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19 Parts of a Roof

A roof system is one of many complex systems that make up a home. Read on to learn the terminology and the roof components you need to know before making important decisions regarding a residential roof.

Created image of a white home with orange roof with labels for all the different parts

If you recently received the news that you need a new roof, you’re about to undergo a complex and costly procedure. Making an informed decision about your roofing system will help you be confident when it comes time to make an expensive investment for your home.

A roof system is one of many complex systems that make up a home. It includes all the elements and materials that make up the roof structure. The roof design and shape will also determine the type of roof needed and the materials used.

Before you call your local roofing contractors, study our guide on the parts of a roof. We will get you acquainted with the terminology and the roof components you need to know before making important decisions regarding a residential roof.

Parts of a Roof and Their Functions.

The shape and design of the roof dictate many of the parts and characteristics a roof will have. The roof diagram above shows the most common roof features that you will need to know when becoming familiar with the roofing system. Understanding your roof will make your roofing projects easier and help you make the most of your budget.

1. Roof Valleys

Close up oof a brick home with dark brown tile shingle roof with a skylight, blue sky with white clouds above

A roof valley is produced when two roof slopes meet, and this line is called the roof’s valley line. This “V” shaped line of the roof valley is one of the essential parts of a roof because it allows excess rainwater or melted snow to flow down into the gutters. Valley flashing is an underlayment that provides a waterproofing seal on the valley line and directs the water off the roof.

2. Roof Ridge

Birdseye view of a gray shingled rooftop showing the ridges, green lawn in backyard and a kids play structure, sunny day

A roof ridge is where two slopes or roof planes meet together in a peak and forms the highest part of the roof. This line, where the two roof planes meet, is known as the ridge board. A ridge board is the piece of metal resting on the roof’s peak and creates the roof’s triangle shape. A ridge can run horizontally across the whole roof, or there may be multiple styles depending on home design.

The ridge vents are one of the most popular vents installed on the roof. Ridge vents are vents that are cut out and run the entire length of the ridge. This type of vent is the most popular because it is not noticeable from the ground.

3. Skylight

Brwon rooftop with 3 skylights, blue sky with some white clouds and trees above

A skylight is a window that is cut directly into the roof. Skylights are a luxury feature because they are expensive and can be complicated to install. First, the roof components are removed, and high-quality waterproofing material, like skylight flashing, is installed to prevent leaks.

Skylights provide natural light by allowing the sunlight to stream in from the top of the house. They are perfect to use when extra natural light is needed, like in an attic space.

4. Drip Edge

Man in red baseball cap and shirt with blue jean on top of roof using a yellow leasuring tape

The drip edge of the roof is a type of angled metal flashing installed on the roof’s perimeter edge. The drip edge helps move the water away from the fascia and protects all the roofing components from being subjected to damage caused by standing water.

 Building codes almost always require drip edges on homes in the United States to meet the current roof code.

5. Roof Hip

Two story home, comination of gray and white stone with some brown colored stucco, arched doorways and large light fixtures on columns on either side of doorway, large green front lawn with green bushes and red flowers, tall green trees and blue sky above with sun shining

A roof hip is the outward diagonal where two slopes meet. A hipped roof is a type of roof where all sides gently slope down towards the walls. A hipped roof is often used in snowy or windy climates because the snow and ice easily slide off the slanted sides.

6. Hipped Edge

The hip ridge is the external angle where the vertical, diagonal sides of the roof meet.

7. Rain Gutter

Man wearing a blue shirt and ball cap and red and white work gloves on a ladder cleaning out leaves and debris from the rain gutter, sun peaking through tall green trees in background

A rain gutter is part of the roof system that helps remove water and keeps it from collecting on the roof, where it can cause damage. A rain gutter is a narrow channel similar to a trough hanging below the roof’s eaves. Water collects in the track and moves down the chute, where it is released at ground level.

A valley roof is a typical roof style that depends on gutters. It has two pitched roofs that form a right angle. It is common for this part of the roof to accumulate water and debris, and the gutters are vital to keeping the roof dry and healthy.

8. Downspout

Blue sky above a cream house with black trim, black windows and a black downspout

A downspout is a vertical pipe that attaches to the gutter and runs down the side of the home. Rainwater travels through the downspout to be released at ground level. At the end of the downspout is a splash block, which directs the water away from the house’s foundation.

9. Flat Roof

Blue sky with white clouds, Spanish style home, all white with black window trim and doors, Spanish style shingled roof, simple flat roof lines

A flat roof is a roof that is almost entirely level. Even though this flat and rectangular roof appears flat, it has a slight slope of less than 10″ to allow water to run off.

10. Flashing

Man on roof wearing a blue shirt and pants and a white hard hat working on installing metal flashing to the base of a brick chimney

Flashing is a thin piece of metal roofers use to direct water away from the roof. It is placed in critical areas where vertical and horizontal planes meet and are a potential area for water damage.

