Ice and Water Shield: When You Need It + 2026 Cost Per Square

By The Roofing Brief Team | Last reviewed: October 2026

Ice and water shield cost in 2026 starts at about $40 to $112 per square (100 sq ft) of membrane for mainstream rolls at retail, before labor, and IRC R905.1.2 requires it at the eaves wherever your jurisdiction’s Table R301.2 records a history of ice forming along the eaves. Related: Ice dam protection membrane code requirements. The peel-and-stick rubberized asphalt membrane bonds to the deck and seals around shingle nails, so meltwater backed up behind an ice dam cannot run through the nail holes. Code-minimum coverage runs from the eave edge to a point at least 24 inches inside the exterior wall line; on eaves with a history of heavy ice dams many owners choose to extend it further up the slope.

Short answer: what ice and water shield costs and why it is required

Ice and water shield is a self-adhered, rubberized asphalt waterproofing membrane that goes between the roof deck and the primary underlayment at the most leak-prone areas of the roof. Material cost is set by the roll: a 225 sq ft roll of Grace Ice & Water Shield listed at $179.00 to $251.17 (about $80 to $112 per square), while a 200 sq ft roll of GAF WeatherWatch listed at $80.52 to $99.97 (about $40 to $50 per square), both in retail listings checked October 19, 2026. On a full reroof the same crew lays the membrane before the field underlayment, so ask the roofer to price it per square and to state how many courses the eave needs; the worked example below shows why that course count, not the roll price, moves the total most.

The reason for the IRC code requirement is ice damming. Snow melts over heated attic space, runs down to the colder eave, and refreezes into a ridge of ice that traps more meltwater behind it. That water backs up the slope under the shingle courses, where felt and synthetic underlayments are not designed to stop it. A self-adhering membrane meeting ASTM D1970 bonds to the deck and seals around nail shanks; Grace’s data sheet still warns that it “may not self-seal open fastener penetrations” left when nails are pulled, which is why removed fasteners must be patched.

IRC R905.1.2 code requirements explained

The International Residential Code, Section R905.1.2 (Ice Barriers), is a model code that most states adopt, often with amendments. The 2021 IRC Chapter 9 text reads:

“In areas where there has been a history of ice forming along the eaves causing a backup of water, an ice barrier shall be installed for asphalt shingles, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shingles and wood shakes. The ice barrier shall consist of not fewer than two layers of underlayment cemented together, or a self-adhering polymer modified bitumen sheet, shall be used in place of normal underlayment and extend from the lowest edges of all roof surfaces to a point not less than 24 inches inside the exterior wall line of the building.”

What this means in practice:

• “Areas where there has been a history of ice forming” is not a temperature test. Each jurisdiction answers yes or no in the ice barrier column of its adopted Table R301.2 (Table R301.2(1) in the 2018 IRC and earlier). A few states substitute their own trigger, such as New Jersey’s 25 degree January test. Some states answer yes statewide: Connecticut does, and it also amends the code to add a sealed deck seam requirement. Our Connecticut guide covers Connecticut’s sealed deck seam rule.
• The 24-inch point is measured inside the exterior wall line, not from the gutter or the fascia. For an 18-inch eave overhang, that puts the up-slope edge of the membrane 42 inches (measured horizontally) in from the drip edge.
• “Self-adhering polymer modified bitumen sheet” is the peel-and-stick membrane sold by every brand in the table below; each lists ASTM D1970 on its data sheet or ICC-ES report.
• The double-layer alternative (two plies of underlayment cemented together) is still legal, but it is built on site from felt and cement rather than bought as a tested D1970 sheet, so few residential roofers use it.

Note what the code does not do: it does not tie the ice barrier to an energy-code climate zone or a list of states. Whether it is required at your address depends only on your jurisdiction’s Table R301.2 entry, so ask your building department. Coverage beyond the eave minimum, such as wider eave runs, rakes or a full deck, is not a code requirement; it comes from the shingle manufacturer’s installation instructions or from your roofer’s judgment.

