If underlayment is not used on a roofing application, is the shingle warranty voided?
No. It’s a recommendation, not a requirement. Standard shingle underlayment is not warranted by the manufacturer against defects in manufacturing. Some manufacturers make their shingle warranties conditional upon use of underlayment The use of WinterGuard or a double layer of standard shingle underlayment is required on slopes of 2/12, up to 4/12. However, we strongly recommend the use of underlayment on all slopes to “dry in” an exposed wood deck and to comply with Underwriters Laboratories requirements. Waterproofing shingle underlayments, do not, in many cases, carry a warranty. Some carry warranties for five years. WinterGuard is warranted to protect against leakage, wherever it is applied, for 10 years.
