You will better understand your roofing quote when you're familiar with the terminology. So, it pays to learn all the essential parts of a residential roof system before calling in the pros. Then, as an informed consumer, you'll understand what your roofer means when he explains the job scope to you – and that knowledge might mean money in your pocket.
This illustrated glossary looks at 16 essential parts of every roofing system and a few that are just good to know.
Quick roofing definitions
Wooden triangles spaced evenly across the span of the home to support the roof deck.
Plywood or OSB that covers the trusses and creates a platform for the roof covering.
A fabric covering that separates the wooden deck from the shingles to prevent moisture seepage.
Shingles, metal, or tile that covers the entire roof.
On a sloped roof, the horizontal line where two planes of the roof meet.
Openings that allow hot air to escape the attic space or that draw in cooler air from outside.
Metal strips at the roof's edge that channel the flow of water away from the fascia and roof structure.
Edge of the roof on the gable end.
The underside of the roof where it overhangs the sides of the home.
The covering that protects the eave of the roof.
The board along the long edge of the roof to which the gutters attach.
Metal strips that channel water away from areas prone to leaks.
The lowest point at which two roof planes meet that creates a channel for water runoff.
The uppermost point at which multiple sides of a roof meet in a hip-style roof.
The exterior wall of the house that fills in the end triangle created when two planes meet.
A window that juts out of a sloped roof.
Different parts of a roof explained
Your roof protects your home from wind, rain, and sun exposure – and it includes multiple parts that all perform a necessary job. Its durability, structural integrity, and lack of vulnerable areas are paramount in its performance.
It's important for a homeowner to become familiar with roofing terminology because it builds trust and establishes credibility. It's like taking your car to a mechanic and hoping you're not being taken advantage of because you have no idea what a tie rod end is. So, when a roofer says that they need to replace your chimney flashing, you know what that is and will understand the value of what they're providing.
Roof trusses
Roof trusses create the frame on which the entire roof system rests. They’re also what gives your roof the shape it needs. Simply put, roof trusses are triangles made of dimensional lumber spaced evenly across the span of the home.
The roof span (length) dictates what size of lumber is used–whether 2x4, 2x6, or 2x8. Trusses are manufactured in a factory and shipped to the job site. The builder orders the correct size, style, and number of trusses for the home's design.
In a timber-framed home built using interlocked heavy wood timbers, craftsmen frame the roof with individual rafters and joists instead of trusses.
Roof decking
Several layers of covering lie on top of the trusses or rafters. The roof decking (also called sheathing) is the bottom-most layer and creates a foundation for the other roof materials. It's made of plywood or OSB (oriented strand board), which measures ½" to ⅝" thick. The deck's thickness depends on the span of the roof and the material used.
When we re-deck a house, we use OSB. I'm not an engineer, but because the strands of wood are oriented in different directions, it feels stronger on homes with a 24-inch spacing between trusses.
Drip edge
A specially shaped metal flashing creates the drip edge at the roof's edge to channel water flow away from the fascia and into the gutters and downspouts. The International Residential Building Code (IRC) requires a drip edge to be installed on a roof to prevent water from flowing behind the gutters and damaging the fascia and roof deck.
Underlayment
The roof underlayment is a thin fabric covering the entire roof deck. It's placed under the roof covering (e.g., shingles) and is the first item included to prevent water infiltration and protect the roof deck from water damage and rot. There are two types of underlayment: felt and synthetic. Felt underlayment is made of paper saturated with asphalt and comes in several thicknesses. Synthetic underlayment is made of moisture-resistant, long-lasting polymers.
Flashing
Roof flashing consists of thin metal strips (often galvanized steel) that channel water away from areas vulnerable to leaks, like seams or joints, waterproofing the roof deck. You'll find flashing around a chimney or skylight, in the valley of a roof, at the roof edge, and around plumbing vent pipes.
Roof covering
On top of the underlayment is the roof covering. Composite or asphalt roof shingles are the most popular roofing material used as a covering. But in some regions of the country, you'll find other options used, depending on the style of homes and the weather conditions in different climates. Here are the most popular types of roof coverings.
Asphalt shingles
Slate shingles
Cedar shake shingles
Metal shingles
Clay tiles
Concrete tiles
Standing seam metal
Metal panels
Ridge and ridge capping
A roof's ridge is the highest peak where the sides of the roof meet. Depending on the shape and design of the structure, a home may have several ridges.
