What are the different parts of a roof that homeowners need to know?

While roof shingles are the stars, our experts highlight the unsung and unseen hero roofing parts of your home, essential to a leak-free system.

Likewise, we ranked each roofing part in terms of importance based on decades of real roofing data from roofs we’ve personally inspected or replaced.

From fascia, soffits (aka eaves), flashing, and gutters to roofing layers like decking and underlayment, you’ll learn them all accompanied by real photos of each roof part.

Because when you know each part of your roof structure, you’ll be able to spot bad roofing contractors versus the best roofing companies.

In the same vein, here’s our guide on exactly how to tell if a roofer is lying to you.

21 Most Important Different Parts of a Roof System (Labeled Diagram)

Here is a diagram of the different parts of a roof terminology, with a labeled list below in order of importance to homeowners.

Select any of the roofing parts labeled below to jump to a detailed breakdown and photo example of each kind of roof structure.

Our Roofing Part Ranking Methodology

Located in Downers Grove, IL, HomeHero Roofing is one of the fastest-growing and highest-rated residential roofing companies in the country.

Over the past year, we took a survey of the most important parts of a roof to determine the key structures you need to know as a homeowner.

An overview of the results can be found in the roofing part diagram chart below.

In our study, we tracked how often each part of a roof needed repairs or led to full roofing replacements.

Additionally, we counted the number of times the homeowners we served asked about the definition of each roof part during and after estimates.

Combining these data points, we determined that asphalt shingles are most often the cause of roof issues or most asked about when it comes to the parts of a roof.

1. Asphalt shingles

Asphalt shingles are the most popular residential roof covering because of their durability and affordable cost.

Made from a fiberglass mat coated with UV-resistant mineral granules in various colors, they protect and beautify your home exterior.

Here are the 11 most trend-worthy roof shingle colors of the year, based on overall popularity.

Directly underneath shingles, you’ll find underlayment, or depending on local building codes, flashing or an ice and water barrier.

As showcased above, each shingle overlaps with the others to protect your home from rainwater, storms, snow, and hail.

The three types of shingles, from cheapest to most expensive, are three-tab, architectural, and luxury shingles.

In general, the higher the price, the longer asphalt roofs will last. For example, luxury shingles last 25-30 years on average, compared to 20-25 years for architectural shingles.

Learn about how long the average residential roof in Illinois lasts compared to other states in our recent study.

2. Roof underlayment

Your roof’s underlayment sits directly under your shingles, just above your ice and water barrier and roof sheathing (aka decking).

When shingles fail or are damaged by wind, hail, or storms, underlayment waterproofs the easy-to-rot roof decking below it.

Here’s another example of underlayment installed below shingles but above wood decking layers on a roofing job in Westmont, IL.

As a reference, the ice and water barrier is a type of underlayment installed in key parts of roofs in areas with cold winters. More on this later.

Without underlayment, your roof is at risk of major structural damage from water leaks. It’s essentially a water-resistant barrier made of felt, synthetic polymers, or rubber that protects the wood decking or sheathing.

Not to mention, it provides insulation and a stable surface for shingles to be installed on.

3. Ventilation pipes and roof vents

No question, proper ventilation is essential for a healthy roof system, no matter the roofing material or type of roof.

Roof vents release hot and moist air from being trapped in your attic, and allow cool, dry air in to extend how many years your roof lasts.

There are few types of roofing vents that have different functions, but all are designed to increase air flow, preventing costly repair work. A few popular types are exhibited below.

• Metal roof cap or exhaust vent: tall pipe that lets stale or humid air from inside the house escape through the roof while keeping rain out
• Static dome vent (attic vent): passive attic exhaust that releases hot, trapped air to help shingles and insulation last longer
• Plumbing vent stack: vertical pipe that vents plumbing and sewer gases and keeps water flowing to home’s drains
• Ridge vents: type of hip and ridge cap shingles installed on roof peaks allowing warm attic air to exit evenly across roofs

Warm air rises through your ventilation pipes and cool air circulates via your soffit vents or gable vents, preventing mold and regulating attic temperatures.

Again, without vents, your rafters, trusses, attic, and decking will deteriorate or warp, leading to severe water damage. Learn more about how attic ventilation works.

4. Roof decking (aka roof sheathing)

Roof decking (also called roof sheathing) is the structural, wooden base layer that creates a flat surface on which shingles or metal roofing sit.

However, you’ll want to make sure that either sheathing or an ice and water barrier is installed on top of decking before nailing any shingles to a roof.

In the above photo, you can see the wood decking of this roof is the base layer part that sheathing or ice and water barriers are installed on top of.