Where it must go: eaves (24 inches past the wall)

The eave is the critical zone. Code-minimum coverage runs from the lowest edge of the roof to a point at least 24 inches inside the exterior wall line (on slopes of 8:12 or steeper, at least 36 inches measured along the slope from the eave edge). With an 18-inch eave overhang, that equates to 42 inches of horizontal coverage. Measured along the slope the membrane must be longer: 42 in x 1.118 = 47 inches at 6:12, and 42 in x 1.414 = 59 inches at 12:12. Both are wider than one 36-inch roll, so that eave needs two courses.

If your roof pitch is	Slope factor	One 36 in course is enough when the overhang is	Example
4:12	1.054	10.2 in or less	12 in overhang: 2 courses
6:12	1.118	8.2 in or less	6 in overhang: 1 course
8:12	1.202	6.0 in or less (the 36 in along-slope minimum is met by one full course)	12 in overhang: 2 courses
12:12	1.414	1.5 in or less	Almost every 12:12 eave: 2 courses

The slope factor is the square root of 1 plus (rise/12) squared; the overhang limit is 36 in divided by the slope factor, minus the 24 in the code requires inside the wall line. Laps are ignored in this check, so treat a result within an inch of the limit as two courses.

Installation sequence at the eave:

1. Install drip edge on the eave first. Grace’s data sheet says to place metal drip edge or wood starter over the membrane, so follow your membrane maker’s sheet for which goes on top.
2. Lay the first course of ice and water shield, extending up the slope per code.
3. If the eave coverage needs a second course, lap it over the lower course: Grace specifies side laps of at least 3.5 in (marked by a dashed line on the film) and end laps of at least 6 in; CertainTeed WinterGuard Granular and HT call for 4 in side and 6 in end laps per ICC-ES ESR-1492 (reissued January 2026).
4. Run synthetic underlayment over the top edge of the ice and water shield so every lap sheds water.

Where it must go: valleys, penetrations, skylights

R905.1.2 covers eaves only and does not mention valleys. IRC R905.2.8.2 permits a self-adhering membrane complying with ASTM D1970 in place of the valley lining, and shingle manufacturers’ installation instructions, which the code makes enforceable, often call for membrane in valleys and around penetrations.

Valleys. A 36-inch wide strip of ice and water shield runs full-length down every valley, centered on the valley line; 36 inches is the closed-valley lining width in IRC R905.2.8.2. The Grace Ice & Water Shield data sheet (updated March 20, 2026) says to apply the membrane in valleys before the eaves, working from the center of the valley outward and from the low point up.

Penetrations. Plumbing vent stacks, B-vent flues, electrical masts, satellite mounts, and any other roof penetration get a membrane collar that goes down before the field underlayment, with the boot or flashing on top. Collar size is set by the shingle or flashing maker’s instructions, so ask the roofer which document they are following.

Skylights. Membrane wraps the skylight curb on all four sides before the maker’s flashing kit goes on. Skylight flashing kits come with their own instructions for the membrane collar, and that document governs the lap up the curb.

Sidewalls. Where a roof plane meets a vertical wall (a dormer side, a chimney side, a step-up roof), Grace’s data sheet says to extend the membrane “above the highest expected level of snow and ice on the wall sheathing”. The step flashing and counter-flashing go over the membrane.

Kickout zones. Where a sidewall meets an eave (the spot where kickout flashing is required), the eave course and the sidewall membrane must overlap at the corner so water draining off the wall lands on membrane, not on bare deck.

Low-slope sections. IRC R905.2.2 allows asphalt shingles down to 2:12 but requires double underlayment from 2:12 up to 4:12, and Owens Corning recommends full-deck WeatherLock G on 2:12 to 4:12 shingle roofs. Below 2:12, shingles are not permitted at all, so that section needs a low-slope membrane roof instead.

