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Ice shield and roof membrane install

Mick182's picture

Due to a litttle less money in the budget, looks like I will be doing the roofing i had planned to pay out. Not a problem, done a few roofs over the years, but not in quite some time.

I really like the ice shield and membranes on the market these days for roofs etc...I'm excited about using the Grace product.

I have a few questions I would like to be familiarized with for a proper use of these products.

1) areas to be ice shielded: does the ice shields run along the eaves and up the rakes? or just along the eaves? Is 3' wide the proper size shield?

2) does the ridge get the ice shield over it also? 3' wide?

3) Do the valleys also recieve the membrane? If so, how do i apply this, as the framer framed over the (1) layer of existing shingles to tie into the roof for the "reverse gable" (I think that is the right term). So the new framing is sheathing' and then I have the existing shingles that i have to tie into (valley). So as far as the valley's  I'm unsure if or how a membrane is installed. I would imagine this would be a smaller width membrane if used, correct?

4) Also, just a couple more questions on drip edge. Is the drip edge that is used for the eaves( the kind that protrudes out to extend a bit over the gutter to help with water runoff) also used up the rakes? or is the type that looks more like an "end cap" used up the rake?

Lot of questions but would appreciate anyone chiming in on any of the four, or all four if you have the answers. thanks so much. Need to get on this soon, while weather is still good. But don't want to move ahead until I understand correctly.

More questions: 1) Where do (post #195141, reply #1 of 11)

More questions:

1) Where do you live?

2) What's the eave overhang?

3) What's the slope of the roof?

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

1) Ice shield is often used (post #195141, reply #2 of 11)

1) Ice shield is often used at the eaves. Whether you need it or not depoends on the climate you're in. (And your local codes)  You might need more than 3' if you have wide overhangs, a low pitch, or poor attic insulation.

2) There's no reason to use it at the ridge.

3) Definitely use it in the valleys. Before I put it down I like to lay in aluminum flashing to support it and keep it from getting a crease in it.

4) Drip edge is used on all edges of the roof.

It was getting "past my (post #195141, reply #5 of 11)

It was getting "past my bedtime" when i made original post  :)

I should have given a bit more detail. Job location is in Garden City, NY. The pitch of the roof is @ 5/12.

I planned on installing 3' ice shield on eaves and valleys, no question.. I also figured i would run it up the rakes as I have enough material, even if it weren't necessary.

When you look product website( i.e. Grace) they show ice shield everywhere.....eaves,rake, ridge, valley etc....

Figured they want to sell the product so make it appear that it is necessary everywhere. :)

Drip edge.........same style drip edge for rakes and eaves or are sperate ones use?. I'm familiar with the drip edge that skirts the water out to the gutter on the eaves. What type is best for rakes where no gutters will be?

As far as what you mentioned regarding aluminum flashing underneath valley membrane what is the technique? Just a roll type flashing rolled out from top to bottom? Do you pre bend it to form the valley angle?




Re your valleys, you're going (post #195141, reply #3 of 11)

Re your valleys, you're going to have to take up the shingles along the valley, put down the rubber, then relay the shingles, using whatever weaving technique you've got planned.  Would be good to have a shingle thief.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Some Answers from a roofer (post #195141, reply #4 of 11)

Ice and water shield has become a standard, but it is not always needed. Still, it is a good insurance policy. Just don't count on it to cover the sin of poor workmanship like so many do. Typical requirement is to run it three feet higher up the roof than the exterior wall at eaves - none needed at rake. So if you have no overhang( Eeghads!!!), then one course of I&W would suffice, but with a 2' roof overhang, you'd need two courses. The reason for the IW is to prevent ice damns from causing leaks. IMO, it is far better to design and build in such a way as to prevent the ice damn in the first place with good insulation and ventilation to assure a old roof surface. Ice damns are caused when the roof surface above the living space is warmed by escaping BTUs which melt the snow there. That water then runs down onto the overhang area where it is colder and re-freezes day after day, until the ice damn is thick enough to prevent water from running off the roof. Instead, it pools and backs up under the shingles, causing leaks that damage the home. How wide the overhang, and how steep the roof, and how well vented the attic space are all factors here. I would definitely line the valleys with IW. Whether 3' or 6' depends on the pitch of the roof and the style of valley used. As already mentioned, you need to remove the shingles run into the framing. That was probably a poor method for this extension, but there may have been reasons for doing it that way. Do you plan to shingle over the old or tear off the entire to re-roof?