Typically made of plywood sheets or oriented strand board (OSB), it acts as a stable barrier, adding both insulation and some soundproofing.

Learn more about the different types of wood decking on residential houses.

5. Ice and water barrier

Required in cold-weather cities like Chicago, ice and water barriers are a type of water proof membrane underlayment that protects the most vulnerable parts of your roof.

Also called ice and water shields, they prevent ice-dams and leaks caused by wind-driven rain, adhering directly to decking, installed on a roof’s edges.

In Illinois, residential roofing codes specify that ice and water barriers need to be installed 24 inches up from the eaves along your home’s exterior wall and at valleys.

Keep in mind that some towns, like Lombard, IL, require 18 inch wide ice and water shields on each side in valleys, so check your local roofing structure codes.

Just remember that underlayment must overlap the ice and water barrier and that drip edges are required on all eaves and rakes.

6. Drip edge flashing and metal roof flashing

Flashing refers to a thin piece of metal that diverts water away from vulnerable areas of your roof.

Most important of all, drip edge flashing is installed around the perimeter, below shingles and ice and water barriers, to allow water to drip off into the gutters.

Show above as a reddish strip just under the shingles, drip edge flashing is the metal or vinyl lip installed along the eaves on the perimeter edge of homes.

It prevents water from hugging the edge of shingles and getting underneath them, which will eventually rot fascia and wood decking.

For new roof replacements, drip edges are required as an added layer of protection from water leaks.

7. Rafters or trusses

Rafters and roof trusses act as the structural skeleton for your roof, giving it shape while supporting its weight.

Both support everything above them: decking, underlayment, shingles, and snow loads during harsh Illinois winters, but in different ways.

As you can see below, roof rafters are the individual beams that run angled down from the peak to the soffits or exterior walls. On the roof below, located in La Grange, IL, rafters form a triangle outline and shape the plane of the system.

When it comes to roof repairs or structural damage, rafters are more flexible and easier to repair versus trusses in many cases.

However, because they are more difficult to install, they can be prone to leaks and require more frequent repairs than trusses.

On the other hand, trusses are pre-engineered triangular frames designed to distribute the roof’s weight evenly.

Show above in an attic of a home in Hinsdale, IL, trusses are found on newer roofs because they are easier to install than rafters. This makes trusses less prone to human error during the install, leading to less repairs over its lifespan.

In general, if either rafters or trusses get damaged from moisture, pests, or poor airflow, it can cause sagging rooflines or costly structural damage.

Keeping your attic dry and well-ventilated helps protect the entire framework of your roof system.

8. Attic insulation

Attic insulation keeps warm air inside during cold Chicago winters and blocks heat from building up under your shingles in the summer.

No question, it plays a significant role in how well your roof performs year-round and the overall lifespan, keeping your attic dry and energy-efficient.

Remember that attic insulation should be installed on the attic floor versus directly under the roof deck and between trusses, unless its a finished attic room.

Luckily the interior attic above of a house in Woodridge, IL, has adequate attic insulation, which led to lower heating and cooling bills for the homeowner.

Without proper insulation, your attic turns into an oven in July and a freezer in January, both of which shorten your roof’s lifespan.

The best way to do this is to have a roofing contractor inspect the inside of your attic whenever they come out for an estimate.

9. Hip and ridge cap shingles

Hip and ridge cap shingles protect the very top edges of your roof where two slopes meet. They seal those joints from water while providing a clean, finished look.

Because these spots take the brunt of sun, wind, and snow on a pitched roof, they are made thicker and more flexible than regular shingles.

Detailed later in our list, ridge vents are a type of hip and ridge cap shingles that provide ventilation for attics.

Over time, caps that crack or curl can let water sneak under your roof system, especially during Chicago’s windy storms.

No question, replacing worn ridge caps is a simple but essential maintenance step, keeping things watertight and looking sharp.

10. Gutters and downspouts

Both gutters and downspouts work together to move rainwater safely off your roof and away from your home’s foundation.

Gutters catch the water running down your shingles, while downspouts carry it to the ground and out into your yard or drainage system.

Our data show that 62% of residential roof replacements performed by homeowners in Chicago’s western suburbs, include replacing gutters as part of the project.

When leaves or debris clog up gutters or downspouts, water can back up under shingles, rot fascia boards, or pool around your foundation.

Keeping your gutters clean and your downspouts extended several feet from the house prevents leaks, basement flooding, and long-term roof damage.

As a final tip, installing gutter guards is the most effective and cheapest way to keep gutters clean each year.

