What function does shingle underlayment serve?
An underlayment, commonly known as roofing felt, will: • Protect the roof deck from moisture prior to shingle application; and, • Provide a degree of back-up protection in the event water gets under roofing shingles. Some local building codes and U.L. standards require that a shingle underlayment be installed. Ask your contractor if this is the case in your area. Also, some manufacturers offer a special underlayment product which prevents leaks caused by water back-up from ice dams–a common condition in many winter snow areas. Protection against ice dams can be obtained by using a waterproofing shingle underlayment at the eaves or lower edges of the roof, in addition to installing adequate ventilation and proper insulation in the attic floor. Ask your contractor about these specialized underlayments.
