Felt vs Synthetic Roof Underlayment: 2026 Comparison Guide

By The Roofing Brief Team. Last reviewed: October 2026.

Synthetic underlayment vs felt comes down to weight, exposure time and warranty: a 10-square roll of Owens Corning ProArmor synthetic weighs 23.5 lb and is rated for up to 90 days of UV exposure, while No. 30 felt (ASTM D226 Type II) must weigh at least 26 lb for every single square and is designed to lie flat for about two weeks uncovered. Both are legal under 2021 IRC Section R905.1.1. Felt no longer wins clearly on price either: October 2026 retail listings put No. 30 felt at $13.50 to $20 per square and 10-square synthetic rolls at about $6 to $12 per square. Synthetic is also the underlayment named in Owens Corning’s Platinum Protection system warranty.

The short answer: 8-criteria comparison

Felt comes in two grades: No. 15 (ASTM D226 Type I, 11.5 lb per square minimum) and No. 30 (Type II, 26 lb per square minimum), per ASTM D226 as summarized by IIBEC. Synthetic underlayment is sold by every major shingle maker; the lines compared below are GAF FeltBuster and Tiger Paw, Owens Corning ProArmor, CertainTeed DiamondDeck and Atlas Summit 60. Our comparison of the best synthetic underlayment brands lists roll prices for each.

Criterion	No. 15 felt	No. 30 felt	Synthetic (example)	Edge	Source
Material cost per square, Oct 2026 retail	$7.50 to $9.24	$13.50 to $20.00	$6.02 to $11.90	Synthetic or No. 15	Google Shopping listings, Oct 19, 2026
Weight	11.5 lb per square min.	26 lb per square min.	2.3 to 4.0 lb per square (FeltBuster, Tiger Paw)	Synthetic	ASTM D226 via IIBEC; ICC-ES ESR-2808
Roll coverage	4 squares (36 in x 144 ft)	2 squares (36 in x 72 ft)	10 squares (ProArmor 42 in x 286 ft, 929 sq ft net)	Synthetic	TAMKO; OC ProArmor data sheet
Tear resistance	Baseline	Baseline	ProArmor: up to 12x felt (ASTM D2261 averages)	Synthetic	OC ProArmor data sheet
Exposure before cover	About 2 weeks (D4869 objective)	About 2 weeks	60 to 180 days by product	Synthetic	IIBEC; maker sheets
Walking surface	Asphalt surface, slick when wet	Asphalt surface, slick when wet	Slip-resistant coating (Tiger Paw, FeltBuster per ESR-2808)	Synthetic	ICC-ES ESR-2808
Code listing	IRC Table R905.1.1(1)	IRC Table R905.1.1(1); required under tile	ICC-ES report (AC188), ASTM D8257	Tie	2021 IRC R905.1.1
System warranty eligibility	Not an OC qualifying underlayment	Not an OC qualifying underlayment	Required for OC Platinum Protection	Synthetic	Owens Corning warranty

Which one to choose

If your job is…	Choose	Rule behind it
A full reroof where the deck may sit uncovered more than 2 weeks	Synthetic rated 90 to 180 days	ASTM D4869 felt targets 2 weeks of exposure; FeltBuster and ProArmor are rated 90 days, Tiger Paw and DiamondDeck 180
Going for an Owens Corning Platinum Protection or GAF Golden Pledge warranty	The shingle maker’s own synthetic	OC requires OC brand synthetic, RhinoRoof U20 or Titanium; Golden Pledge requires a GAF roof deck protection product
Clay or concrete tile	No. 30 felt (D226 Type II) or a tile underlayment listed in the code or an ICC-ES report	2021 IRC Table R905.1.1(1) does not accept D226 Type I under tile
Asphalt shingles in an IRC wind-design area	No. 30 felt, D4869 Type III or IV, or a synthetic with an ESR for high wind	2021 IRC Tables R905.1.1(1) and R905.1.1(3)
A slope of 2:12 to under 4:12	Either, in two layers	2021 IRC Table R905.1.1(2): 19 in head lap on felt; ESR laps for synthetics
A small patch on an existing felt roof, covered the same day	No. 15 or No. 30 felt to match	4 squares or 2 squares per roll; no 10-square roll to buy
Wood shakes (interlayment)	18 in No. 30 felt strips	2021 IRC R905.8.7

What underlayment does (and why it matters)

