Roofing experts agree that installing shingle roof deck underlayment is essential to a leak proof and long lasting roof system. Why install shingle roof protection? Here’s why. Roof deck protection serves as a secondary water shedding protection in case of roofing leaks. Shingle protection, roof deck underlayment keeps wood resins away from the shingles. Some resins can damage the shingles, so be mindful of what touches the shingles. Deck leveler, shingle roof protection helps to create a flat and an even deck surface. Breathable layer which helps prevent inside moisture from becoming trapped within the roofing system itself. Finally, roof deck protection is needed to obtain a UL class A fire rating on shingles. The reason you need breathable underlayment protection on the roof which goes under the shingles is to make sure your roof breathes to reduce excess moisture and assure maximum protection against hard rains and heavy winds.
Today’s modern houses are built weather-tight, so common moisture form cooking, bathing, cleaning, etc. has less of a chance to escape. Using non-breathable roof protection on the deck can create a barrier that traps harmful moisture inside your roofing system. Over a period of time, this can cause roof rot, mold, mildew, and very costly structural decay. Many homeowners do not know that moisture can travel turning into vapor, the moisture can travel through the ceilings, once airborne, and it will migrate through the ceilings using natural convection. Moisture stops at first waterproof barrier, in this case, the non-breathable roof deck protection. The moisture condenses between the roofing and deck, changes from vapor to water, and then can settle between the deck and the non-breathable roof deck underlayment.
When there is trapped moisture, your roof protection does not breathe, it may trap moisture between the top of the roof deck and the underside of the roof protection. The risks of trapped moisture can be that the plywood can delaminate and rot, OSB can expand and also rot, structural frames can warp and rot, shingle blow-off can happen, roofing nails can rust and lose their ability to hold the shingles in the correct place. There are some synthetic roofing deck protection that does not breathe. Their very makeup does not allow the moisture to pass through them. Manufactured from plastic/polymers, these products are not the asphalt roll roofing that many individuals may think of when they hear the term roof deck protection.
The reasons to use a roof deck underlayment are because of fewer buckles on the roof due to its fiberglass construction. It can straighten itself with sunlight, if it does not wrinkle. Acts like a breather so attic moisture can breathe through it.