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We all know what a roof looks like, but how well do you really know your roof? At first glance, your roof is simply a covering made from shingles, tile, metal, or slate, but dig deeper and you’ll find your roofing system is made up of so much more than its visible exterior.

Residential Roof Diagram

Residential Roof Diagram – Image courtesy of the National Roofing Contractors Association.

Parts of a Roof

Getting to know the parts of a roofing system is easy if you think of a roof in terms of layers. The National Roofing Contractors Association (NRCA), which like the Roofing Annex is dedicated to educating consumers so they can make smart roof buying choices, breaks down a roof system into five main elements.

The major parts of a residential roof
Roof structure
This is the framework of the roof, or the first layer. It consists of rafters and trusses, which are beams that form the shape of the roof and support the sheathing or the next layer. Drainage features are also established during the roof structure phase. These features, like the roof’s shape, layout and slope, are important because they allow water to roll off the roof.
Deck or Sheathing
These are roofing panels, typically made from plywood, wood plank, or waferboard, that cover the roof structure.
Used to protect the decking or sheathing from water, moisture and debris, the underlayment is made of roofing felt paper or synthetic materials. The type of underlayment used is based on environmental factors, such as the weather conditions the roof will be subjected to and the location of the home or building. The underlayment is also referred to as tar paper because of its appearance.
Roof Covering
This is the final layer on the roof and covers the sheathing and underlayment. It can be whatever roofing style you choose, such as asphalt shingles, cedar shakes or shingles, slate, tile, metal, or synthetic roofing materials. The roof covering is what gives your roof its stylish appearance.
Typically sheet metal or some other durable material, the flashing tucks in the roof covering around chimneys, vent pipes, joints and intersecting angles or valleys that occur with certain roof structures. Flashing prevents water seepage and leaks by directing water away from the roof’s interior and down gutters and downspouts.

Other Roofing Terminology to Know

Depending on the style of your roof, other roofing terms may apply. Among the most common ones are:

This is the part of the roof that hangs over the edges or side walls of the structure. A cornice finish can be made from metal or wood.
An addition that extends up and out of the roof. A dormer could contain a window, create a balcony, or provide extra space in the roof to accommodate head room in an attic.
Drip Edge
A piece of metal, plastic, or vinyl that runs along the edge of a roof to help water drip off the roof covering. The drip edge is invisible from the ground because it is installed under the final layer of shingles.
Created by hanging the roof covering material over the edge of a house or other type of building.
Provides a finished look to a roof. The trim board, which can be wood or metal, is placed around the roof’s perimeter. Fascia is also used to mount gutters to the roof and is installed behind eaves to finish off or cover their ends.
The seam that forms when the sides and the top of the roof meet.
A finishing underside for eaves or parts of the roof that extend beyond the structure’s exterior walls. Soffit vents are often built into this piece to provide ventilation.
Starter Strip
Made of shingles or an ice-proof membrane, it is layered on top of the underlying roofing components to protect against wind and other weather conditions.
The dip that forms when two sections of roofing come together at a downward angle.

Turn Your Roofing Knowledge into Buying Power

Whether building a new home or replacing the roof of an existing home or building, knowing what you’re paying for is essential in obtaining a quality roofing system at the best price. A knowledgeable consumer is also able to better convey their roofing preferences, recognize roofing issues, such as leaks or roof storm damage, and ask key questions regarding the performance of their roof.

When you contact the Roofing Annex about roof work, we provide a roofing estimate or a roof assessment, depending on the situation. This information outlines what services you will be receiving from us. We take the time to explain everything to you and try to take as much technical roofing jargon out of our explanations as possible. The way we look at it, a new roof is a major investment, so we want to invest the time in you so you can be confident that you are getting the best roof for your money.

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