Ice and Water Shield
Also called: ice and water barrier, self-adhering membrane, peel and stick
Ice and Water Shield is a self-adhering waterproof membrane applied at the roof's most vulnerable points, typically eaves, valleys, and around penetrations. It seals around fasteners, and where local code requires it, replacing a roof usually means installing it whether or not the old roof had any.
What it means
Ice and water shield is a self-adhering waterproof membrane, supplied in rolls with a peel-off backing, applied directly to the decking at the roof’s most vulnerable points before the underlayment and covering go on.
The characteristic that matters is the adhesive. Where an ordinary underlayment is nailed down and therefore perforated by its own fasteners, this membrane seals around anything driven through it. A nail penetrating it is gripped tightly enough that water cannot follow the shank down into the deck.
Where it goes and why
At the places where water does not behave the way a roof assumes it will.
Eaves are the classic location. In cold climates, snow melts higher up a warm roof, runs down, and refreezes at the cold overhang, building a dam of ice. Water then pools behind the dam and works upward under the shingles, which are designed to shed water running downhill and not to resist standing water pushing uphill. A membrane at the eaves is what stops that reaching the deck.
Valleys are the second location, because they concentrate the flow from two slopes into one channel and carry far more water than any other part of the roof.
Penetrations, sidewalls, and low-slope sections make up the rest: anywhere the geometry interrupts clean drainage.
Why it shows up as a claim dispute
Because it is frequently required now and frequently absent from the roof being replaced.
Codes have progressively required self-adhering membrane in these locations, and the requirements vary by jurisdiction and by climate. A roof installed decades ago may have none at all. When that roof is replaced, the new one generally has to comply with what the local authority requires today.
That creates a gap between restoring what was there and building what is now required. The contractor cannot lawfully build the old assembly. The carrier may take the position that its obligation is to restore the pre-loss condition rather than to fund an upgrade.
Whether the difference is covered depends on ordinance or law coverage in the policy. Where it exists, code-triggered upgrades are typically payable within its limits. Where it does not, the homeowner may fund the difference.
None of that is the contractor’s determination to make, and specific code requirements are a question for the local building authority rather than something to assert from memory.
Common mistakes
Presenting it as an optional upgrade is the first. Where code requires it, it is not optional.
The second is failing to raise the ordinance or law question early, which leaves the homeowner discovering a funding gap late.
The third is installing it only at the eaves when the roof’s geometry calls for it elsewhere.
On the call
This line item is a frequent source of confusion because homeowners see a product they never had before appearing on an estimate. It is normally a code-driven requirement rather than an upsell, and whether the carrier pays for it can turn on ordinance or law coverage.
This is how our agents handle it on storm appointment calls and day-to-day roofing answering service intake.
Questions people ask about ice and water shield
- Why is it on the estimate when the old roof did not have it?
- Because requirements have changed. Building codes have progressively required self-adhering membrane at vulnerable areas, and a roof replaced today generally has to meet the current requirement rather than reproduce what was there before.
- What makes it different from ordinary underlayment?
- It is self-adhering and it seals around fasteners. A nail driven through it is gripped by the adhesive, so water cannot track down the shank. Standard underlayment is mechanically fastened and does not seal around penetrations in the same way.
- Will insurance pay for it if the old roof did not have it?
- That is an ordinance or law question. Where the policy carries such coverage, code-required upgrades triggered by the repair may be payable. Without it, the carrier may decline to pay for work that exceeds restoring what was there, and the homeowner covers the difference.
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