Roofs go beyond layers of metal or asphalt shingles. Knowing how roofs work is important. It is because it helps you understand why you should invest in a proper rooftop. It is also necessary for your comfort and protection against the elements.

We want to help you understand the key roof components. So we have laid out the basic roof anatomy for you.

We will be discussing all that in this in-depth article. Let’s have a detailed look.

But first:


How Do Roofs Work?

Roofing goes beyond just a few shingles. It starts with rafters and a combination of protection layers preventing water and wind damage. Above the rafters is plywood, followed by shearing, a material that protects the home from moisture. Other layers of shingles go on top of the sheathing. Every single layer protects your home.

Why Is Investing In Building a Roof Important for Comfort and Protection Against The Elements?

A low-quality roof can lead to several problems. It includes leaks and damage from elements, which can sometimes affect the structure. All these problems can cause discomfort. A high-quality roof will protect your home and keep it in good condition for years. As a result, you should try to invest in high-quality roofing for your house or property.

What Is the Anatomy of Residential Roofs?

Roofs are more than shingles or rafters. A lot goes into the roofing, which constitutes their anatomy. The Anatomy of Residential Roofs includes:

  • Truss: Serves as the roof’s skeleton
  • Deck: serves as a system for attachment
  • Underlayment: primary waterproofing element
  • Deck- Armor: Allows evaporation of moisture
  • Drip edge: Prevents water build-up
  • Flashing: Protects against water intrusion
  • Outer roofing
  • Attic ventilation
  • Ridge cap shingles
  • Soffit and Fascia

What Role Does Truss Play On the Roof?

The truss is the main skeleton of the roof. It determines the slope of the roof. The truss often determines what other materials you can install on your roof cover. Rafters are also a part of the truss, and decking materials are nailed to these wood lengths.

How Strong Does a Truss Need to Be?

The strength of a truss requires a formula: M+3= 2*N, meaning that the members of a truss with an addition of 3 must equal twice the number of nodes. 

If both sides of the equation are equal, it means roof stability and the ability to handle stress. If unequal, the truss is not strong enough, and the builder must add more nodes to achieve strong support.

Common Roof Slopes

The most common roof Slopes are conventional roof slopes for residential roofs. Traditional slopes have a pitch between 4/12 and 9/12 on most homes. 

Steep roof slopes are also common, with a pitch exceeding 9/12 of conventional roof slopes. Steep roof slopes have other benefits, but their main point of attraction is their beauty.

What Kind of Materials Can I Install on My Roof?

For roofing installation, there are several materials that you can use. However, these nine materials are the most common:

  • Wood shingles
  • Asphalt shingles
  • Solar tile
  • Metal roofing
  • Stone-coated steel
  • Slate
  • Rubber slate
  • Clay and concrete tiles
  • Green roofs

How Are Rafters a Part of Truss?

Rafters and trusses both support the roof. They ensure that the roof has enough strength to carry weight. Both of them are triangular in shape, although trusses have more triangle webs inside the main frame. Without rafters, the trusses will not be able to provide the strength that the roof needs. The sloping outer beams of rafters also support the roof cover.

What Is Decking and What Is Its Purpose?

Decking is also known as wood sheathing. The flat surface provides an area of attachment for the rest of the roofing system. Plywood, oriental strand board, or similar materials are nailed to the rafters. When there is a replacement roofing, the builders strip the old roofing up to the decking.

What Are the Different Types of Decks

There are several types of decks, just like home foundations. Having a deck with proper installation is vital for your home if you want to keep the rain, snow, and wind from causing any damage. The three types of the roof deck to consider when building are:

  • Oriented strand board
  • Concrete
  • Plywood

These are suitable decking for either building, remodeling, or repairing your new or used home.

What is Wood Sheathing?

Wood sheathing is a layer of boards or other wood fiber materials that a builder applies to studs, joists, and rafters. The application of a wood sheath strengthens the structure of a building. It also serves as a base for exterior waterproof cladding.

The wood sheathing is suitable for both residential and commercial construction. It provides higher insulation for the home and increases the stability of a building.

How Does Decking Relate to the Sheathing?

Most contractors use both terms interchangeably, but they are the same. Roof decking or sheathing is the wooden board that makes up the whole foundation of your roofing system. It serves as a resting place to install shingles and other roofing components. 

Roof decking or sheathing is one of the most critical pieces of roofing. Without it, the roof will have nothing to stand on, so there will be no structure.

What Is the Oriented Strand Board (OSB)?

