What “Class 4” actually means
“Class 4” refers to the highest rating in UL 2218, a lab test for roof covering impact resistance. Steel balls of increasing size are dropped from set heights onto shingles installed on a deck, twice in the same spot:
- Class 1: 1¼-inch ball
- Class 2: 1½-inch ball
- Class 3: 1¾-inch ball
- Class 4: 2-inch ball
To pass, the shingle cannot crack on the top surface or the underside. Manufacturers achieve this with rubber-modified (often SBS) asphalt that flexes on impact, or with reinforced backing.
When you compare products, ask for the exact product’s Class 4 listing. Marketing terms like “hail-resistant” or “tough” are not ratings.
The case for Class 4 in Calgary
Calgary gets hit often. Since 2020, major hailstorms have struck in 2020, 2021, 2024 and 2025. The Insurance Bureau of Canada says Alberta has had at least one major hailstorm every year for two decades. A roof with a 25- to 30-year rating may face several significant storms in its life here.
Fewer leaks and less hassle. Even when insurance pays for a new roof, a claim means inspections, adjuster visits, waiting for crews, and sometimes interior water damage.
Possible premium discounts. Some Alberta insurers discount premiums for Class 4 roofs. The size of the discount is not standardized. A study done by MNP for the Insurance Bureau of Canada estimated that homeowners in high-risk hail areas who install hail-resistant roofing and siding could reduce premiums by as much as half. Your insurer’s actual discount is what matters, so ask.
Resale. In hail-prone Calgary neighbourhoods, an impact-resistant roof is a selling point buyers increasingly ask about.
The case against (or for waiting)
- You usually pay the difference. Insurance replaces like with like. If your current roof is standard architectural shingles, the upgrade is out of pocket.
- No rebate right now. The City of Calgary’s $3,000 Resilient Roofing Rebate ended in 2022.
- Short ownership. If you are selling within a couple of years, you may not recoup the cost through premium savings.
- Not hail-proof. Very large hail can still damage Class 4 shingles.
A simple way to run the numbers
- Get two quotes from us on the same roof: standard architectural and Class 4. Note the difference.
- Ask your broker for the annual discount, in dollars, for a Class 4 roof.
- Divide the upgrade cost by the annual discount to get a rough payback period.
- Then weigh what the numbers don’t capture: fewer claims, fewer leaks, and less disruption when the next storm hits.
For many Calgary homeowners, especially in the northeast and northwest where roofs have been replaced twice since 2020, the answer is yes.
Common myths about Class 4 shingles
“Class 4 means hail-proof.” It means the shingle survived a 2-inch steel ball in a lab. Larger or wind-driven hail can still damage it.
“My insurer will pay for the upgrade.” Usually not. Insurers replace like with like. The upgrade is your cost unless your old roof was already Class 4.
“Every Class 4 shingle is the same.” Products differ in weight, wind rating, warranty and how they age. Some use rubber-modified asphalt, others a reinforced backing.
“A Class 4 roof never needs inspecting after a storm.” It still does. Vents, flashing and gutters dent the same as before, and very large hail can still damage the shingles.
Questions to ask your installer
- What is the exact product, and can I see its UL 2218 Class 4 listing?
- Are the starter, hip and ridge products from the same system?
- What wind rating does the product carry, and will you use the high-wind nailing pattern?
- What does the manufacturer warranty cover for hail, if anything?
- Will you give me the documents my insurer needs for a discount?
Class 4 options beyond asphalt
Many steel roofing products also carry Class 4 ratings. Steel may dent cosmetically in large hail even when it does not leak, and some policies exclude cosmetic damage on metal roofs, so read your policy. See metal roofing for details.
Ready to compare? See Class 4 impact-resistant roofing or book a free inspection and we will bring samples and quote both options.