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Questions about where walls/eaves meet the roof (like dormers)

Questions about where walls/eaves meet the roof (like dormers)


  #1  
Old 10-09-14, 04:43 AM
J
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Questions about where walls/eaves meet the roof (like dormers)

Hey Guys,

So I'm in a race to beat the rain one again. The problem I'm facing right now is with the eaves and walls from the roof that overhang on the main roof. What I have is two 'dormer' type rooms that jut out of the house perpendicular to the rest of the roof. These two rooms have overhangs that extend over the main roof. Here's a picture:



Problem 1 was the gutters. I'm no gutter expert, but I think (at least on the dormer rooms) they took shortcuts rather than doing them the right way. The gutters that collect the water from the roofs of the rooms guid the water back to the main roof and down. They just gut a hole in the end of the gutter and butted it up against the roof. Well, they did that all the way around the house, and I already had another one leak over my garage...probably from water damming. Is that a typical way of installing gutters, or should I add some full downspouts or at least down spouts that feed directly into the other gutter that lines the main roof?

Problem 2 is waterproofing under the overhangs. Since both overhangs showed water damage leaking down the adjoining walls, I want to make sure this is done right.

I've redone the valleys where the butt of the dormers meet the ridge of the main roof. I've added 2 sheets of 30# paper in each valley, and put some 14" flashing under this in some of the area (because there's a gap where the sheathing from the extension meets the sheathing from the main roof where water could easily get in (probably 1/8". Now the overhangs have fascia on them where they meet the ends of the valleys. I installed drip edge to about 1" away from the valley, but didn't think that was enough. So, I bent some flashing to but up against the house, and then got a longer piece of flashing that extends under the end of the valley to help make sure no water gets in.

I plan on putting paper over the flashing, adding some more step flashing, and then the shingles. I'll get some pics in a few minutes to show you what I mean. Is there anything else I should be doing to keep the water out of the house?







My main concern is the water that can get under the over hangs and into that flashing that butts up against the house. All of this will have vinyl siding install over it, so what's to keep the water from reaching the flashing, and then stay behind the vinyl siding where it could reach the sheathing? The only thing I plan to put over the sheathing is some house wrap...so I'm not sure if that will do the job?

Thanks again for any advice
 

Last edited by jdlev; 10-09-14 at 05:01 AM.
  #2  
Old 10-09-14, 05:58 AM
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The way the dormer gutter is cut (with the angle of the roof) is typical. The "hole" they cut in the bottom "could" have a small 6" section of downspout that directs some of the water straight down into the other gutter. Hopefully they used downspouts on the other sections of gutter.

Looking at the shingles in the valley, it's my opinion that "weaving" the valley shingles and using 3 tabs is almost always a bad idea.

In picture 2, many local codes typically require 2 layers of ice and water shield at the eves of a roof, and ice and water shield in the valleys. Course, maybe that's not required in NC... And that ice and water shield would go under your flashing to protect the roof when it leaks.

Also in pic 2, metal step flashing (where each shingle is individually flashed as they are laid) is superior to continuous wall flashing. The wall that the corner post is on should have WRB behind it. The fascia cover should have a step flashing behind it as well so that all water is sure to shed on top of the WRB. Kind of like the ice and water shield on the roof, you should have applied the WRB first.

In pic 2, there will be a lot of water coming off the wall at the end of your wall flashing. That area of wall should have metal flashing or maybe even ice and water shield so that water coming off the roof doesn't overpower the WRB. Since I'm recommending you use step flashing, your first step flashing there should be a kickout flashing. Google image it if you don't know what that is. It will be the only thing that will prevent runoff from going behind your vinyl siding at that location.

In pic 3, I'm not fond of the style of drip edge (I prefer to use gutter apron) but some of that is to local taste. Gutter apron has a longer leg to direct water into the gutter, and it's not bent at a 90 like that stuff is... its bent at roughly 120 so the gutter not only slips behind it easier, but there is better coverage of the back side of the gutter. The right side of that flashing should be clipped to match the angle of the roof that it butts up against. Several layers of shingles will need to slip through there.

Pic 4, another location where WRB should have been on the wall 1st... then corner flashing where the wood fascia and drip edge meet the wall... then the fascia cladding would cover that corner flashing. The wall flashing where the roof and wall meet isn't as critical since its going to be behind the fascia and its so short... a one piece wall flashing would be fine. Some guys just let the ice and water shield roll up the wall. When the fascia is installed, it should be kept at least 1" above the shingles. Shingles will go under this space... but once the "exposure" of the shingles reaches the heel cut of the fascia, you should flash the fascia with step shingles. Then the fascia cover goes over the top of the flashing.