Oriented Strand Board is the most common types of roof decks. Its makeup includes a bond of intertwining wood strands and a waterproof resin that provides resistance to water and moisture. It is less expensive than regular plywood.

One major problem with OSB is that the material is susceptible to trapping and storing moisture. If the roof has an area that allows water up to the deck, moisture can penetrate the space and cause rotting. This damage can lead to hefty repair costs for the homeowner.

Why Is Plywood or Similar Materials Nailed to the Rafters?

Rafters are load-bearing structural members necessary for roof construction. They run from the hip of the roof at a sloping angle to the roof wall plate, roof beams, or columns, depending on the roof support structure.

It means that rafters receive the load from other roof coverings. By implication, different roofing materials are nailed to the rafters to transfer the load or weight appropriately.

Why Is the Old Roofing Stripped Up to the Decking During Replacement

In most cases, the builder must remove your existing roofing materials before laying the new roof. Your old tiles, metal paneling, and shingles will be removed, leaving the deck exposed. 

Stripping the old roofing up to the deck allows contractors to inspect the roof’s condition and underlayment. When the roof deck shows any rot or decay signs, you must rebuild it. A professional contractor will ensure that they get rid of the old roofing materials and take them safely away from your property.

What is Underlayment?

Underlayment is what lies between the roof deck and the shingles. It is either plywood or OSB. Instal the underlayment directly on the roof deck, providing a secondary layer of protection from the elements. For instance, snow, rain, and wind. 

There are two types of roofing underlayments. They are felt and synthetic underlayment. Each of these roofs has its pros and cons depending on the suggestion of the roofing contractor.

What is Roofing Underlayment Made Of?

Synthetic roofing underlayment is made of durable polymers that provide extra strength and longevity. This underlayment is resistant to moisture and offers good protection from the weather.

Felt roofing underlayment is made of fiberglass mats with asphalt or saturating paper.

What is Roofing Felt?

Roofing Felt remains one of the oldest types of roofing underlayment. Its makeup consists of saturating paper or fiberglass mat with asphalt.

Roofing felt is typically available in two types: No.15 felt and No. 30 felt. No. 30 felt is thicker, stronger, and less prone to tearing during installation or weather events. No. 15 felt is not as strong as No. 30 felt.

What Are the Different Manufacturers of Roofing Systems?

The different manufacturers of roofing systems include:

  • GAF materials corporation
  • Owens Corning
  • CertainTeed
  • Malarkey Roofing Products
  • Atlas Roofing
  • Tamko Building Products
  • IKO
  • PABCO Roofing Products
  • Firestone Building Products
  • Englert, Inc.

What is GAF?

GAF is an American manufacturing company. It is based in Parsippany, New Jersey, and has a history from the late 19th century. GAF is an acronym which stands for General Aniline & Film. The company has a history of primarily manufacturing roofing materials for residential and commercial uses. 

What Does GAF offer?

GAF offers high-quality roofing. There’s a probability that one out of every four roofing is GAF. It is because the roofing products they offer are top-notch. 

Although GAF confidently supports its roofing products with excellent warranty options, they also have exclusive access to roofing warranties such as The System Plus and The Golden Pledge. GAF also guarantees high-quality materials with efficiency and ease.

What Is Deck Armor?

Deck Armor is a premium, breathable underlayment that provides a tough and durable layer of protection under the roof’s asphalt shingles. The deck Armor protection is against elements such as rain pushed by wind and other sources of moisture that can damage your roof. The deck armor allows inside humidity to escape the roof system and helps to prevent premature deterioration of a roof system.

What is a Drip Edge?

A drip edge is a metal flashing. Installation of a drip edge is usually at the edges of the roof. The purpose is to help control water flow away from the fascia and protect the underlying roofing components. A drip edge hangs over the sides of a roofing system and has a small metal flange that bends away from the fascia. 

It does not corrodes or stain, making the roof look good and stable.

How Does Drip Edge Prevent Rain Water Build Up?

A drip edge prevents the build-up of rainwater by dripping water. It needs to be correctly installed. If a drip edge is not installed correctly, the rainwater that falls on the drip edge will roll off. It will then go behind the roof’s fascia boards and cause a mess in the exterior siding of your house.

How Does It Help Guide Into the Gutter?

Gutter placement is under or behind the drip edge of your roof. A drip edge hangs over the rooftop and has a lower edge that projects outwards. The water that falls into the drip edge follows capillary action and drips right into the gutter. 