Brand comparison: the major ice and water shield products

Grace Ice & Water Shield is sold by GCP Applied Technologies, which Saint-Gobain acquired in 2022; GCP’s data sheet cites a track record of more than 35 years. Each major shingle maker also sells its own membrane, which counts toward that maker’s extended system warranty. Values below come from each maker’s data sheet or ICC-ES report; prices are retail listings checked October 19, 2026.

Brand product	Manufacturer	Thickness (mils)	Roll size	Heat rating / max exposure	Retail per roll (Oct 2026)	Source
Grace Ice & Water Shield	GCP (Saint-Gobain)	40	225 sq ft (36 in x 75 ft), 61.4 lb	No number published / 90 days	$179.00 to $251.17	GCP data sheet, Mar 2026
Grace Ice & Water Shield HT	GCP (Saint-Gobain)	40	225 sq ft	260°F / 120 days	$292.83	GCP HT data sheet
Grace Ultra (butyl)	GCP (Saint-Gobain)	30	198 sq ft	300°F / 120 days	$372.00	GCP Ultra data sheet
GAF WeatherWatch (granular)	GAF	40 minimum (ASTM D5147)	150 or 200 sq ft	Not published / 60 days	$80.52 to $99.97	GAF sell sheet RESUL103
GAF StormGuard (film)	GAF	40 minimum (ASTM D5147)	200 sq ft (36 in x 66.7 ft)	250°F / 90 days	$119.00 to $148.94	GAF data sheet RESUL116
Owens Corning WeatherLock G	Owens Corning	53 (OC 2017 data sheet)	200 sq ft (3 ft x 66.7 ft)	Not published / 30 days	$119.00 to $139.00	OC Pub. 10009578-P
Owens Corning WeatherLock Flex	Owens Corning	40	225 sq ft (3 ft x 75 ft)	Not published / 30 days	$189.00	OC Pub. 10009579-O, Dec 2025
Owens Corning WeatherLock Specialty Tile & Metal	Owens Corning	65	214 sq ft	260°F / 180 days	$146.00	OC Pub. 10011679-G, Feb 2025
CertainTeed WinterGuard Granular	CertainTeed	70 nominal	36 in x 65 ft (195 sq ft)	See CertainTeed sheet	$87.95	ICC-ES ESR-1492, Jan 2026
CertainTeed WinterGuard HT	CertainTeed	45 nominal	36 in x 32.5 or 65 ft	See CertainTeed sheet	Not checked	ICC-ES ESR-1492, Jan 2026

Earlier versions of this table listed GAF StormGuard and Owens Corning WeatherLock Flex as 32 to 34 mil budget products. The current documents say otherwise: Owens Corning’s Flex data sheet (Pub. 10009579-O, December 2025) lists 40 mils, and GAF’s StormGuard data sheet RESUL116 gives a 40 mil minimum under ASTM D5147. For a roll-by-roll ranking, see our best ice and water shield comparison.

High-temperature variants for metal roofs

Standard Grace Ice & Water Shield has no published temperature rating, and its data sheet says not to install it under copper, COR-TEN or zinc roofing at high altitude because those metals “can reach extremely high temperatures”; GCP names Grace Ultra for those roofs. The same sheet also notes that “certain product applications are prohibited in hot desert areas in the southwestern United States”. Under a dark metal roof, pick a membrane whose data sheet states a heat rating.

The published ratings are: GAF StormGuard 250°F, Grace Ice & Water Shield HT 260°F with 120 days of allowed exposure, Owens Corning WeatherLock Specialty Tile & Metal 260°F with 180 days, and Grace Ultra 300°F with a 100% butyl adhesive that GCP also lists as compatible with EPDM and TPO tie-ins (the standard sheet is not). Under standing seam panels, also check the panel maker’s installation guide, which often names an approved high-temperature underlayment.

The upcharge for a high-temp variant at the same retailer was $41.66 per roll in October 2026: Home Depot listed Grace Ice & Water Shield at $251.17 and Grace HT at $292.83 for a 225 sq ft roll. Grace Ultra listed at $372.00 for a 198 sq ft roll at Schafer Metals. On a metal roof project, the high-temp membrane is typically run as code-minimum eave coverage and in valleys, with a synthetic underlayment rated for metal over the rest of the deck.