You're right that vinyl siding doesn't keep any water out. That's why the WRB and flashing is so important.
 
  #3  
Old 10-09-14, 06:48 AM
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Thanks again for the advice sleepy.

Few things. I think the best idea is definitely the kickout flashing. I have to make some progress on the paper today, so I don't think I have time to go back and rip out the regular sheathing and go with pressure treated plywood. I have a few things at my disposal to improve the water shedding ability though. I have primer I can put on the board, and may have some sort of waterproofing wood sealant (though I'm not entirely sure I have that). I know for a fact I have stain primer I could use. I have that flex seal rubber stuff I could coat it with. I could double up the house wrap.

Neither eave is as big as they look in the picture. They may overhang 8"-12". Keep in mind that they both have fascias that have yet to be installed, so one the side in pictures 3 & 4 shouldn't be exposed at all, and the other will have maybe 3 sq ft of shingles exposed at most. I think that's the reason the water damage was kept to a minimum, mainly because it was probably wind driven rain that had to have gotten under the eaves.

I have a bunch of 8"x 8" step flashing I plan on installing when the shingles go up to go over the L continuous flashing. I am also planning on running the felt paper up the side walls over the house wrap under the overhangs (not the entire length of the wall). Although, maybe it would be a great idea to just put some 15# paper over the house wrap on the sheathing, and run it all the way down the wall...I'm sure I should have some extra paper?

I'm not sure any ice or water shield is required here in NC. I was going to put 30# felt over the tops of the drip edge, but we get maybe 1-3 snows a year, and anything usually melts within a day or two.


So...any suggestions since I don't have time to rip out the standard sheathing to go with a pressure treated plywood?
 
  #4  
Old 10-09-14, 07:10 AM
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IMO that primer is a big waste of time. If water gets to the sheathing, you're in trouble, period. But if that's what they do there who am I to argue? lol

I am also planning on running the felt paper up the side walls over the house wrap
Try not to lap anything backwards. Think of it like this. Before you even put the siding on, ask yourself, can I spray a hose on the house and the sheathing won't get wet? If you run a few inches of felt paper "on top" of the housewrap, any water that's running down the housewrap would get behind the tar paper. So there's no point in that. Also running the felt up the wall doesn't lend itself to creating a nice sharp inside corner for your step flashing... the step flashing is all you need. Glad you've got some.

My recommendation would be to use ice and water shield, at least on the first course above the eves. It's not just called ICE shield, you know.
 
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Old 10-09-14, 08:01 AM
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I assume I want the one with the adhesive backside so it sticks to the eaves?

I could go with something like this...but I've read that Grace is the brand to go with?
Shop Owens Corning 3-ft x 66.7-ft Roof Underlayment at Lowes.com

An alternative that I could do is I have the 6" rubber roof sealant tape. I could put that along the eave and drip edge, and then lay the 30# over that? If something like that would work...it'd save me $150 on the ice & water shield...

Another question I had is do I need to seal the corners of the valley felt paper? If so, what should I seal them with...tar? rubber tape? maybe house wrap tape? I plan on weaving the paper across it, and then weaving the shingles over that, so I'm not really sure if it needs anything. I did 2 layers of 30# felt in the valleys. I tacked the first layer down with staples, and then used the plastic cap nails after putting the second layer down.
 
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Old 10-09-14, 08:23 AM
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If you aren't concerned about ice, the 6" tape would be better than nothing. My concern would be protecting the edges of the sheathing- to keep them from ever getting wet... and yes, something that actually sticks to the sheathing will be better than felt paper which just lays there. But IMO you should definitely be using the ice and water shield (the OC product would be fine) in your valleys, to meet valley lining requirements in IRC R905.2.8.2.

The paper that overlays the valley does not need any special tape, sealant or any other scheme to seal it. Once the membrane is laid in the valley (see IRC link) all that matters is that the felt paper be applied shingle style with the upper course lapping over the lower. If you like to weave it, that's fine. If you want to cut it to within 6" of the valley center, that's fine too. but you don't usually want to put any nails anywhere near the center of the valley... and that goes for felt tabs and shingle nails.

If you don't feel like replacing the 2 layers of felt that you have in the valley, I guess that's your business. But one misplaced foot can pretty easily rip that felt paper, then you've got a hole in your valley. So if you don't replace it just be very careful as you work around it.
 
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Old 10-09-14, 08:26 AM
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10-4 Thanks again for all your help sleepy. I appreciate it
 
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Old 10-09-14, 08:36 AM
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No problem. Glad you're doing it and not me. I just got paid so I'm taking a personal day today.
 
 

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