Roof flashing is used in specific areas of the roof that require more protection, like where a vertical structure meets the roof. Vent pipe flashing along with dormer windows, chimneys, and skylights are roof features requiring flashing.

There are many types of flashing used for specific applications on the house roof. Flashing is a type of roofing material made of thin galvanized steel, aluminum, or plastic. It prevents water from flowing near roof openings and seeping into the roof.

11. Dormer

White building with a red roof and 6 dormer windows, light blue sky

A dormer window is a vertical architectural structure that contains a window and projects from a sloped roof. A dormer requires dormer flashing, a material made specifically for this type of structure that keeps out all water and moisture.

12. Abutment

Close up of a brown shingled rooftop, hunter green home with white trim, light sky and tree tops in the background

The abutment is a term used in roofing and bridge construction. In roofing, it simply means the joint where the roof attaches to the wall or any structure above it.

13. Soffit

Close up of the soffit on the underside of the eaves on a home, white home with black shutters

The soffit is the underside of the eaves, the part that hangs over the house wall. The soffit is made of any finishing material, like wood or fiber cement. It covers the underside of the roof’s overhang to conceal the ceiling joists and rafters. It is essential because it is used for ventilation and can help move hot air out of the attic. Attic ventilation is important to reduce humidity levels and prevent mildew and mold.

14. Sidewall

Blue sky, black building with lots of white trimmed windows

A sidewall is where the wall and the sloping section of a roof meet to form a junction. The primary function of the sidewall trim is to prevent water from running down the outer wall and seeping into the roof.

15. Eave

Close up of a Spanish style home with orange ceramic tile roof and large chimney, brown rain gutter attatched to the overhanging eave

Often a roof will overhang the walls of the home. This overhang follows the slope of the roof and is called the eaves. The eave of a roof is the lowest point of the roof. It is the point farthest from the ridge on a pitched edge. The roof edge is where the water drops off the roof into the gutters.

16. Fascia Board

Close up of a roof pitch, white trim with a Fascia boards creating a decoratice peice appealing to the eye, blue sky above

The Fascia board is attached where the roof meets the house’s walls. It is a wooden board attached to the rafters at the eaves. The ends of the lower roof covering material usually rest upon the fascia.

17. Gable End

Close up of the pitched roof on a red brick home, upper window with black shutters, bue sky with white clouds above

The end of a pitched roof between the borders of the crossing pitches is referred to as a gable. A gabled roof is typically triangular and reaches up to the ridge. A gable roof is often considered the “storybook” roof. The gable end refers to the gable roof and the wall that extends below it. Gable end vents are a particular type of vent for the Gable roof that help keep the attic space ventilated.

18. Gable Rake

Gray and white home with a black shingle roof and gable rake trim, blue sky

The gable rake is a type of trim on the gable. It is a piece of metal finishing flashing placed along the sloped edge of the dormer or gable. Rake trim can have an overhang like an eave or be flat with no overhang.

19. Chimney Flashing

Close up of the base of a red brick chimney showing the metal flashing

Chimney flashing is flashing used around the chimney creates a waterproof seal to protect the chimney and roof water damage. If the sides of the chimney aren’t careful sealed during roof installation, water damage can cause the entire chimney to be replaced.

More Roofing Terminology You Need to Know

Ceiling Joists

Image of an all wood ceiling showing beams and joists, sun reflecting off

Joists in the ceiling are horizontal beams that run from one wall to another in a parallel direction. Beams are fastened to the top of the wall at the wall plate to support the structure. In certain buildings, the joists that support the ceiling on the top level of a structure are also used to support the flat roof.

Plumbing Vents

Close up of a damaged plumbing vent on the top of a roof with black shingles

The plumbing vent helps to regulate air pressure in the plumbing system. It releases gas, air, and odors from the home to the outside through small pipes that exit the roof.

Mansard Roof

Close up of the top of a mansard style roof with white trimmed bay windows, yellow siding with white trim below, solid blue sky

A Mansard roof is a four-sided roof with two slopes on each side. This roof style provides more room in the attic and is a simple way to offer the maximum amount of living space in a home.

Roof Insulation

Interior of an insulated ceiling before being covered up, 2 sky lights letting sunlight through

Roof insulation is just as important as the other insulation in the home. If the roof has poor insulation, heat will rise straight out of the room, and the house will be cold all winter.

Pitched Roof

Cloe up of two roof pitches with a gray roof top, blue sky with some white clouds

This roof is the opposite of a flat roof which has a minimal slope. A pitched roof slopes downward from the central ridge. There are several types of pitched roofs that vary in steepness. One standard pitched roof design is the typical Gable roof.

Roof Deck

Man in white hard hat on top of roof installing wood decking

The roof deck is the structural foundation for the roof. It is often made of wood or plywood and is covered with an underlayment before the shingles are installed.

