Technical Specifications

FIRST CLASS PROTECTION

UL 2218

Underwriters Laboratories (UL) has one of the most

demanding standards for testing the impact resistance of

shingles. The UL 2218 test determines the amount of stress

a newly manufactured rooﬁng shingle can withstand without

cracking. It also rates the shingle’s performance. Duration FLEX

™

shingles have achieved the highest rating possible — Class 4.

Here’s how the testing works:

• Four different-sized steel balls are used to

simulate the force of free-falling hailstones

• To test impact resistance, shingles are struck

twice in the same spot

• A class rating is assigned to signify resistance

to a particular size steel ball — the higher the

class rating, the greater the resistance

Choose Duration FLEX

™

shingles along with ProEdge FLEX

™

Impact-Resistant Hip & Ridge shingles for a complete

UL 2218, Class 4 Impact-Resistant Roof System.

Class 1

Class 2

Class 3

Class 4

Class 1 1

⁄4" steel ball

Class 2 1

⁄2" steel ball

Class 3 1

⁄4" steel ball

Class 4 2" steel ball