Class 4 impact-resistant shingles pass the UL 2218 steel-ball drop
test (a 2-inch steel ball dropped from 20 ft) without cracking the
mat. They cost ~$2,000-$3,500 more on a typical NAZ re-roof.
Six AZ homeowners-insurance carriers offer discounts for Class 4.
Current (April 2026) discount structures:
The carrier-by-carrier 2026 table
| Carrier | Wind/hail discount | Required documentation |
|---------------|--------------------| -----------------------|
| State Farm | 28% | Manufacturer cert + invoice |
| Allstate | 25% | Manufacturer cert |
| Farmers | 22% | Manufacturer cert + photos |
| American Family | 20% | Manufacturer cert + permit |
| Liberty Mutual| 17% | Manufacturer cert |
| USAA | 15% | Manufacturer cert + invoice |
Discount applies only to the wind/hail line of your premium, not
the full premium. Typical AZ premium for a $400K home: $1,800/year,
of which ~$650 is wind/hail. A 25% discount on $650 = $163/yr.
Over 25 years: ~$4,075 in premium savings.
Approved Class 4 shingle SKUs
- GAF Timberline AS II — most-installed in AZ
- Owens Corning Duration Storm — second-most
- CertainTeed Landmark Storm — third
- Atlas StormMaster Shake — premium look
- IKO Nordic — uncommon in AZ but available
Avoid "impact-resistant" labels without UL 2218 Class 4 certification
— some lower-grade shingles claim "storm-resistant" without passing
the drop test, and insurers won't honor them.
How to claim the discount
- Tell your contractor before installation — they have to use
the right SKU + provide manufacturer cert.
- Save the manufacturer Class 4 certificate — usually a
single-page letter on manufacturer letterhead.
- Submit to your insurance agent within 30 days of completion.
- Confirm in writing — the discount should appear on your
next renewal.
Some carriers backdate the discount to the install date — ask.
Catch: roof age + Class 4 reset
Some carriers reset their roof-age clock on a Class 4 install. So a
20-year-old roof being replaced with Class 4 in 2026 starts a
fresh "year 0" for premium calculation purposes.
Other carriers (less common) phase out the Class 4 discount as
your roof ages — read your renewal carefully.