DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   Roofing/Siding (
-   -   Colliding slopes and midroof valley termination (

diyroofer 09-01-2011 01:59 PM

Colliding slopes and midroof valley termination
The first photo shows where the house and garage roofs meet, the opposite slopes overlap by about ten inches. As you can see, the overlap currently is unflashed and is not shingled, it has about 2-3 inches of underlayment exposed. During installation of the new roof, what is the best way to protect this overlap? I would guess that a piece of flashing extending up each slope 8-10 inches and extending 1" over each edge, would do the job? Any other suggestions?

Additionally, I have a double gable roof, one ridge running north south and one east west. The north south ridge hits the east west ridge in the middle. The valleys formed as a result of this intersection stop about 2.5 feet from the eave edge. I am wondering about the best way to terminate the valley flashing at the bottom of the valley? Also, I am going to tear the siding off the wall projection and re-flash/ you can see, it is sort of hobbled together as it is. There is a lot of this on the roof...see also the attached photo of the chimney...yikes. This chimney is now useless (services a gutted oil burning furnace in the crawlspace, and is in a terrible location for any future wood stove tie in) and will be coming down below roof level during installation of the new roof.

bcdemon 09-02-2011 07:27 AM

For the first pic you are absolutely correct. But I would go 12" up each side for better coverage, and your 1 inch overhang.

The second pic:
Terminating valley flashing? Just cut it along the gable edge (with a 1 inch overhang as well) and straght across the other side from there.

Also, when you shingle up to the dormer, try and bring your wall flashing right to the bottom of the valley aswell. As it is now the metal stops about 5 inches from the bottom of the valley.

And get rid of that chimney lol, what an eye sore.

diyroofer 09-02-2011 01:08 PM

Thanks for the information. The reason I asked about terminating the valley flashing: I was thinking about the way water will run down the valley (valley pitch is 4:12 and the total run is 19 feet), if I cut it straight across from the gable, the water be hitting the eave shingles at a 45 degree angle. It seems like it would have a good chance of getting pushed up underneath? Or is it not going to generate enough speed down that valley to flow under the eave shingles? There will definitely be I&W on the valleys and eaves, but I just want to avoid mistakes and I haven't seen much info on terminating flashing in a valley that ends mid-roof.

I am going to take the siding off the dormer and am planning on putting I&W up the wall 8-10" and out onto the eave, then follow with continuous "L" flashing to finish the horizontal run. The horizontal run ends where the back slope of the garage roof meets it. I was going to step flash this, and put the last piece of step on top of the "L" flashing that covers the horizontal run. The end of dormer you see in the original post is the end of the rake (right side) in the photo below. I assume I don't need to flash that little 2 foot valley that is formed there, would you agree?

I have a couple more questions about ventilation, but I will start a new post for that! Additionally, since we've touched on it in my last thread regarding ply over a couple pictures of the shiplap from the attic...what do you think?

The flex hose in that last picture is the outlet of the bathroom vent! It runs about 20 feet and vents out the blocking between the rafters, under the eave...i am going to vent that through the roof during the re-roof...I am pretty sure that will be more efficient than the way it is. Thanks again for the tips.

kwikfishron 09-02-2011 02:45 PM

199 Attachment(s)
You still need to step flash up that wall and I&W the valley too.

If you’re removing the siding be sure to install new felt on the wall over the top of your flashings.

diyroofer 09-02-2011 03:04 PM

Yes, I am going to step flash up the slanted portion of the wall, but was going to use a single solid piece of "L" flashing for the horizontal (not sloped, flat, whatever you want to call it) run and standard step flashing up the slope. I am planning on letting the last piece of step flashing lie on top of the end of the "L" flashing (where the sloped and horizontal portions of the wall meet). I was also planning on putting I&W along the wall behind the flashing and out onto the eave. Are you saying I should also put felt over the I&W on the wall and let the felt overlap the flashing?

