What Are the Parts of a Roof?

Ben Kissam
Written by Ben Kissam
Updated June 9, 2021
Garage view of home with shingle roof
PC Photography/iStock/Getty Images Plus/Getty Images

Knowing all the parts of a roof can help you save money, diagnose heating and cooling issues, and protect your home from water damage

Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.

Knowing your roof’s components helps you better understand repair costs (and avoid roofing scams), plus diagnose or be on the lookout for heating, cooling, water, and plumbing problems.

With an understanding of roof structure, you’ll also be better equipped to determine if your roofing project requires a roofing pro near you or if you can do it yourself. Let’s get started!

1. Chimney

The anatomy of your chimney is interesting. A chimney is a vertical pipe that runs through the roof of your home, and is typically made of brick. The chimney transports smoke and other gasses (and maybe even Santa Claus) from your fireplace out of your home.

2. Rafters

Think of the rafters like the skeletal system of your roof. Rafters are designed as a sloped structural unit using mainly 2x10s or 2x12s and extend from your home’s ridge to the wall plate.

Rafters give your home its shape. They also often play a role in which type of shingles you might select (see #4 for more) when building or restoring a roof.

3. Trusses

Some roofs use trusses instead of rafters. The main differences are that trusses use shorter pieces of wood (usually 2x4s) and are often prefabricated and installed all at once.

Because trusses require fewer materials, they are often more affordable than rafters but just as strong, which is why many newer American homes use them.

4. Covering

Your roof’s covering is the part that’s most visual from the outside. It’s also primarily responsible for protecting your home from weather damage.

Today, roof coverings consist of a variety of materials, including:

More environmentally friendly options, such as solar tiles and green roofs, are also becoming common. Solar tiles generate electricity for your home, while green roofs are made using recycled and repurposed rubber and other materials.

5. Flashing

Often made from galvanized steel, roof flashing is one of the roof layers professionals install to direct water away from important or vulnerable parts of your roof.

When inspecting your roof, look for vertical points, such as areas along the chimney or plumbing vent. These locations are prime candidates for flashing installation, as the sharp angles make it easier for water to get through.

6. Sheathing

The sheathing is the layer of flat wooden boards that attach to your home’s rafters or trusses. 

The most common materials used for sheathing are plywood and oriented strand board (OSB). Roofers use a nail gun to secure individual panels down, making your roof into one cohesive unit.

7. Underlayment

Sandwiched between your home’s shingles and sheathing, underlayment is not always included on standard roofs. But when it is, it provides an extra layer of security from water.

Professionals often install underlayment on roofs with low slopes due to slower water runoff. Vulnerable areas of the roof might also get this extra layer of protection.

8. Ridge

The ridge is your home’s highest point, where the two sloping roof components meet. It’s found on various styles of roofing, including gable roofs, which are the most common.

A roof’s ridge is critical for two reasons. First, it provides vital stability for your roof structure. The ridge acts like a spine that holds the two sloping pieces together. 

Second, most ridges contain a ridge vent, an air exhaust vent on top of your home that helps your home stay cool.

Since hot air rises, many home builders recommend this a ridge vent over a roof vent. Giving your home a vent at the furthest possible point prevents pockets of warm air from getting stuck in your attic.

9. Drip Edge

The drip edge is a molding that seals the edge of your roof by the eaves and prevents water damage or moisture from getting inside. 

It attaches right at the point where the edge of your roof meets the siding of your home.

10. Fascia

Roof fascia is a series of wooden boards that give structure to the side of your house. 

Without fascia, your gutters and downspouts wouldn’t have as much support and would merely hang off the side of your home.

11. Gutters

Gutter systems guide rainwater off your roof and direct it away from your home.

Gutters prevent water from pooling on your roof and channel water away from the area right next to your home, so rainwater doesn’t seep into your home’s foundation.

12. Downspouts

Downspouts carry water down the side of your home from the gutters. 

Some homes have long pipes fitted at the bottom of their downspouts that direct rainwater into the yard. Others install underground downspouts, which guide rainwater to the street, driveway, sidewalk, or a section of your yard further from the home.

13. Soffits

Soffits work to keep your home dry and are equal parts functional and aesthetic. They hang off the side of your roof (underneath the fascia) and provide extra protection from the elements for your rafters.

14. Skylight

Skylights allow natural sunlight to flow into your home. The benefits of installing skylights on your roof include better ventilation, more natural sunlight, and more natural views.

There are some potential downsides, though, including:

  • Sun exposure causes furniture or carpets to fade faster

  • Loss of heat during winter

  • Loss of cool air during summer

Weigh the pros and cons and consider how much sun your home gets when deciding if you want a skylight.

15. Plumbing Vent

Many homes have a roof plumbing vent, also called a plumbing vent stack, which helps alleviate pressure from building up in your plumbing system.

When a plumbing system has poor ventilation, water, and even waste can get backed up in your pipes more easily.

Slow drains could be a sign that your plumbing vent is clogged, which may require a professional. If you do it yourself, it’s a two-person job—someone will need to turn on the water while you’re on the roof.


What are the four main parts of a roof?

The four main parts of a roof are the rafters, decking, underlayment, and covering. Rafters are the innermost frames that make up the basic structure of a roof. Decking boards connect to rafters and provide a level surface for the roof's covering (more on that later). 

Underlayments cover the decking boards to help insulate your home and protect against the elements. Finally, the roof's covering is the outermost part of the roof. It can be made of various materials, including asphalt shingles, metal, clay, slate, or concrete.

What are roof edges called?

The edge of a roof is called an eave. It overhangs past the exterior wall line at the bottom of a roof's slope. The two parts of an eave are the soffit and the fascia.

Need professional help with your project?
Get quotes from top-rated pros.