Pitch(es) for roof against headwall and sidewall?
I’ve have a small, open porch off a side entry door. The porch is 7′ deep x 6′ wide. It’s located in a corner. So, as you stand on the porch and face the entry door, there’s also a wall immediately at your left.
The roof of this porch was destroyed by rot. Water from the main house roof above, from a valley, poured onto it for years. I’m replacing the entire porch roof and its rafters.
My question is, besides recreating the 5/12 pitch of the roof, down from the headwall above the doorway, should I also make this roof have any pitch at all in coming away from the sidewall it adjoins, also? My thought was if I pitched it slightly upward with respect to that sidewall, it would make water on the roof move toward the valley of the step flashing, which would then keep it moving downward toward the kick flashing and gutter at the bottom.
Or do I just keep this roof perfectly perpendicular to the sidewall or even pitched slightly downward from it, to keep surface water moving away from the sidewall? I wanted to say yes, but then I thought that if any water did ever get past the step flashing, then it would want to go the rest of the way down under the shingles, deck, etc.
I’m sure someone here already knows for sure the way it should be done so I want to just ask, thanks much! ?
Replies
A picture tells the story.
Here's a couple of photos of this porch. The question is, besides the obvious 5/12 pitch of this small porch roof, should I also tip it sideways a little (when I build a replacement roof - the one in the pictures is totally removed now)? As in, should I tip it a little toward its sidewall, or tip it a little the other way, so water would run at a slight angle away from the sidewall as it's running down the roof pitch toward its bottom edge?
If it’s flashed properly it should not be a problem. Also, make sure there is a decent gap where siding meets the roof, so you will see about 1 1/2” of exposed flashing. The flashing should go over the first course of siding to prevent water from getting into the wall. It would not hurt to lower the post corner just a bit to encourage drainage away, but don’t get too extreme with it or it will look noticeable. Also, installing a valley overflow protector on valley above will help. Need to make sure gutters are working properly and are clear as well. If the gutters cannot keep up with most rains, you may want to consider bigger gutters.
It looks as if the old roof failed because of the pounding waterfall that landed in one place from the valley above, overflowing the gutter. Start by improving that situation, possibly with a deeper gutter. If this gutter isn't likely to get cleaned regularly a screen to keep out debris would be worthwhile.
I wouldn't worry about changing the pitch of the porch roof since that didn't contribute to the problem. But definitely put down a good peel and stick membrane on the whole porch roof before you shingle it. Sounds like you already know the details for flashing a sidewall, especially the kick out.
Thanks for the replies!! I did fix the problem with the gutter above the roof. It had sagged right at the bottom of the valley above it. Water remained standing in it all the time, and slowly leaked/dripped down out of it onto the roof below, that failed. Like Chinese water torture. The gutter and downspout were also completely filled up with dirt and leaf matter. Whenever it rained it was like there just wasn't any gutter there at all, is what it amounted to.
Now that I've cleaned everything out, and redone the gutter hangers so that it drains, maybe I'll put a hardware cloth barrier over it, to keep the leaves out. That should work, yes? I know there's products you can buy that are more finished looking but this isn't in a very visible location from anywhere so I'm thinking 1/4" hardware cloth would be fine. Maybe stainless steel type.
For the new roof, it sounds like just the regular pitch of the roof is the 'normal' thing to do, not also compound it with a bit of tilt toward or away from the sidewall it adjoins. I'm just trying to keep in mind the 'think like a raindrop' mantra a cherished friend passed along to me, decades ago. I will definitely make sure I get the correct materials and way to configure them for the flashing, and water barrier underneath it. Covering the whole roof with a water barrier membrane of some kind under the shingles sounds good to me. I'll check back in here for more advice when I get that far. I really appreciate it, thanks!
-John
Most hardware cloth openings are too large to be effective as gutter guards for long. Twigs, needles and small leaves will work its way through the openings. The rough surface will also catch debris.
Need something with a smooth surface and openings no bigger than 1/8" inch or so,
Something like the Ply-Gem Leaf Relief (Alu-Rex T-Rex in Canada) continuous hanger works well. There are similar designs for use with existing hangers.
The porch roof is pitched well enough that any compound pitch added would not likely make much difference. On a longer roof or a low pitch it could make sense. I've worked on large flat roofs and in that situation you can buy tapered underlayment to help guide water away from walls. Just be really careful with the kickout so the water is clear of the siding when it leaves the roof.