That brings up another question. Do you recommend laying felt over the Ice and water shield on eaves and in valleys? Or starting the felt where the I&W ends (obviously I would overlap per manufacturers guidelines)? I have come across install instructions for some shingles that say if you use I&W at the eaves, then start the felt where the I&W ends, and I've seen other instructions (and suggestions in this forum) that specify putting the felt over the I&W right up to the drip edge (felt over drip edge at eave and under at rake).

So, which is "right"?

kwikfishron 09-02-2011 03:51 PM

199 Attachment(s)
Behind the siding there should be a weather barrier on the wall. That wb needs to lap over the top of the flashings so any water that’s gets behind the siding will shed over the flashing and away from the wall. If you’re removing the siding you might as well re-paper the wall with felt.

I’d run the felt over the I&W but I’m no roofer so don’t take my word for it.

Roofmaster417 09-02-2011 10:03 PM

1 Attachment(s)
The siding removal is in your favor for proper step flashing application.Obviously you know that the siding should be replaced after the roof installation.

But with no bigger than what the area is I would remove the siding during the tear off.That will assist you in a proper step flashing installation.

I keep my J-channel a couple inches off the roof deck.That will help the next roofer remove step flashing during a reroof/repair without damaging or removing the siding.

IMO its not a good idea to nail the step flashing to the roof deck and the wall.It creates damage to the siding when reroofing in the future.Only fasten the step to the roof deck.

As it was said run your flashing completely up both walls regardless of a pan across the saddle.

That picture of the chimney looks like a laborer from the previous roofing crew might be stuck under the roof by the looks of that lump.

diyroofer 09-05-2011 11:32 AM


Would you put ice & water and felt on the walls? I assume when you said flash all the way up both walls, you mean flash the entire length of the wall roof intersection, and not to literally run flashing all the way up the wall? I don't want to make too many assumptions though, so I figured I should ask.

Also, what is your opinion on ice and water on the eaves? Do you lay felt top the eave edge, over the ice and water, or start the felt where the i&w ends?

bcdemon 09-06-2011 08:19 AM

Felt over I&W:
Don't waste felt by laying it over top of I&W. Just overlap as required (4") and that will be fine.

Valley Flashing:
Your valley flashing will terminate on top of shingles, so any water that comes down that valley will exit onto shingles. And no, a 5/12 won't generate to much velocity.

"L" (Wall) flashing:
Run your L flashing about 5 inches past that little valley, mark where the top of the valley would meet the L flashing, and cut it upward from the middle bend on an angle from your mark. This is so it will bend up the other side of the valley. Then you put step flash over that. With your first piece of step flash, you'll want to hide that cut line, so drop it down past that cut line about an 1" or 1.5". You can caulk that cut line before installing step flash.

Exhaust fan vent:
Move that vent so it's just above the actual fan, and then shorten that hose.

Siding vapour barrier:
You need a vapour barrier under your siding. Usually "15 minute" building paper is all that is needed for siding. You will want to just overlap that onto your I&W. Although I have seen some guys bring it all the way down to overlap the flashings.

BCIDallas 09-08-2011 11:36 AM

insulation ?
as for ventilation, looks like the insulation goes all the way out over the soffits. . . is it by chance covering up any soffit vents? They need to be open to convect air flow.

diyroofer 09-08-2011 11:51 AM


The house has no soffits, the overhangs are open cornice type. Currently there is 2x6 blocking sitting on the top plates, between the rafters. Two of these pieces of blocking (there are 34 total) have been removed and replaced with 1/4" screen, these are the only intake vents for the entire attic. I am planning on adding intake vents into the blocking and installing ridge vent when I re-do the roof. I will then be sure the insulation is cleared from the behind the blocking, and I will install baffles between the rafters to assure air flows toward the ridge and doesn't blow the insulation around.

All times are GMT -5. The time now is 09:28 AM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1