There are three layers to roofing: the roof deck, underlayment, and shingles. Here’s what each layer does.
Roof decking commonly comes in plywood or composite wood, and it’s the first thing that is installed after your roof’s framing. It provides a solid flat surface to support your choice of underlayment and shingles.
Some homeowners might consider underlayment optional, but it is an important layer that prevents mold, water damage, and leaks. After it’s installed, you won’t have to worry about how it looks because the shingles will completely cover it. You can choose a variety of materials as underlayments based on durability, weather protection, and pricing.
Shingles come in a variety of materials, each with its own appearance, durability, and cost. Shingles are typically rectangularly shaped and installed in overlapping layers on top of your underlayment. They are first installed from the bottom layer and successively work their way up the roof.