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27 Technical Parts of a Roof and Their Purposes

The roof is one of the most recognizable parts of a home. Its task is to protect it against nature’s elements like rain, snow, wind, and temperature extremes. It appears straightforward at first glance, but it’s much more complex than meets the eye.

The roof is more than its shingles, and it has a lot of complicated components that work together to provide enough protection for your home. In this article, we’ll talk about the parts of a roof and their functions.

Roof Structure

The roof components below are some essential parts of the roof that comprises it. These parts are critical to keeping the roof upright and ensuring that it will not topple over. Think of these parts as human bones that comprise the human skeleton, if you will. 

Most of these parts are made from wood but can vary depending on the homeowner’s choice or what direction the roofing professionals decide to lead the roofing project.

Roof Deck

A roof deck, roof decking, or roof sheathing is a structural foundation that serves as a base for the entire roofing system. While it may look like wood, it’s made from composite materials that can withstand heavier roof loads. 

Aside from adding extra protection between the roof and your home, a roof deck functions as a nail bed for the roof shingles and can increase the surface for the underlayment. The roof deck and the underlayment also work hand-in-hand to provide insulation for your home, ensuring that your attic space is moisture-free.


A rafter serves as your roof’s skeleton. The diagonally-shaped frames included in the roof truss serve as the primary support for the roof deck and any heavy load put upon it. It is where every part of the roof’s structure attaches itself, and without it, your entire roof will crumble into a heap of debris.

Roof Ridge

The roof ridge is technically the highest point on a roof where the two roof planes meet. It functions as an intersection where the roof truss and rafters meet to form the roofs. The roof ridge creates lateral stability for the roof and acts as a spine for the roof’s peak. The roof ridge uses a particular type of shingle called ridge shingles specifically designed for it.


If rafters are the vertical support beams, then the purlins are horizontal. They’re one of the roof’s supporting structures that binds the rafters together. Purlins are necessary to build a rigid roof, especially in Florida, where strong winds due to hurricanes are regular occurrences. Roofers typically install wooden purlins, but they can also use steel purlins because they remove the necessity for plywood roof decking.


The pitch is simply the slope of the roof. The ratio between the roof’s rise and its horizontal span is usually expressed in angle inclination. The purlins and rafters play a big part in determining the pitch of a roof. It’s also arguably the most noticeable feature of any roof.


Another part of the roof’s structure is the ceiling joists. This structural member is the parallel horizontal beam that spans from roof to roof. Its primary purpose is to carry the roof’s weight and typically run in the same direction as the roof rafters.


The truss essentially creates the roof’s frame. It is a series of interlocking structural parts like rafters and joists. Roofers must ensure that the truss is strong and contours to the shape of the homeowner’s house. Most residential trusses are made from wood, but steel trusses are available for those who want a roof with better structural integrity.

Roof Covering

The parts we’ll discuss below are responsible for adding a layer of protection not only for the underlying roof components but also for the house itself. Without these parts, the roof can’t protect your home the way it’s supposed to. You’ll see many parts below, so be careful to understand each piece slowly and carefully.


Shingles are simply the roof covering, typically in rectangular shapes. There are different types available, like clay, metal, and asphalt shingles. Companies specializing in manufacturing roofing materials like CertainTeed and Owens Corning create them. 

Shingles can overhang beyond the drip edge, but they shouldn’t extend by more than ¾”, lest they crack or break off. And although people think that they’re hazardous, they aren’t. Unless you try to collect potable water through the roof, that is.


The underlayment is the roof covering that acts as your roof’s last line of protection against water infiltration. It’s sometimes called an underlayment membrane, felt, or tar roofing. Roofers will use asphalt-saturated felt as an underlayment in most cases. 

But due to the advancement of material science, new options such as fiberglass and synthetic underlayment are becoming the ideal choice because of their extreme durability and moisture resistance. You will typically see synthetic underlayment in snowy and rainy states.

Roof Valley

The roof valley acts as a pathway where water can run off instead of collecting. It forms a v-shape intersection, and you can find it angled between two sloping roofs. The two pitched/sloped roofs form a 90° angle that functions as an internal gutter that forces water and debris to fall to the external gutter. It is essential to find the right installation type for a roof valley because if it fails, your house will have a severe leaking problem.


Amongst the crucial parts of your overall roofing system is the flashing – a material that prevents water from infiltrating various roof openings. The flashing is typical of metal construction, like copper, aluminum, or galvanized steel. 

You can find the flashing at the most crucial parts of your roof the water can penetrate, such as chimneys, vents, valleys, skylights, and dormers. The easiest way to spot the flashing is to find the areas of your roof where the metal sheets are attached to look like a staircase.


An abutment is a junction where the wall meets the roof’s face. This part functions like flashing; it prevents water from entering the roof – but this time, between the roof covering and the wall. This area is prone to water infiltration, so many roofing contractors employ abutment flashing to ensure a water-tight finish.

Roof Edge

The parts in this section involve the ones attached to the end of the roof. These parts are necessary to complete your roofing project and are equally important as the others mentioned above. Most of the components discussed below are responsible for adding an extra layer of protection for the roof and keeping the elements out of it.


It is the part of the roof responsible for preventing water from trickling from the roof down to the wall. Also known as roof edges, eaves are the lower walls of the roof that run the house’s perimeter and overhang the wall’s face. 

They’re a classic part of the architecture and serve decorative and practical purposes. Eaves can protect the walls of your house and, at the same time, match the roof’s aesthetics.


