Roofing Question - Ice and Water

[diiulio]

The intersection between the roof and a dormer, should the ice and water be rolled up the wall 5-6"? My roofer said the ice and water (he is using GAF Stormguard 2.0) says it doesn't roll in a corner and will not let the step flashing sit right. He said he would put ice and water over the stop flashing if I wanted along the wall.

The GAF install says to roll it up the roof 5", but I am not sure if it is a concern or not. My roofer isn't trying to skimp on materials because he is offering to put extra on.

Basically the ice and water butts up to the wall right now.

 

[Evilunclegrimace]

I have to call BS on your roofers comments. Ice and water will most definitely go up the wall with no issue. The stuff is not a 1/4" thick FFS. The step flashing goes over top of the Ice and water. And while 5"s is nice 2 -3 "s is plenty.

 

[readhead]

I would go with your roofer. I had a similar problem once and it telegraphed into more problems later. Also think about the path of water. If it gets behind the siding it will travel under the step shingles where it doesn't belong.

 

[matt_i]

I put the i+w up the sidewall and put the step flashing over it. No better way to do it imo.

The i+w doesn't bend perfectly cleanly but imo its good enough.

People seem to get weird over step flashings when it's going to require taking off siding to do it right...

 

[yeldogt]

Ice and water is to eliminate ice dam back up at the gutter line -- something the roof itself can not. Traditional roofs had steep slope or when metal became available a band of metal to eliminate water from ice dams.

Proper flashing at a dormer is all you need to prevent leaks -- I would cut the water shield tight to the dormer -- have the proper flashing do it's job.

 

[73fxe]

If it is over 75 degrees and sunny the I&W will bend tight. If it's cold You wont get a tight corner.

 

[Scott H in Wheaton]

GAF also calls it Leak Barrier, and basically you should use it wherever the shingles get interrupted, like a sidewall, a chimney, a stove pipe, a skylight, a plumbing vent jacket/boot, etc.
In this region we run two 3' courses from the gutters up the roof deck as well.

 

[Lelandwelds]

If it is over 75 degrees and sunny the I&W will bend tight. If it's cold You wont get a tight corner.

GAF also calls it Leak Barrier, and basically you should use it wherever the shingles get interrupted, like a sidewall, a chimney, a stove pipe, a skylight, a plumbing vent jacket/boot, etc.
In this region we run two 3' courses from the gutters up the roof deck as well.

The commercial guys have a mastic alternative. That and I & w are the big guns for water control. They both hate UV long term. There is a paint roller water proofing the commercial guys use over entire OSB walls and roofs everywhere.

Quit using crappy asphalt shingles.

 

[n20junkie]

The ice and water will bend tight if you do it right. A narrow hand roller goes a long way to getting it tucked into the corner properly.

Dormers love to leak, and ice guard is also a good protection from wind driven rain and snow buildups that melt weird and cause all sorts of troubles.

Step flashing works well, but it is rarely installed properly, and even then, it can fail in a high wind or irregular snow situation.

 

[larry4406]

I think I would get a different roofer.

In the production homes my company builds, we cover the entire dormer 100% with ice water shield first ensuring that the roof to dormer transition is centered on the roll. All cornice is later applied over the ice guard.

Our warranty issues with dormer leaks has gone to zero.

Grace ice guard has a zip string on it specifically for use at this application.

 

[yeldogt]

Ice and water has become another in a long line of products that people think will solve all problems .. well, if it works for this .. why not that.

Sure -- cover everything with it. That way any mistake on the actual roof will not matter until the ice and water fails and then you can't figure out where the roof is leaking ... or the roof is leaking on top of the ice and water and it's always wet under the shingles. Just look around --- see the number of roofs with mold staining ... and they get enough sun.

I'm not knocking the product -- it's great for the intended purpose. Remember it's a vapor barrier -- and covering a whole roof or dormer w/ conventional insulation in the bay under it will stop the roof sheathing from drying to the outside.

They have already stopped using it around windows and doors around my beach house -- have returned to old school methods of pans. It eventually fails ...the predictable leaks and rot starts.

I'm wondering how the zip walls are going to be in 20 years -- will the tape hold? My guess is no.

 

[readhead]

Yeldogt, that was my original point, though not well stated. Water tight buildings have been built for a few hundred years before all this sticky stuff came along. Please don't misunderstand me, there are some great products with good results. However the basics and best practices are still the most important steps. Proper flashing is probably the biggest source of building failures in construction. Unfortunately as time goes on new waves of installers, not craftsmen, are not being taught tried and true methods. Someone who doesn't know better is now teaching the next guy and so on.