The ridge may include a few extra components. The ridge capping is a row of shingles that covers the ridgeline. If there is no ridge vent, they are folded over the raw edges of the shingles on either side to give the roof added protection and a finished look. If the roof has a ridge vent, the capping shingles cover it.
Ventilation
Extreme temperatures or moisture in the attic can increase energy costs, cause ice dams, and damage shingles. Adequate ventilation in the roof prevents this by moving warm or cold air out of the attic space, maintaining a positive airflow. Several types of roof vents move air in or out, and the ones you choose will depend on your taste and the roof style.
Exhaust vents allow attic air to escape. They include ridge, box, or turbine vents. On luxury homes, a cupola acts as an exhaust vent. Intake vents draw fresh air into the attic. They include gable, soffit, and over-fascia vents. For homes with little to no soffit, drip-edge vents double as a drip edge and a vent.
Soffit and fascia
Often mentioned together, the soffit and fascia make up the eaves of your home. The soffit covers the eave, and the fascia is the facing on the roof's edge, giving your home a finished look. The fascia also provides a place to attach the gutters.
Rakes and eaves
The soffit, fascia, rake, and eave give the edge of a roof a nice finish. The rake is the edge of the roof on the house's gable end. It's the same board referred to as fascia on the non-gable side of the house. The eave is the underside of the roof overhang along the walls.
Valleys and hips
Just as the ridge is the highest point where two planes of a roof meet at the top of the roof, the valley is the lowest point at which two planes meet. Roof valleys occur where the roof line changes direction, like in an L-shaped floor plan.
A pitched roof design with all sides sloped toward the walls is called a hip roof. The hip is the point where two flat planes meet, but not the highest point or the ridge. The hip end is the triangularly shaped flat plane on the roof.
Gable
A home with a gable roof includes two flat planes that meet at the ridge. The gable is the triangularly shaped exterior wall that fills in the peak made by the roof planes.
Dormer
Dormers are jut-outs in the plane of a sloped roof. Like skylights, they provide natural light. But they also add additional headroom to the interior. Dormers come in various styles, but on the outside, most appear to be small rooms with gable roofs. Many homeowners like that dormers provide additional living space in attics or low-ceilinged second floors.
Identify the part of the roof that needs repairs
Sure, knowing roofing terminology helps when speaking with a roofer. But, understanding how roof components are assembled, and perform to protect your home, empowers you to troubleshoot problems as they arise.
When you periodically inspect your roof (or pay someone to do it for you), you discover signs of wear before you have a major problem. You know it's time to contact a professional roofing contractor when you see things like curling shingles or algae growth. Also, an inspector will let you know whether you need a roof repair or a new roof installation.
To help you organize your roof care, download our comprehensive roof maintenance and cleaning checklist.
Frequently asked questions
The essential parts of a roof include the trusses, sheathing or deck, underlayment, covering (shingles or metal), flashing, and drip edge. Additional components include the soffit, fascia, rake, and vents. Depending on the style of a roof, different architectural components may be included, such as the ridge, valley, hip, gable, and dormer.
The trim on a roof's straight sides is called a fascia; on the gable end, it is called a rake.
A shed-style roof has the same parts or components as other roof styles. The difference is that the roof trusses will be shaped differently.
The national average cost to replace a roof ranges from $15,159 to $27,580, with most homeowners spending about $21,000. Of course, the cost depends on the style of the home, the height and slope of the roof, the roof type, the materials, and the geographic location.
While performing routine maintenance or a periodic inspection, if you notice missing or damaged shingles, sagging, or signs of water damage, then it's time to call a roofing professional for an opinion. They will let you know if you need a simple repair or a complete roof replacement.
Choosing between asphalt shingles, metal roofing, slate, wood, or tile is a big decision. Some roofing materials are better suited to certain roof styles than others. Other materials are best for historically accurate renovations. And then, you have a budget to consider. Discuss your ideas with your roofing company to get a professional opinion of the best high-quality materials for your home.
Carol J Alexander is a home remodeling industry expert for Fixr.com. For more than 15 years as a journalist and content marketer, her in-depth research, interviewing skills, and technical insight have ensured she provides the most accurate and current information on a given topic. Before joining the Fixr team, her personal clients included leaders in the building materials market like Behr Paint Company, CertainTeed, and Chicago Faucet, and national publications like This Old House and Real Homes.