Typically made of metal or mesh, gutter guards are most affordable when installed as part of a full roof replacement project.

11. Ridge vents

Found at the highest points of a roof, ridge vents run across the peak of your roof and are key to keeping your attic dry and cool.

They allow hot, humid air to escape from the top or roof ridge while allowing fresh air to flow in through the soffit vents below.

That steady airflow helps prevent mold, wood rot, and ice dams, all common issues in Chicagoland homes.

Above, you can clearly see the ventilation grates below the lip of the ridge vents installed on this recent roof replacement job we did in Naperville, Illinois.

Now, if your attic feels stuffy or you notice condensation on rafters each season, your ridge vent might be blocked or missing altogether.

A properly installed ridge vent helps balance your attic’s temperature year-round, reducing energy costs and extending the lifespan of your shingles.

12. Eaves or soffits

Eaves, also called soffits, are the undersides of your roof’s overhangs. Essentially, eaves are the horizontal line you see when you stand under the edge of a roof and look up.

They play a significant role in ventilation, allowing cool air to enter the attic through small vents that work in conjunction with you ridge vent to keep air circulating.

In the diagram below, the soffits or eaves are the brown underside surface and fascia is the white strip or board facing out on this garage roof in Darien, IL.

When soffits become blocked or damaged, attic temperatures rise, moisture accumulates, and ice dams form more easily in winter.

Clean, ventilated soffits or eaves help your roof breathe and protect your rafters from rot or mold caused by trapped humidity.

Luckily, soffit vents, which are number 18 on our list here, help with this. We’ll go into detail on these nifty but often misunderstood roofing parts soon.

13. Fascia

Fascia boards run horizontally along the outer lip of a roof, right behind the gutters.

An easy way to remember is that “fascia” are the trim or boards that are “facing you”.

They provide a clean, finished look and act as a strong mounting point for your gutters while sealing off edges from water and pests.

Most times, fascia boards are painted wood or capped with vinyl. If fascia boards start to rot or pull away, it’s usually from overflowing gutters or trapped moisture.

Replacing or repainting damaged fascia regularly not only improves curb appeal but also prevents water from sneaking under your roofline. Find out what siding colors look best with brown roof singles.

Not to mention, maintained fascia allows drip edge flashing, gutters, and downspouts to all function together to properly drain water away from your house.

14. Roof rake

The roof rake is the sloped edge that runs from the ridge or peak down to the eave, usually along the gable ends of your home.

As an example, there are no rakes on flat roofs.

It’s designed to help direct rainwater and snow off, rather than letting it collect near the edges.

Because it’s exposed to wind and weather, the rake edge needs proper drip edge flashing to prevent leaks.

In snowy Illinois winters, it’s also smart to use a roof rake tool to clear heavy snow buildup and reduce the risk of ice dams.

Discover how much a roof costs in Chicago or Illinois state-wide, the different in numbers may surprise you!

15. Skylights

Skylights bring natural light into darker areas of your home and make rooms feel more open and airy.

They’re installed directly onto wooden decking and sealed with flashing to keep water out while letting sunlight in.

The diagram above highlights a few skylights of a home in downtown Downers Grove that our professional roofing crews completed last season.

However, roof skylights are also common leak points if not flashed or sealed correctly.

With this in mind, regular skylight inspections help ensure the seals stay tight and debris doesn’t collect around them.

16. Dormers

Dormers are the small roofed structures that project from your main roof, usually housing windows or adding headroom to attic spaces.

Not only do they bring natural light and ventilation to upper floors, but they also add more character and curb appeal to your home.

Since roof dormers interrupt the main roofline, they require precise flashing and sealing where they meet the larger roof.

Poor installation or worn flashing can easily cause leaks around dormer walls, so regular inspections are key before Chicago’s heavy rain or snow season.

Check out this helpful guide from Owens Corning outlining how each part of roofing systems work together.

17. Ceiling joists

Ceiling joists are the horizontal beams that tie your roof’s structure together, forming the base of your attic floor and helping distribute the roof’s load across your walls.

They also serve as the foundation for drywall or ceiling materials inside your home, acting as the bones or skeleton of your house.

Keeping your attic dry, insulated, and well-ventilated helps prevent this kind of damage and ensures your entire roof framing stays stable for decades.

18. Soffit vents

Roofing soffit vents are small openings installed under overhangs that let cool air flow into your attic.

They work hand-in-hand with ridge vents to create balanced ventilation that keeps your roof from overheating or collecting moisture.

Pro tip: Avoid painting over your soffit vents when refreshing your soffits or eaves with a roller, which can clog ventilation holes completely.