Just like eaves, the function of a soffit can be both decorative and practical. Its primary purpose is to hide the rafters and ceiling joints and protect them from natural elements that can degrade them, like mold and moisture. 

By concealing the rafters and ceiling joints, the soffit helps promote material longevity and protects them from degradation. You will see a soffit if you straighten up a roof. 


Typically constructed out of a non-corrosive metal sheet, a fascia connects the exterior part of your roof to your house’s outer walls. It is often confused with soffit. The main difference between them is their orientation. 

The soffit is horizontal, and you can find it beneath the rafter tails. On the other hand, the fascia is vertical and “faces” the front of the house.


Often referred to as a rake, a gable is a triangular wall you can find beneath two sloping roofs. While not all roofs have gables, a gabled roof is exceptional for water drainage and snow accumulation. It’s not technically a part of the roof per se. Gabled roofs can have their gables either with overhangs or just plain flat.

Drip Edge

While many would argue about the necessity of drip edges, many roofers and manufacturers still promote using it. A drip edge hangs from the side of the roof. 

It’s a metal flashing that functions like a gutter wherein it redirects the flow of water to safeguard the wall’s underlying sections. A drip edge will prevent water from infiltrating your roof through hidden nooks and crannies.


The gutter is a must-have when it comes to roofing systems. It’s an external roofing fixture that serves as a water discharging system that transports water away from the house. A roofer needs to install the gutter so that the water will not fall directly on the house or around its grounds. 

The angle by which the roofer installs the gutter system is essential because, if incorrectly installed, the water falling around your grounds can weaken the house’s foundation and can even cause basement flooding (if you have one).


The downspout is a vertical pipe installed from the roof and works closely with the external gutter. As the gutter transports water away from the house, the downspout catches it instead of letting it spill around your vicinity. Downspouts are usually made from PVC pipes, but you can also use those made from galvanized steel if you prefer something more durable and long-lasting.


Commonly referred to as an eave return, this part of the roof offers a graceful transition for the eaves and fascia to the home’s gable ends. A cornice sticks out from the sidewalls and is located on the topmost part of the roof.

Frieze Board

The frieze board is your roof’s least noticed part, yet it plays a massive role in keeping your house intact. It’s a trim a roofer inserts between the soffit and the house’s siding. Roofers usually install frieze boards flat against the house, but they may install it at an angle if the home has a gable roof. The frieze board also serves a decorative purpose and comes in different makes, such as wood, aluminum, and fiber cement.

Ice & Water Protector

While not entirely a necessity, some states like Florida will require roofers to install a secondary water barrier (aka ice & water protector) in their roofing project. These protectors serve as barriers against ice dams and, in the case of Florida, wind-driven rains. Such barriers are self-adhered waterproofing materials, and you’ll typically find roofers installing them in sensitive areas of the roof, such as valleys and eaves.


Like your home, your roof needs ventilation too. Some of its parts can let the air go in and out, helping eliminate moisture and lower its temperatures considerably. The parts below can affect your home’s changing moisture and temperature levels.


Speaking of the attic, there’s a part of the roof assigned mainly to keep it ventilated. The vent’s primary purpose is to ensure that the attic is adequately ventilated. Its design makes such a task possible, with an air inlet placed on the roof’s edge and an exit pointed outwards. Some types of vents available for residential home roofing include gable, under eave, plumbing, turbine, and ridge vents.


If you’re thinking of transforming your attic into a room, then a dormer would be a great addition. The raised section of the roof protrudes vertically, allowing light and extra ventilation to the room. 

Roofers also call it the dormer window because it provides a place for the skylight. Aside from lighting and ventilation, a dormer can increase your house’s curbside appeal and significantly improve its overall aesthetics.


The chimney is arguably one of the most popular parts of the roof. It is a vertical channel that acts as ventilation where smoke and gasses from various house parts that burn fuel go (stove, boiler, fireplace, etc.). Since it protrudes vertically from the roof, roofers will install a chimney flashing to prevent water from entering the crevices along its base.


Roofing materials are, in essence, protection, but they need something to protect them too. The parts discussed below will protect your roof and house from the environment, mainly from the water, heat, snow, wind, and any other elements that nature might throw at you.


A hip is a part of a hipped roof categorized by the intersection between two roof planes. You will typically see hipped roofs in snowy and windy areas because the orientation of these roofs acts as a deterrent against ice and wind, which will fall off the slanted surface easily. 

A hip is much like a ridge, only in a diagonal orientation. And like a ridge, a hip needs a particular type of roof shingle known as a hip shingle.


A skylight serves both aesthetic and functional purposes. In terms of aesthetics, skylights let natural light into your home, creating lighting like the ones you’d see in the movies. In terms of functionality, skylights can help reduce your home’s energy costs. 

Most people confuse skylights with roof windows because they look alike, but did you know they’re different? While roof windows are accessible and can open and close, skylights are fixed.


Your house is your family’s safe haven, and it must be up to the task of protecting your loved ones. The roof is your home’s stalwart component, tasked mainly with protecting your home from nature’s unpredictability. Understanding each part of the roof based on its functions will help you maintain your roof to its operational capabilities.

If you think some parts of your roof have damage or need maintenance, feel free to call Century Roofing Specialists.

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Prepare your Roof for Hurricane Season!

With hurricane season coming up and the recent storms we have been experiencing, it would be best to have your home prepared for any possible incoming storms. Our team of licensed experts can inspect your roof and your home to be at it’s safest possible form.

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