Shingle Roof Underlays

The first component to be installed on the roof is underlayment. Underlayment’s are manufactured and designed with different properties for the home, climate, and roof covering materials needs.

One of the main functions of underlayment is to act as a moisture barrier.   Most roof covering materials are not waterproof, but water-resistant, and are designed to be installed over a waterproof or water-resistant underlay, or in conjunction with the underlay.   Some underlay’s are designed with superior strength to act as a secondary protection should there be damage to the roof i.e. wind blow off while others help to achieve a class A fire Rating for the product being installed.

For a Fiber Glass Asphalt Shingle Roof System, the underlay is installed under the roof system and over the roof deck assembly.  This underlay is an integral component as it provides protection against moisture migration for a fiberglass core roof system.  Felt Paper is an example of a common underlay used in this system. It is water resistant and breathable, and will offer good protection against moisture migration on your home.

Roofing underlay is also useful in protect the roof structure below by providing a second line of defense against water entry and protecting the roof deck from condensation that forms on the underside of the roofing material. Protecting the roof sheeting and the structure from moisture is important in maintaining the integrity of the building, in particular the roof sheeting.  A good example of a water resistant, superior strength, breathable second line of defense underlay would be Gaff Deck Armor.   Most asphalt shingle require an underlay and I would recommend choosing a breathable underlay like Felt Paper or Gaff Deck Armor for the second line of defense on your home.

Reece Jorgensen