Impact Resistant Shingles

What are high impact resistant shingles? Typically, these are known as IR4 shingles. They're built to withstand hail damage more than the average shingle. The way they do this is they test them using a process called a class for UL 2218 impact test. Essentially, they're going to drop a metal ball about the size of a golf ball 20ft in the air under these shingles. Now a normal shingle is going to break under that. However, these IR4 shingles withstand it. And that's how they pass the test.