I've built a patio cover onto the side of my house. Using asphalt
shingles. I have put flashing under the siding of the house. My
question is(I have rolled felt under the flashing on the patio cover),
do I nail a layer of shingles on top of the flashing, or just under?
To nail on top would pierce the flashing. The flashing does not lay
flush onto the patio cover and I dont like it exposed. What is the
appropriate course of action?
I am assuming a "shed roof" situation here. There should be a METAL flashing
tucked behind the siding and over the last course of shingles. Or over the
patio cover. Felt should have been the first layer. It should be under the
There are some things you can never flash properly when you use the wrong
materials for the job. I intend to tear off and not replace one of those
patio covers this Saturday. No, I did not install it. I am just going to
solve a long term problem.
Thanks for the reply. I have felted and shingled under the flashing.
I used a 1/12 pitch over 12'. Just curious about the flashing since
it doesnt lay flush against the patio cover. It is continuous
flashing. I've done everything correct, but since the flashing comes
manufactured with a 90 degree angle, it doesnt lay flush. Do I just
hammer it down onto the shingles? You dont cover this with a layer of
As "RicodJour" pointed out you can do a down turned bend to the flashing to
keep the yard side down against the shingles. People also cheat and use a
nail every 3 feet or so. On the farm we used lead head nails. Nowadays most
people just used a regular roofing nail and some silicone. Being some what
of an over builder, I were going to nail it down I would put a small dab of
roof cement under the tin at each point that I planned to nail and use the
silicone on the top side.
BTW I completely agree with the other posters who said 1/12 is to shallow.
If you never get wind driven rain from the yard side you may get away with
Thanks for the reply. Not sure what a "shed roof" is. I just have a
flat roof, almost perpindicular to the house. I have felted and
shingled under the flashing. I used a 1/12 pitch over 12'. Just
curious about the flashing since it doesnt lay flush against the patio
cover. It is continuous flashing. I've done everything correct, but
since the flashing comes manufactured with a 90 degree angle, it doesnt
lay flush. Do I just hammer it down onto the shingles? You dont cover
this with a layer of shingles somehow?
If you mean regular 3-tab or architectural shingles, a 1/12 pitch isn't
sufficient. You really need double coverage roll roofing (aka selvage)
on such a shallow roof, or better yet, an EPDM membrane.
If you covered the whole roof with something like Ice & Water Shield,
then covered it with the shingles, that would be far better, though I
believe your roof pitch would still be below the recommended minimum
The Ice & Water Shield is usually wrapped up the roof and onto the wall
sheathing, the roof is shingled and the metal flashing is on top of
everything. It is important to have the flashing conform to the slope
of the roof and be rigid enough to keep it from warping. You will not
be able to buy such flashing - it has to be bent up on a brake for each
job. The leading exposed edge is usually doubled back on itself -
~1/2" and bent under the body. This hem is far more rigid and presents
a nice straight edge.
In general, you don't nail into the flashing as each nail is a
potential leak, and if you're not careful with your choice of nails,
galvanic reaction from the contact of disimilar metals will eat away
the nail and flashing. The flashing should only project a couple or
three inches at the most. It's really just to cover that top edge of
the last row of shingles and hide the nails...in a normal roof. As
your roof is so shallow you will have to spend some extra time and
attention to make sure that is waterproof.
It might not be the advice you'd like to hear, but you should pull that
flashing and rework it. Unfortunately, even if you get that top
flashing and edge tight as a drum, the rest of your roof is going to
present problems. Regular shingles on felt roofing paper on a 1/12
pitch will leak.
Why did you ignore the instructions on the shingle wrappers?
I didnt ignore the instructions. First, let me say I'm in Texas, so
snow is not an issue, just rain. A one foot drop over twelve feet is
plenty according to instructions. When you say I need to rework the
flashing, what do you mean? I have not done anything I shouldnt yet.
I just didnt like the lay of the flashing and wondered if I should
leave it, hammer it down flush on the shingles, or if I could lay a
layer of shingles over it - which I thought would not work as I would
pierce the flashing. So tell me what you mean by "rework it" based on
what I've just said.
Sorry. Poor choice of words. Reworking flashing is hard to do and it
usually ends up looking like hell. Here's one way to do the flashing:
http://tinyurl.com/c9ule That shows a bend at the leading edge. I
like to do a hem, but they both work and keep that front edge straight
and tight to the roof.
I missed the begining of this thread, what brand and type of shingles
did you use?
Asphalt shingles shall in no case be used on roofs with less than 2:12
pitch and require special application on pitches less than 4:12.
Same thing on:
Essentially, they all say the same thing:
"Fiberglass or asphalt shingles are not permitted on roofs with a
pitch of less than 2:12. Less than 2:12 must be designed as a flat
I realize four of those links are from MN, but AFAIK, it is a fairly
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