Installation: when in the roof sequence

Ice and water shield is the first weather-resistive layer installed on the deck, going down before any felt or synthetic underlayment. The full sequence:

1. Inspect the sheathing for soft spots, loose fasteners, or rot. Grace’s sheet says the deck must have “no voids, damaged, or unsupported areas” and that dust, loose nails and old roofing must be removed.
2. Install eave drip edge (or after the membrane, if your membrane maker’s sheet says so).
3. Install ice and water shield in valleys first (36-inch strip down the valley centerline), as Grace’s sheet directs.
4. Install ice and water shield at eaves (code-minimum coverage, one or two courses per the table above).
5. Install ice and water shield around penetrations and at sidewalls.
6. Install synthetic underlayment over the rest of the deck, lapping over the top edge of the ice and water shield.
7. Install rake drip edge over the underlayment.
8. Install starter shingles.
9. Install field shingles, step flashing, kickout flashing, ridge cap.

Grace requires the air, deck and membrane to be at 40°F (5°C) or higher, and Owens Corning’s WeatherLock installation instructions say 40°F and rising. Grace also tells installers to cut the membrane into 10 to 15 ft lengths, reroll loosely, and press it in place with heavy hand pressure.

Self-adhered vs torch-down vs nail-down

The peel-and-stick (self-adhered) format is the residential standard. Two other formats exist:

Format	Application	Use case	Code or maker reference
Self-adhered (peel-and-stick)	Strip release liner, press to deck	Residential shingles, metal, slate	ASTM D1970; IRC R905.1.2 “self-adhering polymer modified bitumen sheet”
Two plies cemented together	Two layers of underlayment set in roofing cement	Code alternative where a D1970 sheet is not used	IRC R905.1.2
Torch-down (heat-applied)	Propane torch melts back surface, adheres to deck	Commercial low-slope, parapet walls	Low-slope modified bitumen rules, IRC R905.11

For residential roof replacement, Owens Corning, GAF, CertainTeed and GCP all sell self-adhered D1970 sheets for the eave. Torch-applied sheets bring an open flame onto a wood-framed roof, so they belong to low-slope commercial work. If cold weather forces nailing, Grace’s sheet says to backnail on steep slopes and cover the nails with the next sheet’s lap.

Cost per square installed

The table converts each roll’s October 2026 retail price into a per-square material cost. Labor is quoted separately by roofers; for a standalone small job, Homewyse’s May 2026 national estimate is $6.96 to $8.66 per sq ft including a 2-hour minimum labor charge.

Product	Listed roll price	Roll size	Material per square	Source
GAF WeatherWatch	$80.52 to $99.97	200 sq ft	$40 to $50	Lowe’s; Lakefront Supply, Oct 19, 2026
Owens Corning WeatherLock Mat	$108.00	200 sq ft	$54	Home Depot, Oct 19, 2026
Owens Corning WeatherLock G	$119.00 to $139.00	200 sq ft	$60 to $70	Menards; Lowe’s, Oct 19, 2026
GAF StormGuard	$119.00 to $148.94	200 sq ft	$60 to $74	Woodson Lumber; Builders Warehouse, Oct 19, 2026
Grace Ice & Water Shield	$179.00 to $251.17	225 sq ft	$80 to $112	Schafer Metals; Home Depot, Oct 19, 2026
Grace Ice & Water Shield HT	$292.83	225 sq ft	$130	Home Depot, Oct 19, 2026
Grace Ultra	$372.00	198 sq ft	$188	Schafer Metals, Oct 19, 2026

Worked example. 200 linear feet of eave, 18-inch overhang, 6:12 pitch. The code needs 42 in of horizontal coverage, or 47 in along the slope, so two 36-in courses are required. Two courses x 200 ft x 3 ft = 1,200 sq ft, or 12 squares before laps. At $40 to $112 per square, the membrane alone is $480 to $1,344; at Grace HT’s $130 per square it is $1,560. If the same house had a 6-inch overhang, one course (6 squares) would satisfy the code and the material bill would halve.

