Impact Ratings Explained
Class 3 vs. Class 4 Impact-Resistant Shingles: What Is the Difference?
UL 2218 is Underwriters Laboratories' impact-resistance test for roofing materials, and Class 4 is the highest classification it awards. Here's exactly how the test works, which current products fall into each class, and what the rating doesn't promise.
UL 2218 Explained · Not A Hail-Proof Guarantee · Middle Tennessee Roofing Experts
Quick Answer
What's the difference between Class 3 and Class 4 shingles?
UL 2218 is Underwriters Laboratories' impact-resistance test for roofing materials. Class 4 is the highest impact-resistance classification available under UL 2218. The test uses prescribed steel-ball sizes and heights intended to represent specified impact-energy levels, but does not reproduce all physical properties or damage modes of natural hail — 1.75 inches for Class 3, 2.00 inches for Class 4. Each test location receives two prescribed impacts at the same test area.
Cosmetic denting and granule loss are not scored as the primary UL 2218 failure criterion; pass/fail evaluation focuses on prohibited cracks, tears, or fractures visible on the back surface after testing. Malarkey's Highlander AR is Class 3; Vista AR, Legacy, and Windsor are Class 4. GAF's Timberline HDZ is Class 3; Timberline AS II is Class 4.
A Class 3 or Class 4 rating is not itself a warranty against hail damage — review the specific manufacturer warranty issued for the selected product and system.
How The Test Works
How does UL 2218 testing actually work?
A steel ball is dropped from a prescribed height
UL 2218 uses prescribed steel-ball sizes and heights intended to represent specified impact-energy levels for Class 1 through Class 4 (1.25", 1.50", 1.75", 2.00"). This does not reproduce all physical properties or damage modes of natural hail.
Each test location takes two impacts
Each test location receives two prescribed impacts at the same test area.
Technicians examine the underside
Technicians examine the underside of the shingle for cracking, tearing, or splitting.
Pass/fail is based on back-surface damage only
If there's no cracking, tearing, or splitting visible from below, the shingle passes — regardless of visible surface marks.
Side By Side
Class 3 vs. Class 4, at a glance
Class 3 shingles are tested with a 1.75-inch steel ball from 17 feet; Class 4 shingles with a 2.00-inch ball from 20 feet.
| Class 3 | Class 4 | |
|---|---|---|
| Steel ball size | 1.75 in | 2.00 in |
| Drop height | 17 ft | 20 ft |
| Malarkey products | Highlander AR | Vista AR, Legacy, Windsor |
| GAF products (examples, not exhaustive) | Timberline HDZ | Timberline AS II |
| Fails for | Cracking, tears, fractures on back surface | Same |
| Not the primary failure criterion | Surface dents, granule loss | Same |
GAF examples are featured in Mr. GoodRoof's current comparison, not a complete list of every GAF impact-rated product. Always verify the specific package.
Set The Right Expectation
Does Class 4 mean the shingle can't be damaged by hail?
Class 4 is not a hail-proof guarantee.
Cosmetic denting and granule loss are not scored as the primary UL 2218 failure criterion — the test focuses on prohibited cracks, tears, or fractures visible on the back surface. A Class 4 roof can still show visible hail marks after a storm without that meaning the shingle "failed" the test it earned. Review the warranty issued for the selected product and roofing system.
Impact Rating Isn't Everything
Does Class 4 mean better in every way — and does it affect insurance?
Does Class 4 mean the shingle is better in every way?
No. Impact class says nothing about color, algae protection, wind-warranty path, asphalt formulation, or price.
Can impact class affect insurance?
Some carriers may offer a credit for qualifying impact-resistant roofs, but eligibility is carrier- and policy-specific. See our Class 4 insurance discount page.
A Different Test Method
How is UL 2218 different from IBHS hail testing?
IBHS uses laboratory-manufactured hailstones and evaluates dents, tears, and granule loss to compare relative performance among products — a different methodology than UL 2218's steel-ball classification test.
Get Started
Not sure which impact class fits your home?
A Mr. GoodRoof project manager can walk your roof and compare Class 3 and Class 4 options against your budget, insurance considerations, and priorities.
- Free on-site roof evaluation
- Side-by-side product comparison for your home
- Certified installation across Malarkey's product lines
- Straightforward guidance — no pressure to upgrade
Get a Free Roofing Estimate
Class 3 vs. Class 4 FAQs
Frequently asked questions
Is Class 4 the highest UL 2218 rating?
Yes — Classes 1 through 4, with 4 the highest impact-resistance classification available.
Does Class 4 mean no hail damage?
No — a Class 3 or Class 4 rating is not itself a warranty against hail damage.
Is Class 3 worth considering?
Yes — a meaningful impact tier and often a lower-cost step up from unrated products.
Are all shingles in a product family rated the same?
Not necessarily — verify the specific package.
Should I choose a roof by impact rating alone?
No — compare the full system, wind and algae coverage, appearance, and warranty path too.
Keep Reading
Related roofing & shingle resources
Sources
Where this information comes from
- IBHS Relative Impact Resistance of Asphalt Shingles
- Malarkey Highlander AR
- Malarkey Shingles Overview
