The Different Layers of a Roof (And Why They’re Important)

Many homeowners look at a roof and only think about the shingles. That makes sense, right? Shingles are all you can really see from the street. However, a roofing system is much more complex. Each part of the system contributes to protecting your home from severe weather. Understanding the different layers of a roofing system is crucial to having a successful project and positive experience when hiring a roofing contractor.

Here are the layers of a roof, in order of application (bottom to top):

	Decking Most often made out of plywood, this roof layer is installed over the framing in a typical roof install. It provides structure by tying the trusses and joists together. You can usually see the underside of plywood decking from the attic.
	Ice/Water Barrier This self-adhering, water-proof, and self-sealing membrane is applied to the roof deck. It is designed to protect against water infiltration from ice buildup or wind-driven rain.
	Flashing This thin material is used to direct water away from where the chimney or siding elements and roof elements intersect. Flashing is usually made of metal, such as galvanized steel, aluminum, or copper. It tends to fail before the shingles do, and should be inspected regularly to make sure your home has a watertight seal.
	Starter strip These specialized shingles line every edge of your home’s roof. They are installed after roof decking and before underlayment. Their purpose is to seal the edge of your roof, significantly increasing the roof’s ability to withstand punishing winds and wind-driven rain.

	Underlayment This felt, or rubberized asphalt sheet, provides an extra layer of protection between your shingles and your roof deck. It helps reduce blow-off by allowing your shingles to lay flatter and more uniformly. Additionally, it prevents wind-driven rain from getting under your shingles and causing damage to your roof structure or the inside of your home.
	Shingles Shingles are the element that most homeowners are familiar with as it is the layer you can see from the outside of your home, and it is an important aesthetic aspect. Asphalt shingles come in two major types, 3-tab and architectural. 3-tabs are less expensive but also less durable, have lower wind resistance, and have a “flatter” appearance. Architectural shingles make up most roof replacements today, as their cost is only marginally more than 3-tab, and they come with far superior specifications and warranties.
	Ridge caps Typical shingles can’t cover ridges well, though, so this specialized extra-long shingle is installed along the ridgeline of a sloped roof. It fits over the joint between these two edges to keep rain and snow out of the home, while also allowing hot air to escape. Ridge caps also finish the look of the roof by creating a tightly sealed joint along the two sides.

We hope you gained a better understanding of the different layers of a roof. When it’s time for your next roofing project, schedule a consultation with one of our roofing experts.