The drip edge and the gutter work together with the goal to control the direction of the drilling water. But if the dripping border is not good, it can damage the gutter system.

What is Flashing?

Flashing is a flat thin piece of metal that helps waterproof the perimeter of roofing systems. It helps to send water away from the joints, preventing it from entering the cracks in a roof.

Flashing works by collecting pooling water and directing it away from the location.

Flashing helps to maintain a watertight roof. Without a roof flashing, rainwater would run down the rooftop and enter the house’s interior, especially in homes where the chimney rises through the roof.

Why Install Flashing on Chimneys, Vents, and Dormers?

Flashing is vital for vents, chimneys, and dormers. It helps to keep roof components waterproof and prevent roof damage. If there is no flashing, roof components such as the junctions can come into contact with water. The resultant effect is saturation, leaks, and damage to the house’s element or structure.

How Does Flashing Protect Vulnerable Areas Against Water Intrusion?

Flashing protects vulnerable areas from water intrusion by preventing breaks in the roofing plane. It is a barrier in areas where the roof appears susceptible to water intrusion, especially where caulking may be insufficient or is not a suitable solution.

What Is Outer Roofing?

Outer roofing is the topmost covering of a building. It includes all materials and construction that are important for support in the walls of a building. It protects against sunlight, wind, snow, rain, and other extreme temperatures. The outer roofing is an integral part of any building.

What is the Main Roofing Material?

There are several roofing materials, but asphalt composite shingles are the primary roofing materials. It consists of a fiberglass base with toppings of asphalt and mineral granules. These shingles are a good choice and serve most home roofing needs. They are lightweight but also durable and do not wear quickly.

How Does Installation Begin in the Case of Asphalt Shingles?

Roofers will start installing the first layer by installing a marine grade ply above the rafters. It is vital to use marine-grade plywood for durability, and the general use of ply does not always last long. Sarking is the next phase as it ensures waterproof protection. After these, install the powder coat aluminum drip edge.

What Do They Call the First Row? What Materials Do They Use?

The first row of asphalt shingles is the first part that a roofer lays. The type of materials they use varies for the type of asphalt shingles roofers purchase. For starters, roofing contractors may begin with a shingle roll. This is a raw material the roofer cuts to the length of the roof. 

Alternatively, a roofer can use a starting row of full-sized shingles. This is possible if the roofer turns them with the tabs pointing upwards.

What Does GAF Offer As Starter Strip Shingles?

Generally, GAF starter strip shingles include a high-quality adhesive. The adhesive is well fitted and will lock the shingles tight, keeping them in place. It helps to prevent shingle blow-off too. Individually, GAF offers four starter shingle products:

  • The GAF starter match
  • The GAF quick start
  • The GAF weather block
  • The GAF pro start

Why Do They Install Standing Seam Metal Roofs Vertically?

Roofers install standing seam metal roofs vertically because it is more durable. It is also resistant to water damage and will not allow the roof siding to trap water. 

Vertical installation also makes maintenance easier. It is easy to clean and does not require much work.

What is Attic Ventilation?

Attic ventilation is a form of ventilation that allows air in and out of the attic. Roofs face the sun. As a result, they build up considerable heat during warm seasons. Attic ventilation helps to provide an outlet for the gain of heat. It then allows fresh air to flow into the attic and balance the inner temperature.

Why Do They Leave Gaps At the Peaks?

Roofers leave gaps at roof peaks so that heat can escape and vent. There should always be at least a gap of about one inch between siding materials and lower roof planes. It helps to prevent the intrusion of moisture behind the siding material. Majorly, houses with wood, composite, and vinyl materials are built in this manner.

How Does Trapped Heat Lead To Ice Dams?

Some homes lack sufficient insulation. As a result, the attics have no proper heat loss or poor ventilation. Sometimes, a combination of these two factors occurs. As a result, ice ridges begin forming on a roof’s edges, referred to as ice dams.

How Do Gaps Cover Strips of Hollow Material?

A filler strip goes under a sheet, while an opposite strip goes over the same sheet. All filler strips bond to the valley of the sheeting with a flexible waterproof sealant to create bonding. This bonding adds an extra layer of protection when filling gaps in roof sheets. It helps ensure that the gaps cover the strips of the hollow material and that nothing gets through them.

How Effectively Do These Gaps Allow Heat to Escape?

