question regarding ice and water layer on roof

[Gadgetman]

So my 15 year old house is going to be getting its 3rd roof shortly due to another hail storm. My question is how many layers of ice and water can one roof hold? Should the old layers be pealed off or do you just keep putting new layers over the old layers?. I am wondering if it isnt going to show a noticeable hump where the end of the I and W ends. Anybody have the answer?

[Farmboy1]

You can only install one layer of shingles over the top of another layer of shingles. A complete tear off should be in your future if I understand your question correctly.

Otherwise, Ice and water shield is normally applied to the bottom edge of roof, depending on how much overhang your house has. I believe it has to be 3' in from the edge of the house (where heat loss occurs), but don't quote me on that. One of the roofers on the site can give the actual number.

As far as taking off the Ice and Water shield, it should be removed down to the sheeting, and reinstalled. There will be no "hump" since there will be more layers over the top of it, think overlapping shingles, and will not be visible.

[walleyeseeker]

There was a change in the code last year that said you can no longer shingle over any previous roofing. Our building official now makes us remove the weather guard down to the sheeting. If you can not remove it, he makes us replace the plywood. Hope this helps.

[Roofer]

Only one layer of shingles can be on a roof now. No over-lays.

I&W cannot be removed and replaced. The sheathing can be replaced, but that is not the common practice. Another layer is put over the previous layer of I&W or you can possibly get by with just adding a layer of tar paper over it (best bet and I'll tell you why). The shingles will adhere to the I&W, making it almost impossible to remove the shingles. This stuff has made more work for roofers than any other product ever made.

Code is 2 ft. past interior wall line. This may be changed soon to one foot inside warm wall line, but for now it is 2 feet. Now, this depends on pitch......blah blah blah (if you need the info, I will give it out)

To answer the question, I would ask the building official what they want done. IMO, another layer is not needed, but if the insurance pays for it, you better be putting it on. If they pay to take up the sheathing, then you better be doing that. If the building official says to pull up the sheathing and replace, I would get the adjuster involved in paying for it ($95 per sheet).

[Surface Tension]

Its a pain staking job to pull off I&W shield off OSB and you'll end up taking chunks of wood along with it so your better off leaving it on. Two layers you won't notice, three layers you might. However its a lot easier to pull a second layer of I&W shield off the first. You'll either have a mineral or plastic film on top. You could always feather that transition out with a row of singles before you lay down the felt.

Code is 2' up the roof past the wall. Heres the concern, its thought that the I&W membrane can trap moisture coming from the interior thus the though of changing that to 1'. That concern would be on older homes with no vapor barriers, poor attic ventilation, and little insulation. Of coarse the above is prime for Ice Dams and IMO needs the 2' coverage above the wall.

[rtwills]

Only one layer of shingles can be on a roof now. No over-lays.

Are you sure about that?

If i am not mistaken you can go 2 layers of asphalt shingles unless you are in the hail damage zone.Although I do not do layovers I am pretty cretain you can do it in certain areas.

[Roofer]

You are right [YouNeedAuthorization]. The hail zone covers much of the state and that was the code last year. Not sure if they updated the map or codes on that or not. I would be willing to bet that if you get a permit, the building inspector will require a tear off. If it is an insurance claim, a tear off would be mandatory. The mortgage company and insurance company will be sure that it is torn off and reshingled before the final (depreciation) check is sent out.

[Gadgetman]

Thanks for the help guys. I am not going to shingle over the existing shingles, never liked that idea. I am just concerned about the ice and water layer at the bottom of the roof. It occurred to me that taking it off will probably wreck the sheeting below it, and taking the sheets off has to be a royal pain. Roofer, you never finished your reason for putting down a layer of tar paper over the existing ice and water. Insurance is paying for it so i am not interested in cutting any corners.

[Roofer]

You'll find out when you tear off the shingles. I don't want to give away any trade secrets.

[Gadgetman]

Thanks roofer....I think ?

[rtwills]

LOL Roofer ......surprise surprise..