While a new residential roof can be both exciting (and perhaps a bit intimidating) the roofing industry has a language all its own.

Many people will find themselves in a world of unfamiliar terminology when it comes time to speak with a contractor in person about your roof repair or replacement.

We’ve broken down the parts of a roof from the bottom up so you better understand what your roofing contractor is talking about.

This diagram shows each part of the roof discussed below. 1. Ceiling Joists

Ceiling joists are installed above the wall framing and are responsible for holding up the ceiling in your home. Without ceiling joists, the walls would simply crumble from the pressure of the roof.

The ceiling joists are the part responsible for holding your home's ceiling. 2. Rafters & Trusses

Rafters and trusses are both used for roof framing.

If your home has been built in the last 30 years, it was probably built with trusses. These parts are more commonly used because they are more economical to build off-site and deliver to the construction site in packages.

Rafters are cut and built on-site and used only for more custom or traditional builds.

Rafters and Trusses are parts of a roof that are used for framing. 3. Rafter Ties

Rafter ties are installed at the bottom third of the roof structure. They are essential to support the rafters and keep the walls below from spreading under the weight of the roof. Without rafter ties, the roof would pancake and push out the sidewalls. Rafter ties are usually required by code.

Rafter ties are the parts of a roof required to help spread out the weight.4. Ridge

The ridge or peak of the roof is the area where two roof planes meet and are the highest point on a roof.

The ridge is the part where the two planes meet. 5. Collar Ties

Collar ties are installed in the top third of the roof structure and are used to prevent separation of the roof at the ridge due to wind uplift.

They are often needed, but not required. Many homeowners end up removing collar ties to increase attic space. Whether or not this is possible requires the approval of a structural engineer.

6. Roof Decking / Sheathing

This is the foundation of your roof. It is the base layer of wood that sits on top of the structural trusses. It covers the rafters and supports the weight of your roofing materials.

Often also referred to as sheathing, roof decking is typically made from plywood or particle board and is a critical component to the structure of your home.

The decking/sheathing is the part of a roof that serves as the foundation. 7. Underlayment

The underlayment is a waterproof or water-resistant material placed directly on a roof deck. The main job of underlayment is to keep your home waterproof.

The underlayment is an important part of a roof that helps prevent water damage8. Insulation

This is a critical component of the attic to prevent heat loss. Attic insulation is designed to reduce the overall heat transfer to decrease the energy demands of HVAC systems.

Insulation helps your HVAC system run smoothly by keeping cold and heat in. 9. Ventilation

Roof ventilation keeps your home’s atmosphere comfortable and prevents moisture damage. This should be a system of intake and exhaust vents to provide adequate air circulation.

Ventilation keeps your home comfortable and prevents moisture damage. 10. Battens

These provide the fixing point for roofing materials as an alternative to attaching materials directly to the roof deck. Roof battens are preferred by many builders and have been used for years. There are some situations where a roof batten system must be used, like in cases where the HVAC system is on the roof, or for slate tiles.

Battens are parts that serve as an alternative to attaching materials directly to the roof deck. 11. Valley

A roof valley is where two slopes meet and form a V angle. These are used to improve water runoff and support drainage.

Valley shapes are lightweight roofing structures that provide a beautiful, classical appearance.

The valley is the part where the two slopes meet and form a V angle. 12. Eaves

An eave is the part of the roof that overhangs the exterior siding. Eaves can be both decorative and practical. While they are an element of classic architecture, they also protect the siding and foundation of the structure and a sunshade for interior spaces.

The eave is the part of a roof that protects the siding and foundation. 13. Soffits

This is the underside of the eaves, where the fascia and gutters are connected to the wall. The soffit serves several purposes.

It is a source of ventilation and can prevent pests from getting into the attic.

Soffits serve as a source of ventilation and can keep pests out of the attic. 14. Fascia Board

The fascia is the vertical facing board that supports the bottom row of roofing materials. It is typically PVC material and is designed to keep moisture from entering the roof.

The fascia board is typically made from PVC and is designed to keep out moisture. 15. Gutter & Downspout

The gutter and downspout are the drainage system of your property.

This system is critical for handling rain and snow and directing the water off of your roof and away from your home.

The gutter & downspout serve as the drainage system of the home. 16. Roof Covering

This is the outermost layer of a roof. The most popular materials are asphalt shingles and metal. Any type of roofing material should act as a waterproof barrier to protect the whole building structure.

The roof covering is the outermost layer of the roof. 17. Chimney

Any type of heat source in your home requires a chimney to disperse byproduct gasses, like carbon dioxide. Any type of fireplace including wood, coal, gas, or oil requires a chimney to remove hot gasses.

The chimney disperses any gasses from heat sources in your home. 18. Skylight

A skylight is basically a flat window on your roof. These are often added for a variety of reasons. They can increase light, and ventilation, while providing an architectural and stylistic statement.

A skylight can increase light and ventilation, while also improving curb appeal. 19. Dormer

A dormer is a vertical projection that typically holds a window. They are different from skylights because they are typically gabled or hipped rather than flat on the roof’s surface.

A dormer is a vertical projection that usually holds a window. 20. Flashing

This is a thin metal material installed around any curved areas on the roof to add extra protection.

Flashing is always installed around vents, chimneys, skylights, and dormers as these areas are more vulnerable to storm damage.

Flashing is a thin metal material around any curved areas to improve protection.

Understanding Your Roof’s Anatomy

Your roof is a complex but critical part of your home.

All of these parts of a roof play an integral role in either the structural, functional, or aesthetics of your roofing structure.

If you have any questions about your home’s roof or gutters, give Prime Seamless a call today!