GAF Timberline AS II Review: Is It the Right Class 4 Shingle for Minnesota? (2026)

GAF Timberline AS II is a polymer-modified asphalt architectural shingle with a UL 2218 Class 4 impact rating, the highest hail rating available on a residential roof. For Minnesota homeowners replacing a roof after hail, it's one of three serious options to consider, alongside CertainTeed Landmark Impact and Owens Corning Duration Storm. In the Twin Cities it lands at roughly $21,000 to $28,000 installed on a typical 2,000–2,400 sq ft home, and it unlocks a 10–25% insurance discount on most MN carriers.

What Exactly Is GAF Timberline AS II?

Timberline AS II is GAF's newer-generation Class 4 architectural shingle, built to replace the older Timberline ArmorShield II that many Minnesota homeowners had on their previous roof. The "AS" stands for ArmorShield; the "II" simply differentiates it from the discontinued first-generation product. It is part of the broader Timberline HDZ family, but with a polymer modifier engineered into the asphalt mat to absorb impact rather than crack under it.

The standard architectural Timberline HDZ is a fine shingle, it's the most-installed shingle in North America for a reason, but it carries no impact rating. AS II is the upgrade that turns the same shingle silhouette into a Class 4 product. The dimensional shadow line, the color palette breadth, the install pattern, and the LayerLock nailing zone are all the same. The difference is in the chemistry of the asphalt itself.

What Does "UL 2218 Class 4" Actually Mean for a Twin Cities Roof?

UL 2218 is the impact-resistance test administered by Underwriters Laboratories. The shingle is mounted to a standard deck and struck by a 2-inch hardened steel ball dropped from 20 feet, roughly the impact equivalent of a 2-inch hailstone. To earn Class 4, the shingle mat cannot split, crack, or rupture on either side after two strikes in the same spot. Class 3 uses a 1.75-inch ball, Class 2 a 1.5-inch ball, Class 1 a 1.25-inch ball.

What that means in a real Minnesota storm: a Class 4 shingle is not hail-proof. Nothing in residential roofing is. A 3-inch hailstone hitting at terminal velocity from a supercell will still bruise the granule layer. But the underlying asphalt mat won't fracture, and that's what creates leak pathways. In the storms I see across the Twin Cities, a Class 4 roof might still show cosmetic damage and become an insurance claim, but it will rarely become a leaking-roof emergency in the same way a standard shingle can.

This is also why Class 4 is the only impact rating that triggers a meaningful homeowner insurance discount in Minnesota. Carriers know the structural shingle is intact.

How Does the StrikeZone Polymer Composition Work?

GAF builds AS II on what it calls StrikeZone technology, an SBS-modified (styrene-butadiene-styrene) polymer blended directly into the asphalt during manufacturing. SBS is the same rubber compound used in commercial modified-bitumen flat roofs and high-end residential shingles across the industry. What it does is give the asphalt elasticity. When a hailstone hits, the shingle deforms slightly and rebounds instead of fracturing the way standard asphalt does.

The compound also handles Minnesota's freeze-thaw cycles better than standard asphalt. Standard asphalt gets brittle below about 25°F. SBS-modified asphalt stays flexible into single digits. For a Twin Cities homeowner that translates into fewer wind-driven cracks at the edges and longer effective shingle life through year 12, 15, 20, the window where standard shingles in our climate start showing their age.

The trade-off: SBS-modified shingles are slightly heavier and slightly more expensive to manufacture. That's part of why the AS II premium over standard Timberline HDZ is real, not invented.

What Colors Does GAF Timberline AS II Come In?

GAF stocks Timberline AS II in a narrower palette than the standard HDZ line, usually 7 to 9 colors at any given Twin Cities distributor (Roof Depot, ABC Supply, SRS Distribution). Stock varies by year, but the consistent staples are:

• Charcoal
• Pewter Gray
• Weathered Wood
• Barkwood
• Hickory
• Slate
• Shakewood
• Birchwood

If you specifically want a deep red, deep brown, or any of the more designer-tier blends that the standard HDZ comes in (Hunter Green, Mission Brown, Patriot Red), you may need to compromise. This is the single most common reason a homeowner switches from AS II to CertainTeed Landmark Impact at the contract stage. CertainTeed simply offers more color depth in the Class 4 product line.

For most Twin Cities exteriors, the AS II palette covers what works. Pewter Gray, Charcoal, and Weathered Wood are the three I install most often.

What Are the GAF Warranty Tiers, and Which One Actually Applies to AS II?

This is where most homeowners get confused, because GAF markets the shingle and the warranty as if they're inseparable. They aren't. The shingle is the shingle. The warranty depends on the contractor's certification level with GAF.

Two things matter here. First, the headline "Lifetime" warranty most homeowners see in the brochure is the entry-level coverage. It does not include labor or tear-off if a material defect is found in year 18. Second, only a Master Elite contractor can offer the Golden Pledge. Master Elite is GAF's highest tier and is awarded based on contractor longevity, customer reviews, financial stability, and installer training. Only the top 2 percent of GAF-authorized contractors qualify.