Underlayment is the layer between the roof deck (typically OSB or plywood sheathing) and the finished roofing (shingles, tile, metal panels), and 2021 IRC Section R905.1.1 requires it under asphalt shingles, tile, metal and the other steep-slope coverings in Chapter 9. It does four jobs:

1. Secondary water barrier. If a shingle is missing, wind-driven, or damaged, underlayment is what keeps water from reaching the deck.
2. Wind uplift resistance. Underlayment is fastened to the deck and resists wind getting under shingles.
3. Surface for shingle nailing. Especially important on OSB decks where nail holding is marginal.
4. Temporary dry-in during construction. The deck is exposed between tear-off and re-shingle. Felt to ASTM D4869 is designed for about 2 weeks of exposure; synthetics are maker-rated for 60 to 180 days.

The choice between felt and synthetic affects all four. The exposure window is the clearest gap: up to 90 days for ProArmor and FeltBuster and 180 days for Tiger Paw and DiamondDeck, against the two-week objective in ASTM D4869 for felt.

#15 felt vs #30 felt (the two felt grades)

“Felt” in roofing means asphalt-saturated felt, an organic or fiberglass mat soaked in asphalt to shed water. The numbers come from the historic weight per 100 sq ft; modern rolls are lighter, so read the ASTM type on the label. The two grades sold in 2026:

#15 felt

• Standard: ASTM D226 Type I, minimum 11.5 lb per square (IIBEC).
• Roll: 36 in x 144 ft, 432 sq ft, 4 squares (TAMKO No. 15 data sheet).
• Price: $29.99 to $36.97 per roll, or $7.50 to $9.24 per square (retail listings, Oct 19, 2026).
• Use case: asphalt shingles at 4:12 and steeper outside wind-design areas, small repairs, outbuildings.
• Not allowed: under clay or concrete tile, per 2021 IRC Table R905.1.1(1).

#30 felt

• Standard: ASTM D226 Type II, minimum 26 lb per square (IIBEC).
• Roll: 36 in x 72 ft, 216 sq ft, about 204 sq ft net once lapped (TAMKO No. 30 data sheet).
• Price: $27.00 to $39.99 per roll, or $13.50 to $20.00 per square (retail listings, Oct 19, 2026).
• Use case: tile roofs, shingle roofs in IRC wind-design areas, wood shake interlayment.
• ASTM D4869 equivalent: Type IV (#26); a D4869 Type II roll is a #13 product, per IIBEC.

Why #30 over #15

If felt is the chosen material, No. 30 carries more than twice the minimum mass of No. 15 (26 vs 11.5 lb per square) and is the only D226 grade the 2021 IRC accepts under tile and in wind-design areas. At October 2026 retail it costs roughly twice as much per square, $13.50 to $20 against $7.50 to $9.24.

Synthetic underlayment construction

Synthetic underlayment is a polypropylene or polyolefin sheet, woven or nonwoven, with a slip-resistant coating. ICC-ES ESR-2808 describes GAF’s three lines this way: Tiger Paw is two nonwoven polyolefin sheets laminated and polymer-coated at 4.0 lb per 100 sq ft, Deck-Armor is two nonwoven polypropylene sheets at 3.7 lb, and FeltBuster is spunbond polypropylene at 2.3 lb, all on 48-inch rolls.

Common synthetic constructions

• Woven scrim with a nonwoven top fabric. Example: Atlas Summit 60, rated for 60 days of UV and -40 F to 240 F (Atlas).
• Spunbond polypropylene. Lighter, entry-level. Example: GAF FeltBuster, 2.3 lb per 100 sq ft (ESR-2808).
• Laminated multi-layer. Example: CertainTeed DiamondDeck, 12 mil multi-layer, 38 lb per 10-square roll, 180-day UV (CertainTeed brochure); GAF Tiger Paw, 4.0 lb per 100 sq ft.
• Self-adhering. Polymer-modified bitumen membranes to ASTM D1970, used as ice barrier and in valleys rather than as field underlayment.

Cost comparison (felt vs synthetic per square, October 2026)

The old rule that felt is the cheap option no longer holds at retail. On October 19, 2026 listings, a 10-square synthetic roll ran $60.15 (Barricade UDL Standard) to $119.00 (Owens Corning ProArmor), or $6.02 to $11.90 per square, against $13.50 to $20.00 per square for No. 30 felt. Installed, HomeGuide’s underlayment replacement guide (April 2024) puts felt materials at $0.05 to $0.15 per sq ft and labor at $0.65 to $3.20 per sq ft, so labor, not the roll, drives the underlayment line.

