Working with fiberglass shingles is similar to working with asphalt shingles. In many cases, the shingles are a composite of asphalt and fiberglass material designed for durability and long life. When choosing a fiberglass only or fiberglass-asphalt composite for your roof, choose a material that has a certified minimum life of 25 years.
Step 1: Preparing the Roof
With the old roofing materials and debris are removed cleared away from the roof, you should have a clean surface to work on. Patch any holes in the roof and if necessary, replace worn or warped roof boards with lumber. Use the level to make sure there aren't any sags in the roof.
Step 2: Install Drip Edge
The drip edge should be installed around the edge of the roof and secured using roofing nails. The drip edge is an aluminum strip that should overlap at the corners. Any overhang material can be trimmed off using the tin snips.
Step 3: Install Ice and Water Shield and Underlay
Starting from the edge of the drip edge lay a row of adhesive back shielding. In many areas, the shield is a required installation. The material should come with an adhesive back to make it easy to use.
Lay the underlay next in rows overlapping a few inches. Staple in place with a tacker or stapler the underlay as it is unrolled, cutting any excess material off with the utility knife.
Step 4: Venting the Roof
There has to be away for hot air to escape the attic in order to prevent a build up of heat or any dangerous fumes that may be harmful or lethal to you. Cut holes in the sheathing at the top of the roof with a circular saw. When the vent holes have been cut, cover with the underlay and cut with the utility knife to reveal.
Step 5: Install the Fiberglass Shingles
Starter shingles, which look like the regular asphalt shingles without the tabs, should be laid at the drip edge, nailed down with roofing nails. Next, lay the fiberglass shingles, working from the lower corner of the roof upward, one row at a time. Fasten the shingles to the roof using the pneumatic nailer. The tar strip on the shingles is where the nails should be driven, roughly 3 to 4 nails per shingle.
Stagger the shingles so that the gaps do not directly line up from shingle row to row. Water would seep underneath and invade through the nail holes, causing the roof to leak.
Step 6: Install the Vent
At the top, place the roofing vent over the holes that were previously exposed and secure to the roof with roofing nails. Secure the roofing shingles designed for the vent over the top and fasten with nails. The loose corners of the vent shingles should be secured using roof tar or similar adhesive.