Is GAF Timberline HDZ a class 3 or 4 shingle?

GAF Timberline HDZ is neither a Class 3 nor a Class 4 impact-resistant shingle by default, it is a standard architectural shingle without a UL 2218 impact resistance rating for hail. GAF Timberline HDZ is tested for wind resistance up to 130 mph with Dura Grip adhesive and has good durability, but it does not carry a Class 3 or Class 4 impact rating, which is a specific rating for resistance to hail damage. The impact resistance classification comes from UL 2218 testing where steel balls are dropped on shingles to simulate hail. Class 1 is lowest, Class 4 is highest impact resistance. GAF Timberline HDZ is not rated under this test, so it is considered Class 0 or unrated for impact. If you want a GAF shingle that is Class 3 or Class 4, you need to look at GAF Timberline AS II, which is ArmorShield II, which is a Class 4 impact-resistant shingle designed for hail-prone areas and may qualify for insurance discounts. GAF Timberline AS II uses polymer-modified asphalt for better flexibility and impact resistance. Standard Timberline HDZ can still withstand moderate hail but will not have the insurance discount or impact rating. So if you live in a hail-prone region like Texas or Colorado, you should consider GAF Timberline AS II for Class 4 rating rather than standard HDZ.