If you need a roof replacement, you need to learn how a roof is made up. When I say “made up,” I’m talking about the different materials and components that make a roof a roof. 

You’re probably thinking, “I know a roof has shingles, but how much more can there be?” The truth is, your roof is so much more than just the shingles (or other roofing material) you see. 

At Bill Ragan Roofing, we use our 30 plus years of expertise in the roofing industry to help homeowners like you understand the anatomy of a roof. Once you learn the anatomy of a roof, you’ll know exactly what you’ll be paying for when the time comes for a replacement. 

This article won’t cover the general construction aspect of a roof and home, like rafters or trusses. We’ll be covering the different layers (anatomy) of a roof, so you’ll learn the actual materials you’ll be dealing with during a replacement. 

Roof decking 

The first layer of your roof will always be your roof decking (also known as roof sheathing). Roof decking is the foundation for the rest of your roofing materials and components to be installed on.

roof decking

It’s made up of wooden boards (plywood or planks) that make up the framing of your entire roof system. If your roof’s decking is rotten or the integrity of the wood compromised, it’ll need to be replaced before the rest of the materials are installed. 

However, your roofing contractor won’t know if or how much decking will need replacing until they finish the tear-off process

Drip edge

Drip edge is metal flashing installed at the roof’s edges (eaves and rakes).

drip edge

Its main purpose is to keep water away from your fascia and from getting underneath your roofing components. Without drip edge, water will get behind your gutters and rot out both your fascia board and roof decking.

To avoid this happening, the IRC (International Residential Code) made it a code that your roof must have drip edge and that it’s installed correctly.

Unfortunately, some roofing contractors still ignore the code by leaving off drip edge to lower their prices or are too lazy to install it correctly. If this happens, it will be a lot harder to pass a home inspection because your roof isn’t up to code.

Ice and water shield

Ice and water shield is a waterproof membrane used to protect your roof from ice and water damage. It protects your roof decking if water gets underneath your roofing material (asphalt shingles, metal roof, etc.).

ice and water shield in a valley

Ice and water shield should be installed on/around certain areas of your roof, like roof valleys, around penetrations, and on roofs that have a 2/12, 3/12, or 4/12 pitch. Because of its importance, every roof needs to have it.

Roof underlayment 

Roof underlayment is a felt (15 lb, 30 lb, or synthetic) roofing material that lays between your roof decking and your shingles. It’s installed directly over your roof decking and provides an extra layer of protection from the elements.

roof underlayment

Underlayment is the last line of defense for your roof’s decking if water gets underneath your shingles. Because of its importance, you need to invest in the best underlayment possible. 

Starter shingles

Starter shingles are a pre-cut row of roofing material that goes underneath the first course of shingles before they’re installed.

starter shingles

It makes sure that there's protective material between the joints where the shingles butt against each other on the edges of your roof. 

Starter shingles also have an adhesive to ensure the first row of shingles is sealed at the edges of your roof. This adhesive seal improves your roof’s resistance to strong winds.

The roofing material you choose

Your roofing material makes up the bulk of your roof and is what most people think of when talking about a roof. Common roofing materials include asphalt shingles, metal roofing, cedar shake roofing, synthetic roofing, and slate roofing.

roofing materials

Because it makes up the bulk of your roof, it has a big impact on your home’s curb appeal. You can even raise your home’s value when going with a premium roof system (cedar shake, synthetic, slate). 

If you’re unsure what type of roof fits your needs, take this Roof Type Quiz to find the right roofing material for you. 

Roof flashing

Roof flashing is a thin metal material that directs water away from certain areas (walls, chimneys, roof valleys) of your roof. Every roof needs to have flashing to ensure water won’t get into your home. 

roof flashing

Your roof flashing will be made of aluminum, steel, or copper. No matter what kind of metal it’s made of, your roof flashing should outlive the original roof it was installed on. 

This means you might not have to replace it when getting a new roof. However, it’s crucial that your roof flashing is inspected as part of annual roof maintenance to prevent or catch potential leaks.

Ridge capping

After your shingles are installed on all facets of your roof and meet at the ridge, it’ll be time to install the ridge capping. Ridge capping is the trim material installed at the top of where two slopes of a roof meet. 

ridge capping

Ridge capping will be thicker than regular shingles and pre-bent so that they can form to the ridges on a roof. However, some roofing contractors use 3-tab asphalt shingles as ridge capping to cut down their costs for an asphalt roof. 

Because 3-tab shingles aren’t designed for this, it will lead to a roof leak. That’s why it’s crucial to use the manufacturer’s ridge capping accessory when getting a dimensional or luxury asphalt roof. 

Roof vents

Roof vents allow your attic and home to breathe properly. Without a proper attic ventilation system, your roof’s life will be cut drastically short. 

There are different types of roof vents to choose from depending on your ventilation system. If you have an active ventilation system, you’ll choose turbine vents, power vents, ridge vents with a baffle, or solar-powered vents. 

turbine vent(Turbine vent)

For a passive ventilation system, you choose from static vents (box vents), ridge vents without a baffle, or gable-end vents. I recommend an active ventilation system for performance reasons. 

box vent(Box vent)

However, all the vents do the job if they're installed properly, and your attic is properly ventilated. 

The 3 reasons you need to invest in quality roofing materials

Now you know the anatomy of a roof and what you need to know about each material. Every piece of your roof performs a specific function to keep you and your family dry. 

However, you can’t count on your roofing materials and components if they fail. That’s why it’s crucial to invest in quality instead of trying to find cheaper options. 

But this is just one reason you need to invest in quality materials. To help you avoid wasting your hard-earned money, we wrote another article breaking down the 3 ways a cheap roof will cost you more in the long run. 

Since 1990, the team at Bill Ragan Roofing has seen too many homeowners in Nashville have their roof investment ruined by cheap labor and materials. That’s why we try to educate homeowners like you, so they’re able to get the most out of their roof replacement. 

Check out 3 Ways "Cheap" Roof Systems Cost More in the Long Run to learn what happens when you don’t invest in quality roofing materials and components.

checklist of questions to ask a roofing contractor