How to Lay Felt on a Flat Roof

What You'll Need
30 pounds roof felt
Plywood planks (if old ones need to be replaced)
Roof felt adhesive (such as bitumen)
Galvanized nails

Felt is laid on a flat roof to help keep the roofing system waterproof. While laying felt is not an easy job, it can be done by anyone who has the patience to deal with it. Here are simple steps to get you started.

Step 1- Prep Work

Check to ensure the roof is in good enough condition to walk over. You will be looking for any decking that has rotted or bowed. These pieces should be replaced. If you need to replace any boards, be sure to coat them with a preservative. If you already have felt on the roof, remove it along with any excess nails. Roll the new felt out on the roof and allow it to stay on the roof for about 30 minutes. This will make it easier to work with.

Step 2- Placing the Felt

Using galvanised clout nails, nail down the first layer of felt. Ensure the felt remains even and straight as you work. It's best to start nailing in the center and work out from there. Paint a thin layer of adhesive over the first felt layer. You will be placing the second layer of felt over this. There needs to be an overlap in the felt to help increase the water tight quality. You wan walk over the roof to remove any air bubbles that may form.

Step 3- Finishing

A third layer of felt needs to be placed. Cover the edges of the roof with strips of felt before laying out the final layer. You will follow the same process as in step 2 for the last layer. Apply another layer of adhesive to the top for maximum waterproofing. You can cover the surface of the felt with gravel for added strength.