Underlayment	Roll	Listed price	Per square	Rolls for 25 squares	Source
No. 15 felt	4 squares	$29.99 to $36.97	$7.50 to $9.24	7	Google Shopping listings, Oct 19, 2026, compiled in our roofing felt price guide
No. 30 felt	2 squares (204 sq ft net)	$27.00 to $39.99	$13.50 to $20.00	13
Barricade UDL Standard synthetic	10 squares	$60.15	$6.02	3
Owens Corning ProArmor	10 squares (929 sq ft net)	$119.00	$11.90	3

Worked example, 2,500 sq ft (25-square) roof at 4:12 or steeper: 7 rolls of No. 15 felt cost $209.93 to $258.79, 13 rolls of No. 30 cost $351.00 to $519.87, and 3 rolls of synthetic cost $180.45 to $357.00 at the listed prices. Below 4:12 the felt count roughly doubles because IRC Table R905.1.1(2) laps each 36-inch sheet 19 inches. Cap nails, drip edge and ice barrier are separate lines.

Tear resistance (ProArmor: up to 12x felt)

Tear resistance is the main practical difference on the roof. Owens Corning’s ProArmor data sheet claims up to 12 times the tear strength of felt, based on averaged ASTM D2261 tear tests. In practice that shows up in three places:

• Felt can tear around fasteners when wind lifts a loose sheet before shingles go on.
• Felt tears under foot traffic, especially on hot or wet days.
• Synthetic resists rips around cap fasteners, which is why ESR-2808 and maker instructions call for caps on GAF synthetics.

Where shingles blow off in a wind event, the underlayment becomes the only layer shedding water until the roof is repaired. That is why the 2021 IRC requires No. 30 felt, ASTM D4869 Type III or IV, or an equivalent synthetic cap-nailed on a 12-inch grid in wind-design areas (Table R905.1.1(3)).

Water resistance and wrinkling

Felt is an asphalt-saturated mat. It sheds water, and ASTM D4869 felt must pass a liquid-water transmission test, per IIBEC, but the mat can wrinkle when it gets wet and dries, which telegraphs through shingles. Synthetics are polymer sheets that do not absorb water; Atlas lists Summit 60 as water resistant and states it will not buckle, warp or crack. Neither product is a waterproof membrane; that role belongs to ASTM D1970 ice barrier.

The practical consequence: if a reroof gets rained on after tear-off, wrinkled felt may need to be pulled and replaced before shingles go down so the courses lie flat. Synthetic within its rated exposure window (60 to 180 days by product) is dried off and the work continues.

Walkability and slip resistance

Felt has an asphalt surface with no slip coating, and it gets slick when wet with rain, dew or frost. Fall protection on residential roofs is governed by OSHA’s construction standard 29 CFR 1926.501(b)(13), which requires fall protection for work 6 feet or more above a lower level, whichever underlayment is used.

Synthetic lines add a slip-resistant coating: ICC-ES ESR-2808 describes one on the back of Tiger Paw and FeltBuster, and Atlas applies one to the bottom of Summit 60 with a nonwoven top for footing. Slip coatings help, but they do not replace the harness and anchor that OSHA requires at 6 feet.

UV exposure (synthetic 60 to 180 days, felt about 2 weeks)

UV tolerance matters during the window between tear-off and the final shingle. Felt data sheets carry no UV rating; the ASTM D4869 objective, quoted by IIBEC, is felt that stays flat for two weeks exposed. Synthetic makers publish a number:

Product	Maker’s UV or exposure limit	Weight	Source
GAF FeltBuster	90 days	2.3 lb per 100 sq ft	GAF installation instructions; ESR-2808
GAF Tiger Paw	180 days	4.0 lb per 100 sq ft	GAF data sheet RESUL179; ESR-2808
Owens Corning ProArmor	90 days	23.5 lb per 10-square roll	OC ProArmor data sheet
CertainTeed DiamondDeck	180 days	38 lb per 10-square roll	CertainTeed DiamondDeck brochure
Atlas Summit 60	60 days	10-square roll	Atlas product page
No. 15 or No. 30 felt	No UV rating; D4869 targets 2 weeks	11.5 or 26 lb per square min.	IIBEC

For most reroofs the shingles go on within days, so the gap rarely matters. It matters when weather, supply delays or a staged job leave the deck covered only by underlayment for more than two weeks; past the maker’s limit, the exposed sheet should be replaced or covered.

