little bit of a gap. I have 5/8 sheathing and assume
standard 1" drip edge. The type F is the standard for eaves I think,
but this type B is a wrap around for the gable end from what I could
tell--kind of like a 90 degree wrap.
What is the standard practice?
Standard or preferred? Too many people skimp on the roof edging,
either omitting it entirely or using a poorly chosen profile. This
link shows some standard items:
The profiles that extend past the fascia by about 1/2" and with the
bottom edged kicked out are the best profiles to use at both rake and
eave. They're better for a bunch of reasons. The 90 degree bent edges
are poor substitutes.
Call a local roofing supply yard - they'll have a wider selection and
of better products than you'll find at a big box store.
The 10 year-old roof on my house has no drip edge on the eaves, but
the bottom layer of architectural asphalt shingles hangs over the eave
by about 1". The bottom edge just dangles over the gutter. There's
no snow here, only rain (Berkeley, CA). Is this a reasonable/adequate
practice? Would adding a drip edge underneath the bottom row of the
shingles be feasible/beneficial?
Yes. If the bottom of the drip edge is below the top of the gutter, then
you won't get wind blown rain behind the fascia. My house does not have
drip edge flashing and on a 2:12 pitch the water runs back under the
roofing and down behind the fascia.
I didn't install the roof and curse the SOB who did every time it rains.
Bob Morrison, PE, SE
R L Morrison Engineering Co
Ah, pitch, I should mention my roof is an 8:12 pitch (I believe), it
is just about the steepest I think is OK to walk on.
How is the drip edge normally attached to the roof deck? How can I
attach it to the roof deck when the first row of shingles is already
in place? The shingles are presumably only nailed at the midline, so
I should be able to lift the bottom half up to slide in a drip edge,
but I don't think there would be enough clearance to nail it.
8-in-12 is NOT okay to walk on (without a safety net). A 6 pitch is
even worse, because you don't think you even need a safety net. The DE
goes on first. Only tacked in a few places. Let it play straight. Then
the starter course is laid on top of the DE. Place your fasteners
through the starter course and into the DE. If you've already laid your
starter course and can still fit the DE under, good. The instructions
are on every bundle, by the way. Tom
Sorry, Mr. Whitney, I now realize that you aren't the OP. If the
starter course was fastened properly, you probably won't be able to
slip the DE up and under. But if you can, then all you'll need is a
fastener about every couple/few feet to secure it. Mind that they're
placed where they won't see any water from the course above. Tom
The problem with installing a factory drip-edge now, is the shingles won't
overhang the drip edge. Shingles should overhang drip-edge, 3/4" to 1".
I've seen my share of jobs, where water run back infiltrated and came in
through windows, because whomever installed the covering, ran starters &
btm. course flush with the drip.
A corrective action can be done, but unless you're willing to start from the
beginning, you have to compromise. To correct jobs like I explained, a 3"
strip can be cut and slid under the starter course, it must be off set so
butt ends are not aligned with starter. It is held in place with dabs of
Karnak, allowing a 1" exposed overhang. This creates a slight _hump_ at the
bottom, and may not be feasible for low pitched roofs.
The preferred method, is having a real roofer, which has a brake, custom
bend drip-edge from coil stock. You will not get the _F_ channel, but
instead an _L_ channel drip-edge. He can make the lips of the _L_, as long
as needed. Bends & reverse bends are placed to stiffen the drip-edge, with
a kick-out of 1/4" away from the fascia.
So the preferred ones from your link would be F-Styles: FA 1/2, F5 & FSN4
1/2? What would be your choice for a shingled roof with gutters? For a
tiled roof with no gutters, no fascia except 1x2 nailed on plywood edge?
Tile roofs are pretty scarce around here, and I've never worked on one.
I'm not sure if the roof edge requirements are different for them.
The F 4 1/2 is a good all around choice. The only time that the
gutters would come into play is if the fascia was narrow and the gutter
guy went with a simple way of hanging them. The height that a gutter
is supposed to be held down from the extended plane of the shingles is
dependent on the slope and your local conditions. It's held down
mainly to allow snow and ice to slide off, so that may not be a concern
where you are.
IMHO, they should outlaw the B channel. Water will follow that bend right
back into the fascia. Again, IMHO, B channel is made for those who want to
take a short cut at your expense. They don't like trimming edges of
existing shingles, so they cover them up, which creates problems which
aren't noticed until they're long gone.
Whatever roof edging you choose, the bottom edge should have a kicked
out lip. That makes the water drip free from the fascia instead of
running down it, prevents capillary action from pulling water up under
a flush piece of edging, and, most important, makes it easy to repaint.
The tip of the brush will run up behind that kicked out lip and there
won't be any exposed edge-of-paint-film. Makes cutting in a snap.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.