Oh Well,

We did the best we could...

Good info Piffin, (post #195141, reply #6 of 11)

Good info Piffin, thanks.

There are no overhangs (reason being to match identical existing gable extension as mentioned in post pitch is aroung 5/12

. Gable roof which will be a cathedral ceiling interior, so no gable vents.

Valleys and eaves a definite on 3' ice shield.


I was in roof supply house today and talking with the two guys at the desk, and there happened to be two foofers there also (one who is the main installer that the supply house refers out). Really nice guys, who seemed to really take pride in their trade and appeared happy to share what they said has worked for them for many years. One even had a portfolio of his work with him.

"All" of them said that not a one of them uses any type of metal flashing in their valleys ever (unless an open valley), just a membrane and shingles laid correctly, 

Also said,  no Ice shield on rakes, none on ridge, no drip edges on rakes...eaves only. Of course if roof pitch is on the flatter side more ice shield would be necessary accordingly in areas.

So for the most part they were saying ice shield the valleys and eaves, drip edge the eaves and shingle properly and you'll be just fine when the water comes. Not to say that it's wrong to include ice shield "all over the place".....just not necessary for a watertight job. But all were very adomant on "not" using metal in a valley.

So my take from that conversation was to 3' ice shield the valley and eaves, drip edge the eaves. I forgot to ask them how to handle laying the felt over the membrane at the valley????????

BTW, my mistake about the framer framing over the existing shingle. He cut out the area for the 'sleeper" to attach into the existing roof deck. And, no, the existing shingles are not coming off, just tieing in new to the old.

Drip edge is always used here (post #195141, reply #7 of 11)

Drip edge is always used here -- the type that projects about an inch out from the fascia.  It prevents the edge of the shingle from sagging where it overhangs the edge of the roof, protects the shingles if you ever put a ladder up, and simplifies life for the roofer since he can make his cut against the drip edge vs having to judge an inch out from the fascia.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

I&W whole roof? (post #195141, reply #8 of 11)

I am in Vancouver Canada and it’s pretty much a rainforest here for 6 months of the year. Anyone install Grace Ice and Water over the entire roof? The way it seals around nails I think this would pretty much guarantee it would never leak.


For an owner-builder it would also remove the "roofer risk" from the schedule as this could be installed fairly quickly by less skilled workers. Mr. Roofer can come anytime later....



Hi John hijacker ;)    (post #195141, reply #9 of 11)

Hi John hijacker

;)    LOL

I have done entire roof with I&W under slates or tiles before, where it is a lifetime roof, and takes time to install but interior dry is important Now.

But because it also seals against moisture rising from under, it is absolutely imperative that the space under it be vented well - no cathedral roofs etc


As a roofer, I would NOT want to roof something the HO or a less skilled crew had applied though. This membrane is a part of the roof and takes skill to apply correctly. I cannot count high enough to tell you all the messed up I&W  have seen. If I am the roofer, don't ask me to just do half the roof after you did the first half. I am going to get the credit or the blame no matter who messed it up.



Oh Well,

We did the best we could...

messed up how? (post #195141, reply #10 of 11)


Can you tell me or the original poster what kind of problems you have found?

As far as I can tell avoiding bubbles would seem to be the only issue.



Sure thing (post #195141, reply #11 of 11)

Edges that turn up walls and chimneys, etc, that are rolled up instead of folded neat crease and tucked. Laps that face uphill Wrinkles, wrinkles, and more wrinkles. Gobs of wads of extra thick mistakes or patches covering mistakes. Seams that do not lap even an inch. That is all that comes to mind right now, but I have a full belly slowing the blood to my brain tonight, being Turkey PM



Oh Well,

We did the best we could...