The Anatomy of a Roof: A Homeowner’s Guide

It might seem simple from the outside, but a lot goes into a roof to protect your property. You can think of a roof as a system of many pieces that all work together to endure impacts, channel water, regulate temperature, add structural integrity, seal joints that may otherwise become leak points, and plenty more.

To help homeowners understand how their “roof system” works, we’ve created a glossary that covers many of its most important pieces. You can think of it as the basic anatomy of your roof, along with a few additional features that provide specialized protection against the tough conditions Texas throws at it.

We’ll focus on three categories:

1. Essential Structural Elements
2. Weatherproofing Additions
3. Shape and Regions of Roof

1. Structural Elements of a Roof

Before the most visible parts of a roof can be put into place, the support beams and other structural components must be installed. These elements form the skeleton of the roof which makes exterior components like siding, trim, gutters, and a roof covering possible. In this section, we’ll explore the skeleton of the roof as well as the essential components it supports.

Rafters

You can’t get much more foundational than rafters. Imagine a classic triangular roof: rafters are the diagonal support beams that create that “A” shape. This is the skeleton, or frame, of the roof, which will support the weight of all other roof layers, including decking, underlayment, and coverings. Due to the simplicity of rafters, there’s often “room” left available for an attic space.

Texas Homeowner Tip: The design of your rafters determines the slope and structural strength of your roof. The slope will affect how well the roof sheds water and handles snow or debris, while how well your rafters distribute weight to your home’s walls will affect how stable the structure is during heavy storms or high winds.

Trusses

Today, trusses are more common than rafters. You can think of trusses as an alternative way to create the frame of your roof. Rather than using rafters to create a simple “A” that distributes weight down to the home’s walls, trusses are prefabricated structures with a wooden “webbing” that provides more support for the roof so it can span a larger area and minimize the risk of sagging. 

Texas Homeowner Tip: Because trusses are prefabricated, they tend to be less expensive than having rafters built on site. Trusses also open up design opportunities, such as open floor plans which require a roof frame that can support itself with fewer interior walls. However, trusses will eliminate attic space and limit ceiling design options.

Decking

Decking, sometimes called sheathing, can be thought of as the base of the roof. It’s the flat layer of plywood or oriented strand board (OSB) that spans across your rafters or trusses to create the surface that holds roofing materials. It’s a bit like muscles stretching over bones to provide rigidity to the body.

Texas Homeowner Tip: High-quality and well-maintained decking is essential to keep your home safe from Texas rainstorms and hail. Strong decking will prevent roof sagging and resist impacts that could cause cracks and thus leaks into the rest of the home. As such, you should opt for OSB, the stronger material, over plywood when possible.

Underlayments

Underlayments are moisture-resistant or waterproof layers installed directly over the roof decking. If your roof covering is damaged, underlayments act as a critical barrier against water leaking into more vulnerable wooden areas.

Texas Homeowner Tip: The Lone Star State’s heavy rain, rough storms, and high-impact hail mean a solid underlayment is a must. Consider “Ice and Water Shields,” which are specifically designed to prevent leaks in vulnerable areas, as well as “Peel-and-Stick” membranes which adhere without staples or nails, which might otherwise create leak points.

Roof Covering

This is the part of the roof you’re already familiar with! The roof covering is the most weather-exposed part, made up of shingles, tiles, metal sheets, or other materials. This layer protects the home from rain, wind, sun, hail, snow, wind, and other elements.

Texas Homeowner Tip: Choosing the right roof covering is essential to protecting your home. We’ve already created a multi-part series exploring the pros and cons of every major roof covering. For more information, start reading our Choosing the Right Roof Guide. Homeowners should choose coverings based on their climate and budget, as this component directly affects the roof’s lifespan and performance.

Drip Edge

A drip edge is a metal strip installed along the edges of the roof that makes sure water is directed into the gutters rather than running below the roof and seeping into the underlying wood.

Texas Homeowner Tip: Texas gets plenty of rainstorms, so a drip edge is a smart investment. Not only will it reduce deterioration of the fascia (which we’ll cover next) and inner wall from water running off the roof but also from wind-driven rain that impacts your home from unexpected directions.

Fascia Boards

The fascia is the long horizontal board that connects the lower rim of your roof to your home’s outer wall (or if you have an overhang, to soffits). Not only do fascia aesthetically “clean up” the edges of the roof, but they also protect the lower ends of roof rafters or trusses from the elements and support the weight of gutters.

Texas Homeowner Tip: Maintaining the fascia is essential. If the boards are damaged, water can infiltrate the exposed wood behind it leading to rot and costly repairs.

