Every replacement quote you get in the Capital Region should tell you exactly where the ice-and-water shield is going and how far it extends. If a quote doesn’t mention it, ask. If the quote lists it but doesn’t specify coverage, ask. If two quotes are meaningfully different in price and the cheaper one is skimping on shield coverage, you now know why.
Ice-and-water shield is the single most important product improvement in residential roofing over the last thirty years. On roofs installed before about 1995, this membrane either didn’t exist yet or was used sparingly. On roofs installed today, if the job is done right, it’s the piece of the assembly that keeps water out of your house even when everything above it fails.
What it actually is
Ice-and-water shield is a self-adhering, rubberized asphalt membrane that gets installed directly onto your roof sheathing, underneath the underlayment and shingles. It’s a physical barrier that water cannot penetrate — not from wind-driven rain, not from ice dam backup, not from a torn shingle above it. The material is flexible, sticks to the deck without mechanical fasteners, and self-heals around nail penetrations from the shingles that get installed over it.
The color is usually black. The width is typically three feet per roll. The thickness matters more than most homeowners realize — cheaper products are thinner and don’t handle temperature swings as well.
Where it’s supposed to go
This is where quotes diverge, and where you should pay attention.
Along all eaves, six feet up from the drip edge. This is code in New York for our climate zone. Six feet of continuous ice-and-water shield along the entire lower edge of every roof plane. The purpose is to protect the eave from ice dam backup — when snow melts, refreezes at the cold eave, and forces water back up under the shingles. Six feet gets you past the interior wall line on most homes, so if ice damming happens, the water sits on the membrane instead of getting into your ceiling.
In every valley, top to bottom. Valleys are where two roof planes meet and water flow concentrates. A blocked valley or a torn valley shingle can dump a lot of water in a small area. Full ice-and-water shield in the valley, top to bottom, at least three feet wide, is the belt-and-suspenders detail.
Around every roof penetration. Chimney flashings, skylight flashings, plumbing vent stacks. Any place something pokes through the roof, ice-and-water shield gets folded around the base before the flashing goes on. Sometimes called a “chimney apron” in the field.
Along rakes and hips if the roof pitch is low. Low-pitch roofs have less water shedding capacity, so we extend shield coverage to protect the vulnerable edges.
What cheaper quotes skimp on
The quickest way to lower a replacement quote by a thousand dollars is to reduce ice-and-water shield to code minimum, use a thinner product, or skip the valley and penetration coverage. On a smaller Capital Region home this might save the roofer three or four rolls of material — call it $200 to $400 in wholesale cost — but it costs the homeowner years of confident coverage.
We spec full valleys and penetration wraps on every quote. It’s not the piece of the roof we cut on to compete on price. If a quote you’re comparing is significantly cheaper and the ice-and-water coverage is minimal, that’s usually where the difference is.
Why it matters more in the Capital Region than most places
Our climate is specifically brutal for eave protection. We get freeze-thaw cycles that push snow melt down warm-side slopes to cold-side eaves, then freeze it into dams that back water up under the shingles. We get windward-slope wind-driven rain that pushes water sideways under shingle tabs. We get late-season snowstorms in April that dump on tender spring roofs.
Ice-and-water shield is the layer that quietly keeps all of that out of your house. When it’s installed correctly, you never think about it again. When it isn’t, you find out during the third winter after the replacement, when a ceiling stain shows up over the master bedroom and the roofer who installed the roof isn’t returning your calls.
What to ask about it in a quote
“Six feet of ice-and-water shield along the eaves — confirmed?” Should be yes.
“Full ice-and-water shield in the valleys, top to bottom?” Should be yes.
“Around chimney and skylight bases?” Should be yes.
“What brand and thickness of shield?” Grace, CertainTeed Winterguard, Owens Corning WeatherLock, or GAF Weather Watch are all reputable. Thickness typically 40 or 60 mils. If they can’t answer the brand, they haven’t spec’d it — they’re just going to grab whatever’s cheapest at the supply house.
“Is the ice-and-water shield included in the warranty?” Yes on our jobs. Some cheaper jobs treat the membrane as consumable and exclude it. That’s not standard on any job we run.
Paul Sandul, Elite Contracting. Clifton Park.
The full walkthrough of what goes into a proper Capital Region replacement is in The 27-Year Roof pillar. Service page: Roof Replacement.