flashing a porch roof on the gable side
wvjack
| Posted in Construction Techniques on
I’m completing a wrap around porch on my home. All is going well on the eaves side of the house. The problem is how do I flash the gable side. I have t-111 siding on the house now. I have read somewhere that you could cut a shallow kerf for the flashing, but that doesn’t seem practical, since the siding is only 1/2 inch to begin with. Any ideas?
Thanks.
Replies
You have a difficult sitruation since the siding and sheathing are one and the same with T-1-11. You need to run the flashing up the wall four inches, placing a bead of high quality caulk behind the metal.
Then make a piece of 1x6 with the top edge beveled off to shunt water away from the wall. hold it in p;lalce and pencil a line where the top will be, or measure and chaulk line it if it is a long span. Run another good bead of caulk just below the line, and nail the 1x6 to the line. you now have a double bead to trust.
but since the T 1-11 has those darn gooves dadoed into it, you now need to caulk the tiop edge enough to be sure that those are not going to pocket any water.
This will tiotally depend on the caulk so use the best, and be sure the paint job is not flaking away or dirty. odds are that it will do fairly well for five to ten years. by then, maybe you can afford some real siding.
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Thanks for the advice. This needs to last a couple of years, until we have the money for the log siding.
You have several options, I'll run one by you:
Snap and saw a line 6" above the roofing of the porch along the siding. Check your blade depth! Just cut through the t-111 and not anything behind. Remove this strip, you may have to cut along tight to the roof depending on how you ran the sheathing.
Tuck z-flash, either bent yourself or purchased with the top inner flange up behind the t-111. Caulk any opened joints in the t-111 but not the bottom, if water gets in you want it to flow out over the flashing. It is worth noting that it is best to try and get the z-flashing flange behind any housewrap or builder's felt behind the t-111.
Install sill flashing along the roofing as usual, I would add as wide a strip of ice& water shield or the like first then the metal.
Install a 1x6 trim board in the gap, tucked up tight to the z-flash. A bead of caulk along the top to seal under the z-flash is ok but not the bottom. The trim piece could be whatever matches, cedar, painted wood, Pvc/Azek, whatever. Backprime and prime all cuts. If that side gets the wind, use trim screws so that you can pop it out and troubleshoot any problems. Stainless would be best and you won't need many so that it shouldn't too expensive.
You will end up with a quarter or half inch gap between the trim board and the roofing. You can paint the flashing black or the trim color to disguise this prior to installing the trimboard. You could use a wider board but when fit too tight, a scribed board tends to trap water and debris plus it gets and stays wetter. A fine detail but that's up to you.
That's the long version. The short version is trim the siding up an inch and tuck the sill flashing behind. This is a royal pain and if you get it wrong you may not know until snow piles up and melts. The trim board allows you to get the flashing in easier and better and gives you an access point to deal with any problems. Take it from there.