Lifespan and warranty terms

Underlayment has no ASTM service-life rating, so the useful comparison is warranty paper. ProArmor carries a 10-year limited product warranty on its own, per Owens Corning’s data sheet. Installed as part of an Owens Corning system, it is covered under the system warranty: during the first 25 years of the Platinum Protection Workmanship Period, Owens Corning covers application defects on a single-family home installed by a Platinum Preferred Contractor.

Underlayment	Stand-alone coverage	System coverage path	Source
Owens Corning ProArmor	10-year limited	Platinum Protection: 25-year workmanship period	OC data sheet; OC warranty
GAF FeltBuster, Tiger Paw, Deck-Armor	Covered as GAF accessories	Golden Pledge: non-prorated misapplication coverage of 25 or 30 years, per GAF	GAF warranty comparison guide
Generic No. 15 or No. 30 felt	Usually none beyond ASTM compliance	Not an Owens Corning qualifying underlayment	OC warranty

The synthetic-outlasts-the-shingles argument is about avoiding a weak layer under a 25 to 30 year architectural shingle; ask the roofer which underlayment the shingle maker’s system warranty names. See our asphalt shingle roof lifespan guide for the shingle-side math.

Code requirements (IRC R905.1.1)

The 2021 International Residential Code Section R905.1.1 sets the legal minimum. Table R905.1.1(1) lists ASTM D226 Type I or II felt, ASTM D4869 Type I to IV felt, and ASTM D6757 underlayment for asphalt shingles. Synthetics are accepted as alternatives through ICC-ES evaluation reports under acceptance criteria AC188; ESR-2808, for example, covers GAF’s three synthetics as alternatives to D226 and D4869 under the 2006 to 2024 IRC. The 2024 IRC adds ASTM D8257 (synthetic) and ASTM D1970 directly to Table R905.1.1(1).

Code requirements summary

• Roof slope 2:12 to under 4:12: two layers of underlayment (felt: 19-inch eave strip, then 36-inch sheets lapped 19 inches), per Table R905.1.1(2).
• Roof slope 4:12 or greater: one layer, felt lapped 2 inches at the head and 4 inches at the ends; ESR-2808 calls for 3-inch head and 6-inch end laps on GAF synthetics.
• Ice barrier: where ice damming is a local hazard, from the eave to at least 24 inches inside the exterior wall line, per R905.1.2.
• Fasteners: in wind-design areas, ring or deformed shank nails with 1-inch caps on a 12-inch grid, 6 inches at laps, per Table R905.1.1(3); elsewhere, “fastened sufficiently to hold in place” plus the maker’s instructions and ESR.
• Minimum slope for synthetics: ESR-2808 limits GAF’s synthetics to roofs of 2:12 or steeper with ventilated attics.

Code is the floor. Manufacturer system warranties add requirements on top, such as Owens Corning’s rule that Platinum Protection roofs use Owens Corning brand synthetic, RhinoRoof U20 or Titanium underlayment.

Brand comparison

The synthetic lines below are listed with values from the maker’s sheet or ICC-ES report. Prices are retail roll listings from our October 2026 checks, which change weekly.

Product	Manufacturer	Construction or weight	UV rating	Roll	Source
FeltBuster	GAF	Spunbond polypropylene, 2.3 lb per 100 sq ft	90 days	48 in wide	ESR-2808; GAF instructions
Tiger Paw	GAF	Two laminated nonwoven polyolefin sheets, 4.0 lb per 100 sq ft	180 days	48 in wide	ESR-2808; GAF RESUL179
Deck-Armor	GAF	Two nonwoven polypropylene sheets, breathable, 3.7 lb per 100 sq ft	180 days	48 in wide	ESR-2808
ProArmor	Owens Corning	23.5 lb per roll; meets ASTM D8257, D226 Type II, D4869 Type IV	90 days	42 in x 286 ft, 929 sq ft net	OC ProArmor data sheet
DiamondDeck	CertainTeed	12 mil multi-layer, 38 lb per roll	180 days	48 in x 250 ft	CertainTeed brochure
Summit 60	Atlas	Woven polymeric scrim; ASTM D8257, D6757	60 days	10 squares	Atlas product page