Disclosure: Northern Forge Construction is a GAF Certified contractor (Silver Pledge tier), not Master Elite. If you specifically want the Golden Pledge warranty on your roof, I'll tell you straight: ask me for a referral to a Master Elite firm I trust in the Twin Cities, or I'll partner with one on the project. Most homeowners I write are well-served by the Silver Pledge (it covers material, workmanship, and tear-off) but if you have an HOA that requires Golden Pledge documentation or you simply want the strongest paper, that's a real reason to pick a different installer or a partnered arrangement.

What Does GAF Timberline AS II Cost Installed in the Twin Cities in 2026?

On a typical 2,000–2,400 sq ft Twin Cities home with a single layer tear-off, moderate complexity (6–8 pitch, 1 to 2 valleys, 2 to 3 penetrations), and full code-compliant install, here's what I see GAF Timberline AS II land at in 2026:

Class 4 carries a premium of roughly $1,500 to $3,000 on a typical home compared to a standard architectural Timberline HDZ install. For most Minnesota homeowners with an annual roof premium of $1,200 to $2,000, the 10–25% insurance discount recovers that premium within 5 to 8 years, and you're net-positive for the rest of the roof's life. Compare that against the full 2026 Minnesota roof replacement cost guide for context.

GAF Timberline AS II vs CertainTeed Landmark Impact vs Owens Corning Duration Storm

These three are the Class 4 trio I quote against each other most often in the Twin Cities. None of them is universally "best." Here's the honest head-to-head:

For more depth, see the full three-way comparison.

Who Is GAF Timberline AS II Best For?

Pick AS II if:

• You're in a known Twin Cities hail corridor (Blaine, Coon Rapids, Andover, Maple Grove, Plymouth, Brooklyn Park) and want the highest impact rating available.
• You want the most well-known and resold shingle brand, important if you may sell within 5–10 years and a buyer's inspector is going to recognize the name.
• You have access to a GAF Master Elite contractor and want the Golden Pledge warranty.
• The colors in the AS II palette work for your exterior. Pewter Gray, Charcoal, Weathered Wood, Barkwood are the strongest matches for typical MN siding.
• Your insurance is offering a Class 4 discount and you want to lock that in.

Who Should Pick an Alternative?

Skip AS II (and look at CertainTeed Landmark Impact, OC Duration Storm, or even standard Timberline HDZ) if:

• You want a designer color not in the AS II palette (deep red, hunter green, specialty browns). CertainTeed Landmark Impact has more depth.
• The install is happening in cold weather (October–March). CertainTeed Landmark Impact's SBS-modified mat is the most flexible of the three in single-digit temperatures.
• You're in a low-hail micro-zone (some pockets of central Hennepin, parts of Ramsey County) where the historical claim frequency doesn't justify the Class 4 premium. A standard Timberline HDZ at $17,000–$22,000 installed may make more financial sense.
• You specifically need Golden Pledge and your preferred contractor isn't Master Elite. Don't downgrade the warranty just to use a particular installer. Find the right pairing.
• Your insurance carrier is non-renewing the roof regardless of upgrade. Some carriers (older roofs hit it hardest) are pulling out of MN entirely; if that's your situation, see our piece on roof-age non-renewal first.

The shingle is excellent. The decision still depends on color, cold-weather scheduling, installer certification, and your carrier's discount math, not on the shingle alone.

What Voids the GAF Warranty?

A few things will quietly invalidate the warranty regardless of which tier you're at:

• Inadequate ventilation: soffit intake plus ridge or off-ridge exhaust must meet the 1:150 net free area ratio (or 1:300 with balanced intake/exhaust). GAF inspectors check this on every claim.
• Mixing non-GAF system components at the higher tiers: Silver and Golden Pledge require GAF underlayment, GAF starter, GAF hip-and-ridge, GAF ventilation.
• Re-roof over existing layers at the Lifetime tier: anything other than a full tear-off forfeits the upgrade tiers.
• Improper nailing: high or angled nails outside the LayerLock zone are the #1 install error that voids material claims when one is filed in year 8 or year 15.
• Owner modifications: adding a vent stack or solar penetration without re-flashing per GAF spec voids local coverage.

This is one place a real installer pays for themselves. I include a venting calc, a photo record of the LayerLock nailing pattern on every plane, and a Certificate of Completion with the GAF system components itemized, which is what the carrier and GAF both look for if a warranty claim ever has to be filed.

Will It Help Me on My Next Insurance Claim?

Yes, in three ways. First, the discount on next year's premium, usually 10–25% of the roof line on the policy. Second, on a future claim, the Class 4 shingle is more likely to survive borderline hail without becoming a full replacement claim, which protects your loss history. Third, when a claim does happen, the documentation showing a Class 4 product is in place often shortens the adjuster conversation considerably.

If you already have an open claim, see our guides on recoverable depreciation and the broader Minnesota insurance claim guide. Picking the right shingle is one decision, and getting the full check from the carrier is a separate one.

Frequently Asked Questions

Northern Forge Construction is a Coon Rapids–based, GAF Certified roofing contractor serving the Twin Cities metro. MN Licensed BC809688. Owner Luis Hernandez is on every job site. This article is informational and does not represent a manufacturer endorsement; warranty terms are summarized. Refer to GAF's published warranty documents for full coverage details.