Class 4 Impact-Resistant Shingles: What the Rating Means
Roofer Finder points to one reference in depth: Class 4 Impact-Resistant Shingles: What the Rating Means on the National Roofing Directory. Below is what it covers and where to read it in full.
Read Class 4 Impact-Resistant Shingles: What the Rating Means →The Class 4 rating in brief
Impact resistance for roofing is commonly rated under UL 2218, which drops steel balls of increasing size onto the product. Class 4, the highest class, means the sample withstood the 2-inch ball without cracking.
- Class 4 is the top rating in the UL 2218 impact test.
- Some insurers offer premium discounts for Class 4 roofs, so ask yours.
- Impact-resistant shingles cost more than standard shingles.
What this reference covers
These are the sections of Class 4 Impact-Resistant Shingles: What the Rating Means on the National Roofing Directory.
- What the rating actually measures
- What it does not measure — the part everybody skips
- Two engineering routes to Class 4 — and they are not the same product
- The insurance side, in the order it actually happens
- The upcharge, and doing the arithmetic honestly
- Why a Class 4 roof still gets replaced
- Where the rule breaks down
- Keep Reading
- Need a Contractor Who Knows This Detail?
From the reference
Class 4 is the top step of a four-step scale, and the whole scale comes out of one laboratory procedure: a steel ball dropped onto a shingle, twice in the same spot, and a technician looking for a crack — including on the back of the sample. That is the entire measurement. It is a real number about one property of one new shingle, and it gets sold as though it meant the roof cannot be hailed.
Roofers want to know which of the two very different ways of building a Class 4 shingle is in the bundle, because they do not behave the same on a cold roof. Homeowners want to know whether the insurance credit pays for the upcharge. Both answers are here, in that order.
Excerpted from Class 4 Impact-Resistant Shingles: What the Rating Means on the National Roofing Directory. Read the full reference for the complete treatment.