GAF FeltBuster vs Tiger Paw

Both are GAF roof deck protection under ICC-ES ESR-2808, but they are different sheets. Tiger Paw weighs 4.0 lb per 100 sq ft against FeltBuster’s 2.3 lb, carries a 180-day UV rating against 90 days, and ESR-2808 evaluated Tiger Paw (and Deck-Armor) as a component of Class A shingle assemblies over 3/8-inch plywood, while it limits FeltBuster to areas where non-classified roof coverings are permitted. If your jurisdiction requires a Class A roof assembly, ask the roofer to show the listing for the exact underlayment on the quote.

System matching

Owens Corning’s Platinum Protection warranty requires Owens Corning shingles plus Owens Corning brand synthetic underlayment, RhinoRoof U20 or Titanium synthetic (OC warranty document). GAF’s Golden Pledge requires a GAF roof deck protection product among its accessory categories, and CertainTeed lists DiamondDeck and RoofRunner as the underlayments in its roof system guidance. A generic felt roll from another maker does not meet any of these system requirements.

For brand-specific shingle reviews, see our GAF Timberline HDZ review, Owens Corning Duration review, and CertainTeed Landmark review.

Ice and water shield (a different product, often used with both)

Ice and water shield (also called peel-and-stick underlayment) is a self-adhering polymer-modified bitumen membrane to ASTM D1970, related to modified bitumen roofing. It is not a substitute for field underlayment; it goes where the 2021 IRC or the shingle maker calls for an ice barrier or valley lining.

Where to use ice and water shield

• Eaves: from the eave to at least 24 inches inside the exterior wall line where ice damming is a local hazard (2021 IRC R905.1.2).
• Closed valleys: an ASTM D1970 membrane at least 36 inches wide is permitted as the valley lining (2021 IRC R905.2.8.2).
• Penetrations and roof-to-wall joints: per the shingle maker’s installation instructions; system warranties such as Golden Pledge name leak barrier locations.
• Low-slope sections: below 4:12, two layers of field underlayment are the code minimum, or ASTM D1970 self-adhering underlayment under the R905.1.1 exception.

Cost

Ice and water shield is priced by the roll, typically 2 squares per roll versus 10 for synthetic field underlayment, so it costs far more per square. Price only the linear footage of eaves (24 inches inside the wall line) and the valleys (36-inch width) on the quote, and ask the roofer to list the brand and roll count.

Installation differences (felt vs synthetic)

The two materials fasten differently. Felt is commonly attached with roofing nails or staples outside wind-design areas, while GAF’s ESR-2808 and Owens Corning’s instructions call for cap fasteners on their synthetics, and the 2021 IRC requires cap nails on a 12-inch grid for any underlayment in wind-design areas. Our ranking of the best cap staplers for roofing underlayment compares the tools that drive those caps.

Felt install

• Rolled out horizontally starting at the eave, parallel to it.
• At 4:12 and steeper, each course laps the one below by 2 inches, with 4-inch end laps (IRC Table R905.1.1(2)).
• From 2:12 to under 4:12, a 19-inch starter strip, then 36-inch sheets lapped 19 inches.
• No. 15 rolls cover 4 squares; No. 30 rolls cover 2 squares.

Synthetic install

• Rolled out horizontally starting at the eave, printed side up.
• GAF synthetics: 3-inch head laps and 6-inch end laps (ESR-2808).
• ProArmor: 929 sq ft of net coverage per roll with 3-inch overlaps.
• Fastened per the maker’s instructions, and with cap nails on a 12-inch grid in IRC wind-design areas.
• One 10-square roll replaces five rolls of No. 30 felt.

The labor effect follows from roll size: a 25-square roof takes 3 synthetic rolls against 13 rolls of No. 30 felt, so fewer trips up the ladder and fewer end laps. No public time study quantifies the savings, so treat contractor claims of a set percentage as marketing.