Warranty implications: GAF, Owens Corning, CertainTeed positions

Like ridge cap and starter, ice and water shield can count toward the shingle maker’s extended system warranty. The current rules differ by brand:

• Owens Corning Platinum Protection: the August 2026 warranty (Pub. 10020608-O) requires Owens Corning shingles, Owens Corning synthetic underlayment (or a qualifying Owens Corning ice and water barrier over the entire deck), and Owens Corning Hip & Ridge, plus any 2 of 3: an Owens Corning ice and water barrier (WeatherLock, Titanium or RhinoRoof), Owens Corning starter, or VentSure ventilation. It also requires existing roofing, including old ice and water membrane, to be removed. Our WeatherLock review explains how WeatherLock counts toward Owens Corning warranties.
• GAF System Plus, Silver Pledge and Golden Pledge: GAF counts its leak barriers (WeatherWatch, StormGuard) among the qualifying GAF accessories for these enhanced warranties. The number of accessories required and the coverage terms are set in GAF’s current warranty document, so get that document from the roofer before signing.
• CertainTeed SureStart PLUS: CertainTeed ties its stronger coverage to the Integrity Roof System, in which WinterGuard is the ice and water component; check the current warranty for how many system components are required.
• Third-party membranes such as Grace carry their own product warranty but do not count as a shingle maker’s accessory. Owens Corning’s WeatherLock G, Mat and Flex drop to a 5-year warranty when used under another brand’s shingles, per OC Pub. 10009004-C.

Before choosing a cheaper membrane, ask the roofer one question: does this roll appear on the accessory list of the warranty I am buying? If it does not, the saving may cost you the enhanced warranty tier.

Climate-specific recommendations

There is no published, code-based table of coverage by climate. The firm rules are the ones above: IRC R905.1.2 at the eaves where your jurisdiction’s Table R301.2 says yes (24 inches inside the exterior wall line, or 36 inches along the slope on roofs of 8:12 or steeper), the IRC R905.2.8.2 valley options, and the shingle manufacturer’s installation instructions. In cold, snowy areas many roofers extend eave coverage past the minimum and add membrane at valleys and penetrations; in hot climates the membrane is used mainly in valleys and around penetrations against wind-driven rain, and Grace’s data sheet recommends full-deck coverage where wind-driven rain protection is the goal. Treat any wider coverage as a choice to agree in writing with your roofer.

If your house has	Code minimum	Common upgrade to discuss	Membrane pick
Table R301.2 ice barrier “yes”, shingles, 4:12 to 7:12	Eave to 24 in inside wall line (R905.1.2)	Two courses at every eave, valleys	40 mil D1970 sheet matched to shingle brand
Ice barrier “yes”, 8:12 or steeper	24 in inside wall line and 36 in along slope	Extend on north slopes	Same
Shingle sections at 2:12 to under 4:12	Double underlayment (R905.2.2)	Full-deck membrane (OC recommendation for WeatherLock G)	WeatherLock G or equivalent
Dark metal, copper, zinc or COR-TEN panels	Eave rule if “yes”	Heat-rated membrane at eaves and valleys	StormGuard (250°F), Grace HT or OC Tile & Metal (260°F), Grace Ultra (300°F)
Ice barrier “no” (Sun Belt), hurricane exposure	None for ice	Valleys, penetrations, or full deck for wind-driven rain	Check state product approval (Florida) for the roll

When to extend beyond code minimum

The 24-inch past-the-wall rule is a code minimum, not a recommendation for every house. Grace’s data sheet sets the practical target: extend the membrane “above the highest expected level of water back-up from ice dams”. These five situations are where extending coverage is commonly considered; how far to extend is a judgment call to settle with your roofer:

1. Cathedral ceilings or vaulted attics. No attic space separates the heated room from the deck, so roof heat loss reaches the snow directly. Ask the roofer to extend the eave membrane at least one extra 36-inch course on those planes.
2. Inadequate attic ventilation. IRC R806.2 sets a minimum net free vent area of 1/150 of the vented attic floor (1/300 with balanced high and low vents). Older homes with no ridge vent and minimal soffit vents often fall short; extend coverage and fix the vents.
3. Heated gutters or heat cables. If you are running heat cable, you already have an ice problem. Consider extending membrane coverage up the slope.
4. North-facing slopes. A north slope sees little sun, holds snow longer, and refreezes harder. Extended coverage can be limited to the north slope.
5. Wide eave overhangs (24+ inches). The 24-inch point is measured inside the exterior wall line, so a 24-inch overhang already needs 48 inches of horizontal coverage, which is two courses on any pitch.

Extending from 24 inches to 48 inches inside the wall along 200 linear feet of eave adds roughly 400 sq ft, or 4 squares, of membrane (more on steep pitches). At the $40 to $112 per square material range above, that is about $160 to $448 before labor. Compare that with the cost of repairing ceiling insulation, drywall and floors after an ice-dam leak.

Ice and water shield brand product warranties and what they actually cover

The manufacturer warranty on the ice and water shield product itself is separate from the broader system warranty on the roof. Terms vary by product: Owens Corning gives WeatherLock G, Mat and Flex a 5-year limited warranty under non-OC shingles and WeatherLock Specialty Tile & Metal a 30-year limited warranty, per its WeatherLock warranty documents. What these product warranties generally exclude:

• Installation errors (application below 40°F, dirty deck, laps that do not shed water)
• UV exposure past the maker’s limit: 30 days for WeatherLock G, Mat and Flex, 60 days for WeatherWatch, 90 days for Grace Ice & Water Shield and StormGuard, 120 days for Grace HT and Ultra, 180 days for WeatherLock Specialty Tile & Metal
• Punctures from foot traffic or dropped tools
• Movement of the underlying deck (cracked OSB, loose nails)

The system warranty (GAF Golden Pledge, OC Platinum Protection, CertainTeed SureStart PLUS) is what covers the roof as an assembly. OC’s Platinum Protection includes a 25-year workmanship period when a Platinum Preferred Contractor installs and registers the roof, per Pub. 10020608-O.

Common ice and water shield installation mistakes

1. Cold-weather application. Grace and Owens Corning both set 40°F as the minimum for air, deck and membrane. Below that, stage the install for a warmer day rather than relying on nails.
2. Wrinkles and air pockets. Wrinkles create channels that carry water under the membrane. Grace’s method is to cut 10 to 15 ft lengths and press them in with heavy hand pressure.
3. Wrong-direction laps. Upper course must lap over lower (water-shedding direction), at least 3.5 in on side laps and 6 in on end laps for Grace.
4. Skipping the valley. Eave-only coverage is the most common shortcut. IRC R905.2.8.2 requires a valley lining under every shingle valley, and a 36-inch D1970 strip is the permitted membrane option.
5. Bonding to a dirty deck. Dust, sawdust, and old asphalt residue all reduce adhesion. Grace’s sheet calls for priming OSB with Perm-A-Barrier WB Primer if adhesion is marginal.
6. Leaving the membrane exposed too long. Each product has a cover-up limit, from 30 days (WeatherLock G) to 180 days (WeatherLock Specialty Tile & Metal); schedule shingle delivery inside it.

Ice and water shield in the context of a full roof replacement

If your existing roof is 18 to 25 years old and you have had ice dam leaks, the membrane question is part of the replacement scope. Spec the membrane explicitly in the contract: brand name, thickness, square footage of coverage, number of eave courses, and the location list (eaves, valleys, penetrations, sidewalls). Generic language (“ice and water shield as needed”) gives the installer room to use the cheapest product at the minimum coverage. See our guide on choosing a roofing contractor for contract-spec checklists.