The Parts Of A Roof: 5 Major Parts And What They Do

Posted on May 25, 2023

The Parts Of A Roof: 5 Major Parts And What They Do

Today, we’re going to be discussing the five major parts of a roof and what they do. Whether you’re a homeowner or a contractor, understanding the parts of a roof is essential for maintenance, repair, and installation. 

Here in Louisiana, roofs come in a variety of shapes and sizes. From flat roofs and gabled roofs to shed roofs and gambrel roofs, there’s a roof design out there for every home. But no matter the size or shape of your roof, all roofs have five major parts: the deck, the underlayment, the flashing, the shingles, and the roof vents. Each of these parts has its own function and purpose, and together they form a reliable barrier between you and the great outdoors. 

In this blog post, we’ll be exploring the five major parts of a roof and what they do. Stick around, and you’ll learn everything you need to know about your roof, from the deck and underlayment to the ridge cap and flashing. So what are you waiting for? Let’s get started!

5 Major Parts Of A Roof And What They Do

The roof comprises several major parts, each specifically protecting and maintaining the structure’s integrity. Here are the five key roof parts and their functions:

#1 Roof Decking

Roof Deck

The primary function of the roof decking is to provide a stable and solid base that supports the weight of the roof materials and distributes it evenly across the roof structure. The roof decking acts as a platform onto which the waterproofing layers are applied, protecting the underlying structure from moisture infiltration.

It is typically made of plywood or OSB and provides a stable and solid base for the other roof components while contributing to the structural integrity of the entire building.

#2 Underlayment


Roofing Underlayment is a layer of material installed on the roof deck, beneath the visible roofing material. It prevents moisture from penetrating the roof decking by acting as a barrier and adding an extra layer of protection. 

Traditionally, the underlayment was made of asphalt-soaked felt paper. However, synthetic underlayment has become more popular due to its enhanced durability and performance. Synthetic underlayment is often made of polypropylene or polyester, which is better at resisting tearing, water, and UV radiation.

Choosing an appropriate underlayment for your specific roofing system is essential in order to provide adequate protection against moisture.

#3 Roofing Material

Nothing is more important than having an outer roofing material that can keep a building and its inhabitants safe from the elements. It acts as a waterproof barrier, shielding against rain, snow, wind, and sunlight while preventing water infiltration and moisture damage. They also contribute to the aesthetic appeal of a building, enhancing its architectural style and visual impact.

The type of roofing material you choose depends on your local weather, building design, budget, and personal preference. When selecting the best roofing material for a building’s needs and style, it’s important to consider how long it will last, how much maintenance it will need, how energy efficient it is, and what the local building codes are.

Roofing Material

Types Of Roofing Materials

Asphalt Shingles: Asphalt shingles are the most common and widely used roofing material. Composed of asphalt and covered with ceramic granules, they provide affordability, ease of installation, and versatility in various architectural styles.

Metal Roofing: Aluminum, steel, copper, and zinc are metal roofing materials. Metal roofs are strong, lightweight, and weatherproof. They can be installed as shingles or panels, and are preferred for their durability and energy efficiency.

Clay or Concrete Tiles: Commonly found on Mediterranean and Spanish-style homes, clay and concrete roof tiles are elegant and unique. They can withstand extreme weather and fire, and provide great thermal insulation. 

Wood Shingles or Shakes: Cedar, redwood, or other treated wood is used to make wood shingles. They provide a natural, rustic appearance and are valued for providing adequate insulation. Wood roofs need regular maintenance to prevent decay and are often used in historic or traditional architectural styles.

Slate: Slate roofing is famous for its beauty, durability, and longevity. It is a natural stone that resists fire and impacts while lasting for decades. Slate roofs add elegance and sophistication to luxurious or historic buildings.

Synthetic Roof: Synthetic roofs mimic wood, slate, and tile but are more durable and low-maintenance. Synthetic slate, polymer shakes, and composite shingles are just a few examples.

#4 Flashing

Flashing is an essential part of a roof that prevents water infiltration in vulnerable areas where the roof meets other structures or features. It is typically composed of thin, durable metal, such as aluminum or galvanized steel, and is installed strategically.