Fastener selection

Underlayment fasteners are a small line item that decides whether the sheet survives wind before the shingles go on. The rules by fastener type:

Fastener	Used with	Rule	Source
Roofing staples	Felt	Not permitted for underlayment in IRC wind-design areas	2021 IRC Table R905.1.1(3)
Smooth roofing nails	Felt	Maker’s instructions outside wind-design areas	Felt data sheets
Plastic cap nails	Synthetic; any underlayment in wind-design areas	12-inch grid in wind-design areas	2021 IRC Table R905.1.1(3)
Plastic cap staples	Synthetic, where the ESR allows	Check the ESR and the maker’s instructions	ICC-ES report for the product

Ask the roofer which fastener the underlayment’s ESR or installation instructions name, and whether your address falls in an IRC wind-design area under Figure R301.2.1.1. Staples on a synthetic that calls for caps are a common reason a sheet tears loose before shingles go down.

Synthetic vs felt in specific applications

Steep slopes (over 12:12)

Steep slopes make footing the main concern, and synthetic’s slip-resistant coating helps crews on the sheet. Above 21:12, 2021 IRC R905.2.6 requires shingles to be attached per the maker’s special steep-slope instructions, which can also govern the underlayment fastening.

Low slopes (2:12 to 4:12)

Low slopes require two layers of underlayment per IRC Table R905.1.1(2), regardless of material. With felt that means a 19-inch head lap on every 36-inch sheet; with a synthetic, the ESR sets the lap (for some products, to the centerline of the course below). The 2021 IRC R905.1.1 exception also allows ASTM D1970 self-adhering underlayment in place of the two layers when installed per both the underlayment and shingle makers’ instructions.

Metal roofing

Standing seam metal roofs get hot, and asphalt-based felt can soften and stick to panels, so most panel makers specify a synthetic or a high-temperature self-adhered underlayment. Atlas, for example, rates Summit 60 from -40 F to 240 F; match the rating to the panel maker’s spec. See our standing seam metal roof cost guide.

Tile and slate

Concrete tile, clay tile and slate outlast most underlayments, so the underlayment choice sets the reroof date. Under clay and concrete tile, 2021 IRC Table R905.1.1(1) accepts ASTM D226 Type II felt, ASTM D2626 Type I, or ASTM D6380 Class M roll roofing; a synthetic needs an ICC-ES report that lists tile use.

When felt still makes sense

Felt isn’t obsolete. Three jobs still favor it, each tied to a code rule or a roll-size fact:

1. Small repairs and patch-ins

A patch on an existing felt roof needs only part of a 4-square No. 15 roll ($29.99 to $36.97 at October 2026 retail) or a 2-square No. 30 roll, and matches the surrounding layer. Buying a 10-square synthetic roll for a 1-square repair wastes most of it.

2. Low-slope sections with full ice and water shield coverage

When a low-slope section (2:12 to under 4:12) gets full ASTM D1970 ice barrier coverage, the field underlayment becomes a backup layer, and No. 30 felt meets code there.

3. Tile roof applications and shake interlayment

Under clay and concrete tile, the 2021 IRC names No. 30 (D226 Type II) felt directly in Table R905.1.1(1), and wood shakes need 18-inch No. 30 felt interlayment under R905.8.7. A synthetic must show an ICC-ES report listing tile use to replace it.

Manufacturer warranty requirements

System warranties are where synthetic pulls ahead for owner-occupied homes, because the top tiers name the maker’s own underlayment. The three majors:

GAF Golden Pledge

Requires GAF shingles plus GAF accessories in each category, including Roof Deck Protection (FeltBuster, Tiger Paw or Deck-Armor) and Leak Barrier (such as StormGuard or WeatherWatch), installed by a GAF Master Elite contractor. GAF describes the non-prorated misapplication coverage as 25 or 30 years.

Owens Corning Platinum Protection

Requires Owens Corning shingles and Owens Corning brand synthetic, RhinoRoof U20 or Titanium underlayment, installed and registered by a Platinum Preferred Contractor. For a single-family home, workmanship coverage runs the first 25 years of the Platinum Protection Workmanship Period, per the OC warranty document.

CertainTeed Integrity Roof System

CertainTeed’s Integrity Roof System pairs its shingles with CertainTeed underlayment (DiamondDeck or RoofRunner) and WinterGuard ice and water barrier. SureStart PLUS coverage is tied to that system and a CertainTeed credentialed contractor; get the current warranty sheet from the contractor.

The pattern: top-tier warranties from all three majors name the maker’s own underlayment, and Owens Corning’s names only synthetics. A generic felt roll limits a roof to the base shingle warranty.

For a cost-and-weight version of this comparison focused on felt grades, see our roofing felt vs synthetic underlayment guide.