For those who are not familiar with roofing terminology, roofing underlayment is a waterproof material that must be installed directly onto the roof`s deck, under the other roofing materials. It is an additional protection layer, which will turn to be very efficient in the case of severe weather, when shingles or tiles alone will not handle the situation
Roofing underlayment can be made of different materials: asphalt-saturated felt, rubberized asphalt or non-bitumen synthetic underlayment.
Shingles and tiles are the first line of defense; they block precipitations, withstand wind and reflect the solar radiation, but they are not completely sealed and infallible. Sometimes, they can become vulnerable to wind-driven rain, not to mention that they can become brittle from age or improper roof installation and/ or maintenance.
Water-resistant roofing underlayment provides the additional necessary protection. It is not always necessary, but according to seasoned San Jose roofing contractors, the benefits it provides should be enough to be taken into consideration. It increases the protection provided by a roof especially in case of low-sloped roofs; it also improves the fire resistance of a building.
The roof underlayment is typically applied in long, overlapping strips, able to protect the joints and seams and also to form a seal around nails, preventing leaks.