Instead, ask your painter to apply a thin coat with a professional paint sprayer on soffit vent areas, allowing the vent grates to breath properly.

Without functioning soffit vents, your attic can trap heat and humidity, leading to warped decking, mold, or ice dams in winter.

Remember to clear out any debris or insulation from vents each Spring and Fall so fresh air can circulate freely year-round.

if left unchecked, clogged vents can lead to interior moisture buildup. Over longer periods of time, this may even become a fire hazard.

19. Roofing hips and valleys

Hips and valleys are where two roof slopes meet. Roofing hips run outward on raised ridges, while valleys dip inward where slopes intersect.

An easy way to remember is that hips jut out and valleys bow in. Check the image below for a diagram example of valleys and hips on a roof we replaced in Burr Ridge, IL.

No doubt, these are some of the most critical areas of any roof because they handle large volumes of water runoff.

That’s why, based on our study, hips and valleys are often the areas of a sloping roof most prone to leaks. As a result, precise flashing and shingle installation are needed to prevent leaks in these danger zones.

Indeed, leaves, snow, and debris can collect in roof valleys, so keeping them clean helps extend your roof’s life and prevent hidden water damage.

Overall, getting a trusted local roofer to inspect your roof each year is a great way to spot issues like this before they get worse.

20. Sidewalls

Sidewalls are the vertical walls of your home that meet the edge of your roof, often around dormers, garages, or extensions.

These junctions need careful flashing to stop water from seeping behind siding or under asphalt shingles.

Over time, old or loose step flashing can allow rainwater to seep in, causing rot or interior leaks.

Re-flashing or resealing the sidewalls during roof maintenance is a simple way to prevent pricey repairs later.

Knowing this, you’ll better understand the term when a roofer mentions a sidewall during a roof inspection or quote.

21. Hip roof vs gable roof

Hip and gable roofs are the two most common roof styles you’ll see on homes in Chicagoland, and each has its pros and cons.

Shown above, a hip roof slopes down on four sides, meeting at the top to form a ridge.

This design makes it sturdier and better at shedding water and snow, ideal for Illinois weather.

On the other hand, a gable roof slopes down on two sides only. As highlighted below, these two sides meet at the peak, forming a triangle shape.

Generally speaking, gable roofs offer excellent ventilation and a classic look, but they’re a bit more vulnerable to wind damage because of those exposed peaks.

In short, hip roofs are more durable, while gable roofs are simpler and less expensive to install. However, both can perform great when built and flashed properly.

Find out what questions to ask a roofing company when deciding between repairing or replacing your old roof.

Terminology Parts of a Roof FAQs

When it comes to the most important parts of a roof terminology, it can get confusing for homeowners.

To make it easy, here are some of the most frequently asked questions answered in detail.

What’s the most confusing roof terminology for homeowners first dealing with contractors?

The most confusing terminology for homeowners dealing with contractors for the first time are when roofers use different terms to describe the same thing.

Here are a few of the most common roofing terms that trip folks up.

1. sheathing versus decking
2. soffits versus eaves
3. whether they have a gable or hip roof
4. different flashing types and their functions
5. joists versus trusses or rafters
6. ridge vents versus ridge and hip caps
7. ice and water barriers vs ice & water shields

Is roof decking and sheathing the same thing?

Yes, roof decking and roof sheathing are interchangeable terms for the same plywood or OSB sheets that are installed on the framing of a home.

What is the difference between hip and ridge caps and ridge vents?

Hip and ridge caps refer to the actual type of shingles that sit on top of ridge vents or in valleys.

More specifically, the “ridge” refers to the main peak of a home. Hips often extend off the main ridge and exist only on hip roofs.

Alternatively, ridges are located on both hip roofs and ridge roofs.

Are soffits and eaves the same thing?

Yes, soffits and eaves are the same thing. They’re interchangeable terms for the horizontal surface under the overhang located on the perimeter of most residential homes.

How is fascia different from eaves or soffits?

Fascia refers to the vertical trim boards located right above soffits, typically behind gutters of a home.

As a reference, fascia is the wood or vinyl capped trim board that “faces you”. Its the surface that gutters are often fastened to.

Do ice and water barriers and ice & water shields refer to the same thing?

Yes, ice and water barriers are the same thing as ice & water shields. Both terms refer to the same type of underlayment installed along eaves and valleys.

Essentially, they prevent dangerous ice dams from forming overhead and creating a safety hazard in freezing temperatures.

More specifically, ice and water shields are required as standard roofing code in most cold-weather states like Illinois or Wisconsin.