You will typically find flashing installed along roof intersections and valleys, such as chimneys, vents, and skylights. It helps ensure a watertight seal and diverts water away from these critical areas.


Types of Flashing

Step Flashing: Typically, step flashing is installed around vertical roof penetrations, such as chimneys or walls. Individual metal pieces are installed in a staggered pattern, overlapping one another and the adjacent roofing components to form a watertight barrier.

Valley Flashing: Valley flashing is installed where two roof slopes meet to create a valley. It helps direct water away from the roof and down the valley. For valley applications, valley flashing can be made of metal or specialized membrane material.

Drip Edge Flashing: Drip edge flashing is installed along the roof’s eaves and the rakes. It helps direct water away from the roof and into the gutters, preventing water from seeping underneath the roofing materials or causing damage to the fascia.

Vent Pipe Flashing: Vent pipe flashing covers roof-penetrated plumbing vent pipes. A rubber or metal boot fits tightly around the vent pipe, and a metal base is secured to the roof. This vent pipe flashing creates a watertight seal.

Skylight Flashing: This is a set of metal flashing pieces made to fit around the shape of the skylight. This makes sure that there is a good seal between the skylight frame and the roof.

Wall Flashing: Wall flashing protects the space between where a roof meets an outer wall, like parapet walls or sidewalls. It seals the roof-wall intersection to prevent water from entering the wall cavity.

#5 Roof Vents

Roof Vents

Roof vents are a vital aspect of a well-functioning roofing system that involves air circulation between the interior and exterior of the roof and attic space. It plays a crucial role in maintaining a healthy environment, controlling moisture levels, regulating temperature, and promoting energy efficiency. Roof ventilation allows fresh air to enter the attic while expelling stale air and moisture.

Factors such as attic size, climate, and local building codes all play a role in determining the exact ventilation needs. Maximizing the benefits and guaranteeing the long-term performance and durability of a roof depends on the proper design and installation of ventilation systems.

These are just a few of the most important parts of a roof. The exact parts may vary depending on the type of roof, and how roofs are built in a certain state. Talking to a roofing professional is important if you want to know more about your specific roofing system.

Types of Roofs

Now that we’ve covered the essential parts of a roof, let’s have a look at the unique characteristics and aesthetic appeal of different types of roofs. Here are some common types:

parts of a roof

Gable Roof: A gable roof is a classic triangular-shaped roof with two sloping sides that meet at a ridge. It is known for its simplicity and effective water drainage.

Hip Roof: A hip roof has slopes on all sides, gently sloping towards the walls. This design offers stability and is resistant to strong winds.

Mansard Roof: The distinctive feature of a mansard roof is its double-sloped design. The lower slope is steep, while the upper slope is almost flat. It provides extra living space and is commonly seen in French architectural styles.

Flat Roof: As the name suggests, a flat roof looks flat, but does have a slight slope. It is commonly used on modern and commercial buildings and allows for easy installation of rooftop features like solar panels.

Gambrel Roof: A gambrel roof has two slopes on each side, with the lower slope being steeper than the upper slope. This style is often associated with barns and Dutch Colonial-style homes.

Shed Roof: A shed roof is a single-sloping plane that slopes downward in one direction. It is simple in design and often used for sheds, garages, and contemporary-style homes.

Sawtooth Roof: Commonly found among industrial buildings, a sawtooth roof consists of a series of ridges with vertical glass or translucent panels. It maximizes natural light while providing effective ventilation.


At the end of the day, your roof is the most important component of your home. It serves as a protective layer to keep your family and belongings safe from the elements. That’s why it’s essential to understand the importance of each part of a roof, and how they work together. With this knowledge, you can make informed decisions, ensure proper maintenance, and enjoy the benefits of a secure, durable, and comfortable shelter for years to come. 

When you’re ready to take the next step towards roof repair or replacement, get in touch with Empire Roofing & Exteriors. Our team of roofing contractors is here to help you protect your home and take care of all your roofing needs in Baton Rouge, LA. Contact us today to set up a consultation, and let us help you get the most out of your roof (225) 347-8877.