To the OP, discuss with the roofer what his flashing plan is and do some homework to see if it makes sense. Will there be a kick out flashing at the eave? Will there be counter flashing over the step flashing so the roof can be replaced down the road without removing siding? Lots of things to look at. Best of luck.

 

[yeldogt]

Yeldogt, that was my original point, though not well stated. Water tight buildings have been built for a few hundred years before all this sticky stuff came along. Please don't misunderstand me, there are some great products with good results. However the basics and best practices are still the most important steps. Proper flashing is probably the biggest source of building failures in construction. Unfortunately as time goes on new waves of installers, not craftsmen, are not being taught tried and true methods. Someone who doesn't know better is now teaching the next guy and so on.

To the OP, discuss with the roofer what his flashing plan is and do some homework to see if it makes sense. Will there be a kick out flashing at the eave? Will there be counter flashing over the step flashing so the roof can be replaced down the road without removing siding? Lots of things to look at. Best of luck.

Agree.

I'm an old building nerd. While I have built two modern homes -- redoing historic stone is my favorite. You can learn a lot looking at slate and wood roofs from 100 years ago (yes some wood roofs can last that long).

Most of what was learned over centuries has been lost -- every time you get a tube of caulk out you should ask yourself .. what's going to happen when this fails and what did they do before caulk ?

I hired a building envelope architect for my most recent slate project because it was too complex to take any chances.

 

[The Tool Tyrant]

Will there be counter flashing over the step flashing so the roof can be replaced down the road without removing siding?

Huh...where have I heard this before? Makes a GREAT deal of sense to me!

 

[diiulio]

I have talked to the manufacturer and they said to roll it up 5".

I talked to the roofer and will do it, but is not comfortable with it.

I have not decided what to do. He is not here today because of another job, which I am ok with so it gives me some time to digest it. He has been roofing since he was young, he has been doing roofing 35+ years. He came recommended by a couple of people here in town. I was told I was all set when I told a local framer I had the roofer I did.

I think I may just go up on the roof with him and have him show me why it can't work and then make the decision up there.

Here are horrible pictures because it gets dark so early here, but this is what I have from last night when I got home.

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[yeldogt]

I think with it all new, flat and square -- it's not going to matter. Especially, if you are using vinyl siding. It's just creates another thickness at that point.

The leak point is down at the corner any way. What's the front flashing ?

 

[readhead]

I would run a 1x4 down the rake at the side walls and across the front to put the step flashing against and the flashing at the front of the dormer then a counter flashing over that and then you will have a nice place to land the siding. If you need to reroof in the future You will not have to remove any siding.

 

[The Tool Tyrant]

The front window wall isn't where the BIG issue is as the I&W only need to bend to 45° at that point. Going up the rake it will need to bend to 90°.

You already know that I'm in total agreement with 'readhead' and recommend using Z-Bar flashing. Having to rip off siding to re-roof is asinine.

 

[6768rogues]

In a perfect world, I would run the ice and water shield up the dormer wall. Then install the roofing and step flashing. Then put house wrap on the dormer overlapping the step flashing and ice and water shield, taping the bottom with tape made for the purpose.. Then siding on the dormer.

 

[77Birdman]

He is probably old school, hence his hesitation. When we roof and have that situation we always run the ice shield up the wall. There is no problem with it bending an inside corner. There are many good uses for it. Properly flashed it really isn't necessary, but in this day and age there is no sense in not putting it on.

 

[850xpeps]

I put the i+w up the sidewall and put the step flashing over it. No better way to do it imo.

The i+w doesn't bend perfectly cleanly but imo its good enough.

People seem to get weird over step flashings when it's going to require taking off siding to do it right...

Wrong way to roof. If systems fail you don’t have your proper lap. Ice and water on roof flashing on top ice and water over that. I would prob just leave the ice and water off the doomer as it’s vertical and shouldn’t have more than 5 “ of snow built up there anyway. If you do then clean it off. I would spend more money on ice and water the entire roof parts and valleys properly.

 

[alwaysFlOoReD]

I would run a 1x4 down the rake at the side walls and across the front to put the step flashing against and the flashing at the front of the dormer then a counter flashing over that and then you will have a nice place to land the siding. If you need to reroof in the future You will not have to remove any siding.

This is the correct way to do it. I haven't seen any new construction company up here do it. It's an extra cost that the company doesn't want.
PS: I do new construction and renovation sidings and have done a fair amount of re-roofs over the course of 35 years.

 

[diiulio]

Thank you for all of the feedback. I appreciate your time in responding. I will let you know how it turns out.