Soffits

If your roof has an overhang, soffits can be used to protect its underside, shielding the home’s structure from rain, wind, and pests. Soffits are also a common location for vents, which can regulate the temperature and humidity within your roof and attic space.

Texas Homeowner Tip: Homeowners in hot or humid climates like Texas should pay attention to soffit ventilation. Ventilated soffits provide airflow to the attic to help prevent mold growth and deterioration due to heat and humidity.

Frieze Boards

Frieze boards are trim pieces that connect the lower edge of a roof to the siding. Aesthetically, they “clean up” the appearance of the joint where the roof intersects the siding. Functionally, they shield the inner wall from water damage and wear.

Texas Homeowner Tip: Small components like frieze boards may seem less important, but they’re a vital part of the roof system. Without them, water can infiltrate the joint between the roof and walls and cause damage behind the scenes.

Siding

While primarily a wall component, siding often overlaps with the roof, working in tandem with fascia and soffits to protect the home’s exterior. In this way, siding plays an important role in shielding vulnerable areas left unaddressed by other roof components.

Texas Homeowner Tip: When you think about roof durability, siding might not be the first thing that comes to mind. But siding is key to sealing gaps where the roof meets walls so water doesn’t seep inside.

Trim

Trim refers to all the small “finishing” elements that functionally seal and aesthetically “clean up” the edges of the roof.  Trim is yet another layer of protection that closes gaps to shield the vulnerable interior of the roof from the elements.

Texas Homeowner Tip: Spaces around fascia, soffits, and siding can be closed by trim to create a seamless appearance to increase curb appeal — and prevent water intrusion and pest infestations.

2. Weather-Proofing Roof Additions

Now that we understand the basic structural elements of a roof, let’s talk about additional components that help roofs endure their unique environments. As we discussed in our guide to the best roof for Texas weather, the Lone Star State is known for its high heat, heavy rain, hailstorms, and strong winds. That means Texas homeowners need roofs that can withstand these conditions to keep their homes safe. In our infographic, we’ll explore a few weather-proofing additions that accomplish just that.

3. Parts of the Roof’s Surface

Certain regions of a roof’s surface are uniquely vulnerable to damage and require special attention. That’s why, in this section, we’re going to provide a vocabulary to identify and describe common features of a roof’s surface and understand what role they play and their vulnerabilities.

Ridges

Just like a mountain ridge, the ridge of a roof is where two planes meet at the highest point. Due to their height, ridges are a key location for ventilation, allowing warm attic air to rise and exit through ridge vents. These are often the most prominent parts of a roof—the highest point that may be visible from down the street. 

Hips

While ridges are the highest point where two planes meet, hips are the diagonal slope where two points meet leading up to the ridge. You can think of hips as the sides of a triangle that meet at a point. Hips help water flow smoothly off the roof, reducing the likelihood of pooling and leaks.

Valleys

Valleys are the internal angles where two roof slopes converge—much like a valley at the base of a mountain. This forms a channel that directs water and debris off of the roof. Because runoff naturally collects in valleys, this is a particularly vulnerable region of a roof. Without proper flashing and maintenance, basic elemental deterioration could lead to leaks.

Dormers

When you see a windowed section of a roof protruding from the main roof, you’re looking at a dormer. Dormers are a great way to bring light into an attic and create additional interior space. They can also improve curb appeal by creating a more dynamic roof. Due to the added complexity of dormers, they require additional attention regarding sealing. 

Parapets

More common in commercial and urban residential buildings, parapets are low walls erected at the edges of flat roofs.  Not only do they help prevent falls, but parapets can also channel water toward drainage systems to prevent pooling and protect the building’s foundation from erosion.

Gables

Common to residential homes, a gable refers to the wall beneath a roof’s sloping sides. For instance, imagine you’re standing in front of a house and you see windows on the first floor, the second floor, and then an attic window surrounded by siding. That attic window is located within a gable. Beyond improving curb appeal, gables are a common location for attic ventilation, which can improve airflow and thus temperature and humidity control.

Fields

Fields refer to the broad, flat sections of the roof between ridges, valleys, and hips. These areas bear the brunt of weather exposure, making the quality of roofing materials used here crucial. Homeowners should prioritize durable coverings for the fields. After all, they’re the roof’s first line of defense against rain, wind, and hail.

Eaves

Eaves are the edges of the roof that extend beyond the walls, offering shade and protection to windows and siding. They can also play a key role in water management by directing runoff away from the home’s foundation. Properly installed and maintained eaves are essential for preserving the structural integrity of the entire house.