LESLIE: Phil in New York, welcome to The Money Pit. What can we do for you today?
PHIL: Yeah, hi. I had a question about installing a roof.
TOM: OK.
LESLIE: OK.
PHIL: And I guess – what happened was I got ripped off the first time and had to have the roof redone a second time. And they were talking about putting on, I guess, ice and water shield. And the question was to what extent do you need ice and water shield on the roof? Do you need to put it on the entire roof or – and also, do you need felt as well – in addition to the Ice and water shield.
TOM: Great question. Both products have a separate purpose. Now, Ice and water shield is designed to stop ice damming or water that backs up, say, from your gutters and getting into the roof surface. It’s typically only installed on the first …
LESLIE: At overhang areas?
TOM: Well, no. The first three feet. In the northern part of the country, it’s typically only installed at the roof edge. And the reason for that is because the overhang being out there in midair will freeze in the winter time and then water runs down the roof, it hits that overhang and it freezes because that’s going to be colder than directly over the heated space of your house.
LESLIE: Mm-hmm. It’s like the bridge may freeze before the road.
TOM: Exactly. And so, what happens is the water hits that ice dam and then backs up under the roof shingles and causes leaks. So, in our area of the country we typically only put this up to the first three feet.
Now, if you live down in Florida where hurricanes are an issue and shingles get ripped off of roofs and rain flies sideways on a regular basis, down there, typically they’ll put Ice and water shield sometimes across the entire roof.
Now, up here in New York I would put it on the first three feet and then in terms of the felt paper, that goes over that. But rather than put felt paper, there’s a high-tech synthetic material called Tri-Flex 30 that’s made by Grace. And it’s much more durable. It’s synthetic underlayment. Much more durable than tar paper. It can go on, it can be exposed to water, it’s not slippery and it’s going to be a better product to put under the roof.
Phil, good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.
Technically, for the Ice and water shield to be effective, it must be installed so that if comes 24” past your exterior wall. 3 feet, in most instances, doesn’t cut it. Say you have a 12” over hang (soffit), typically an 8” thick exterior wall, and now the pitch of your roof. A minimum of 6’ is required on most homes to meet code or even for the product to properly perform. On steeper than average roofs you may even need 9’ or 3 passes.
Thanks!
From a Midwest roofer trying to improve the industry and educate homeowners