What Are the 3 Main Components of a Roof?

Many parts of a roof work together to cover the house and protect it from the weather and elements. A roof deck, underlayment, and roof shingles are the main focus of roof design. A roofing contractor will determine which parts of a roof you need and help you make the best selection of roofing material.

Roof Decking/Roof Sheathing

Large building with men on top of roof laying wood decking, then underlayment layer followed by gray colored shingles, sunny day

Roof decking and roof sheathing are interchangeable words that refer to the roofing material that make up the roof’s framing. The type of deck will significantly influence the rest of the roofing materials chosen for the structure.

A deck is the foundation of the roof. It covers the entire top of the roof framing and is the base for how the rest of the roof system materials are attached and installed. Commercial buildings often have steel or concrete decks, while a residential home almost always utilizes solid decking.

Plywood or wood planks can also be used as the roof deck, but solid decking is sturdier and can hold more weight. Composite decking, is made of solid materials that resemble wood. It is made of flat boards that attach to the trusses and are laid across the roof joists.

Men on old building renovating roof, laying underlayment over wood decking, sunny day

The downside to using wood as the roof decking is that it will eventually wear out or become rotten in spots. The shingles covering the roof decking do a great job protecting it from the elements. However, they can become loose or damaged over time, allowing water to seep onto the roof sheathing and cause damage.

Unfortunately, damage to the roof decking is hidden under the shingles and underlayment and cannot be seen until the whole roof is torn off. If the roof decking needs to be replaced or repaired, it will take dismantling the entire roof to determine what part of the roof decking is damaged and what is salvageable.

Roof Underlayment

 3 Men on a roof installing layers of underlayment

After the roof decking is in place, an underlayment layer is installed. A roof underlay is a woven barrier traditionally manufactured using asphalt felt. Newer roof underlayments are synthetic materials.

The underlayment layer is placed directly onto the surface of the solid decking board before the roof shingles are attached. The underlayment usually is made of waterproofing material like rubber strips or sheets of synthetic material. Once the roof is complete, the underlayment will not be visible.

Men on a roof installing layers of underlayment before installing ceramic tile shingles

The function of the underlayment is to protect the rafters with a water-resistant layer that moisture cannot infiltrate. This waterproofing layer helps prevent moisture and water from trickling down into the seams when installing the decking. The roof underlayment also protects the shingles from any resin from the wood decking as it ages.

Synthetic Underlayment

Close up of synthetic underlayment on a roof

Roofing contractors most often recommend synthetic barriers because they are superior in preventing moisture and weather damage. It is also lighter and can be used across the entire roof deck. It is also one of the more expensive choices, but if your budget doesn’t allow for this product, other, more budget-friendly choices might not last as long but will still add protection to the roof.

Felt Underlayment

Clsoe up of a man wearing yellow and gray work gloves using a hammer to install a felts underlayment on a roof

A more budget-friendly choice is asphalt-saturated felt, which is water-resistant but might not withstand the harshest weather conditions. Asphalt saturated felt also referred to as felt paper or tar paper. It is less expensive than the newer synthetic underlayments like rubberized asphalt and comes in different thicknesses, enabling it to be used in various applications.

Ice and Water Protector

Close up of the roof orick hme, snow on roof and icicles hanging from eaves, sunny day

This special underlayment prevents ice dams, which occur when ice builds up on the roof’s edge. This icy buildup can form a “damn” that prevents water from exiting the roof. A buildup of water on the roof can drive water and moisture between the shingles and cause significant damage to the roof.

Ice and water protectors are installed on the roof eaves and the roof valleys where water can pond. It is also used on surfaces of low slopes, flat roofs, and protrusions, like the chimney, roof vents, and skylights.


View of the top of a roof of a home, gray shingles

Shingles are roofing materials made of composite materials in flat and rectangular shapes. They overlap to form a watertight and wind-resistant seal, which helps preserve the roof from damage caused by the climate. Asphalt, metal, wood, clay, and slate are the other materials that may be used to make shingles. Your property will be just as well protected by these varieties, though some may perform better in certain climates.

Starter Shingles

Man on roof in reflective vest using a nail gun to install starter shingles on a roof

Starter shingles are a row of material underneath the first row of installed shingles. Starter shingles are cut to look like they are three separate shingles but are just one piece. Using starter shingles ensures there is roofing material between all of the joints where the shingles line up against each other and along the roof’s edges.

Asphalt Shingles

Close up of a roof with gray aspahlt shingles, green trees and blue sky behind

Asphalt shingles are the most popular and are designed to copy the look of tiles, wood shake, and other expensive roofing materials.

Architectural asphalt shingles, or laminated shingles, are becoming more common, particularly for high-end residential construction. Architectural shingles help to create a three-dimensional appearance for the roof. In addition, there is a greater selection of colors and designs available for architectural shingles, which contributes to an increase in the aesthetic value of a house.