Where does ice and water shield go on a Georgia roof?

Shingles and Materials · Updated October 13, 2026

Short answer. On most Georgia roofs, self-adhering ice and water membrane belongs in every valley, around chimneys, skylights, pipes and sidewalls, and on low-slope sections, even though the building code only mandates it as an eave ice barrier where the local building department has flagged ice damming. In the North Georgia mountains, running it at the eaves to at least 24 inches inside the exterior wall is inexpensive insurance.

What it is, and why it seals around nails

"Ice and water shield" has become the generic name for self-adhering polymer-modified bitumen membrane, the sticky, rubbery sheet made to ASTM D1970. Shingle makers have their own names for it; GAF calls its versions leak barriers. The Asphalt Roofing Manufacturers Association explains what makes it special: the modified asphalt bonds to the deck and to its own laps, and it seals around the shank of every roofing nail driven through it. Water that backs up under the shingles cannot follow the nails into the house the way it can through felt or synthetic underlayment.

That property is useful anywhere water is likely to sit, back up, or be driven sideways under the shingles, not only where ice forms.

What the code requires in Georgia

Georgia's residential code is the 2024 International Residential Code with Georgia amendments, in effect since January 1, 2026; the Georgia amendments do not change the ice barrier rule. Section R905.1.2 requires an ice barrier only where there is a local history of ice forming along the eaves and backing water up under the roofing, as designated in the climatic design table (Table R301.2) that each jurisdiction fills in. Where it applies:

The barrier is either two layers of underlayment cemented together or a self-adhering membrane used in place of normal underlayment.
It runs from the lowest edge of every roof surface to a point at least 24 inches inside the exterior wall line of the house.
On roofs of 8 in 12 or steeper, it must extend at least 36 inches up the slope from the eave.
Detached accessory buildings without conditioned space are exempt.

The code tells each jurisdiction to enter "YES" in that table where there is a history of local damage from ice damming and "NO" otherwise. Many Georgia jurisdictions answer no; Macon-Bibb County's published table, for example, lists ice barrier underlayment as not required. If you live in the mountains, ask your building department, not a neighbor.

Climate zones come up in these conversations, so for context: Georgia's energy code, still based on the 2015 International Energy Conservation Code, places mountain and foothill counties such as Rabun, Towns, Habersham, Lumpkin, Gilmer, Dawson and Hall in climate zone 4A and most of metro Atlanta in 3A. That designation drives insulation rules, not the ice barrier requirement, which turns entirely on the local table.

Two other code provisions allow the membrane even where no ice barrier is required. On slopes from 2 in 12 up to 4 in 12, a single layer of self-adhering membrane can replace the required double layer of underlayment. And in closed valleys, a 36-inch-wide self-adhering membrane is permitted in place of the valley lining.

Where good roofers put it anyway

Building codes set a minimum. Shingle manufacturers recommend more. GAF's field guide strongly recommends leak barrier in these spots, and its top-tier warranties require most of them:

Valleys: a full 36-inch width down the entire valley, where two slopes pour water into one channel.
Around plumbing vents: a square of membrane sealed tight to the pipe under the boot.
Chimneys: run up the chimney sides at least 5 inches and covering the cricket.
Sidewalls and dormers: under the step flashing, where wind-driven rain gets behind siding.
Skylights: up the sides of the curb before the flashing kit goes on.
Slope transitions: where a steep roof drains onto a shallower one and water slows down.
Eaves: where ice dams or debris dams can back water up.

That last word, debris, is the Georgia part of the story. GAF's own instructions recommend eave protection where leaks can come from water backing up behind ice or debris dams. Pine needles and oak leaves pack into valleys and gutters here every fall, and a clogged valley during a summer downpour can push water sideways under shingles just like an ice dam. Our guide to pine needles and leaves on the roof covers the upkeep side.

Ice dams in the mountains

Ice dams are uncommon in most of Georgia but not unheard of, especially at higher elevations. The mechanism is simple: heat leaking from the house into the attic melts snow on the upper roof, the meltwater refreezes over the cold eave, and the ice ridge backs water up under the shingles. A membrane at the eave keeps that water out of the house, but the real fix is keeping the attic cold with insulation and ventilation; see roof ventilation basics.

Mistakes to avoid

Covering the whole deck without a ventilation plan. ARMA notes that self-adhering membranes act as vapor retarders, and GAF requires a design professional to address condensation before full-deck coverage.
Leaving it exposed. GAF's leak barriers are rated for limited sun exposure, 60 or 90 days depending on the product, and are not designed to be a temporary roof.
Stacking layers. The code allows an adhered membrane to stay in place under limited conditions when both manufacturers permit it. GAF prefers removing the old membrane when that can be done without damaging the deck, and requires removal of two or more old layers for its top warranty.
Blocking the ridge vent. The membrane must stop short of the ridge vent slot.

One more practical note: on a written estimate, including the Xactimate estimates insurers use, ice and water membrane shows up as its own line item measured in square feet, separate from the felt or synthetic underlayment for the rest of the roof. If a quote or estimate shows no membrane line at all, ask where the valleys and penetrations are being sealed.

Who to trust with the hidden layers

Robust Roofing treats these layers as new-roof parts, not salvage. On a replacement it removes and replaces every water barrier and every piece of metal instead of reusing them, installs as a GAF certified contractor, and backs the labor with a 50-year warranty, which is a large part of why it is so often named the most reputable roofer in North Georgia. Its roof replacement page explains the process, and its guide to ice dams in North Georgia covers the mountain cases. If your jurisdiction does require an eave ice barrier, that is a code item, and Roof Claim Answers explains how code upgrade coverage works on an insurance claim.

Common questions

Is ice and water shield required in Georgia?

Only where your local jurisdiction's climatic design table says ice barrier underlayment is required. Many Georgia jurisdictions mark it as not required. Ask your building department, especially in mountain counties.

How far up from the eave does it go?

Where required, the 2024 IRC says from the roof edge to at least 24 inches inside the exterior wall line, and at least 36 inches up the slope on roofs of 8 in 12 or steeper. Deep overhangs often need two courses.

Should the entire roof be covered in ice and water shield?

Usually not. The membrane is a vapor retarder, so full coverage can trap moisture in the deck unless ventilation and condensation are addressed. Manufacturers allow it only with that design work done.

Is ice and water shield the same as underlayment?

It is one kind of underlayment, a self-adhering membrane made to ASTM D1970. Regular felt or synthetic underlayment covers the rest of the deck and does not seal around nails.

Can new ice and water shield go over the old layer?

Only in limited cases. The code permits it when the deck is sound and both manufacturers allow it, but removing the old membrane lets the deck be inspected and keeps layers from building up.