When a roofer leaves gaps in the installation, air can move easily around the foil. It means that ventilation can take place well. The hot air present in the building will travel through the path of the weakest resistance to leave the building. A roofer should install foil with the proper air gaps, and it allows maximum ventilation and the benefit of full coverage.

What Are Ridge Cap Shingles?

Ridge cap shingles constitute the same materials as standard shingles. It is mainly because both types are asphalt shingles. The difference between them is that ridge cap shingles are thicker and pre-bent. As a result, they can fit along the ridge easily. They are also smaller than other regular shingles.

Why Must They Cover the Peaks for a Consistent Look?

Ridge caps are the most recognizable parts of a roofing system. As a result, they must cover the peaks for a consistent look. It is because they are at the roof’s highest point and usually run in opposite directions. As a result, they have a vast impact on the outlook of a roof. Not covering the peaks will affect the consistency and stylistic design.

How Do Modern Asphalt Shingle Roof Systems Feature Specifically Manufactured Ridge Cap Shingles?

Modern Asphalt Shingles can be wrapped above the ridge line to create protection. Another layer of shingles then covers it to make a cohesive appearance. In the process, a ridge line can occur under the building. To fix this, the roofer sets a ridge cap over the space to shield it. It prevents snow, rain, ice, and pests from sneaking into the home through the roof.

What Is the Soffit?

A soffit is an interior or exterior architectural feature. It is generally the aloft horizontal underside of any construction roofing. Its archetypal form, which sometimes incorporates or implies the projection of beams, is the underside of the eaves.

What Is Fascia?

The fascia is also known as fascia boards. They are horizontal panels wound around the edge of the roof of a building. Fascia boards usually overhang the walls of the building. As a result, it closes the gap that is pretty between the walls and the roof.

What Does the Fascia Protect and How?

A fascia board protects the entire roof line. It secures the mounting surface of the gutter. Fascias are horizontal and robust and cover the roof rafters with exposed trusses connecting the rooftop with the walls.

What Does the Soffit Cover?

The soffit covers the underside of eaves and porch ceilings, providing protection. It can also provide a system for hidden vents. Soffit is comparable to vertical sliding, and its installation goes beyond that of actual panels.

Why is There a Gap Between the Fascia and the Siding?

The build-up of moisture can sometimes occur on the roof. It affects the insulation of the home and can lead to long-term damage. There is a gap between the fascia and the siding. The moisture intrusion can be prevented behind the siding material. Generally, roofers recommend a one-inch gap between siding and other roofing materials.

How Does Soffit Allow Attic Airflow?

The soffit allows fresh air to get inside the attic space. This gust of air gets through the process of convection or a power vent. The attic then expels hot air via roof or gable exhaust vents. The constant air flow creates good ventilation in the attic space.

What Are the Common Parts Of a Roof and Its Layers?

The common parts of a roof and its layers are:

  • Decking or sheathing
  • Roof edge
  • Attic
  • Saddle
  • Ridge
  • Valley
  • Underlay membrane
  • Eaves membrane
  • Roof vents
  • Drip edge
  • Reflectors
  • Plumbing vent
  • Flashing
  • Shingles

The best way to familiarize yourself with roof parts is to read and understand them. You can ask a builder, roofer, or contractor if any roofing terms seem vague. There are also several online courses and even YouTube videos that teach about roof parts.

Parts of a Roof


The decking usually consists of half an inch of plywood. It provides covering and reinforcement for the roof structure and a nail bed or foundation for the shingles. Decking is also known as sheathing.

Roof edge

Also known as eaves edge or fascia, a roof edge comprises the boards that run along the edge of the roof or eaves. 


An attic is a space under a roof. It requires enough ventilation. It is so that it can protect the roofing system against excessive heat and warm or moist air.


The saddle is usually behind the higher side of the chimney or behind similar roof projections. It helps to divert rainwater around the chimney and the roof.

The Ridge

The ridge is the horizontal line at the roof’s top. It allows air to flow into the attic and prevents roof leaks. 


A valley is the V – Cut angle that lies at the junction of two slopes of a roof. A roof valley’s primary function is to allow the proper flow of water from the rooftop.

Underlay Membrane

The Underlay membrane consists of asphalt or other synthetic fabric. It protects the shingles against resin that occurs as a result of wood decking. It also protects the decking against bad weather.

Eaves Membrane

It is a protective membrane that passes under all or some of the asphalt shingles. It prevents the infiltration of water that occurs as a result of ice dams in winter.

Drip Edge

A drip edge is molding. It covers the edge of the roof and reduces the risk of water infiltration.

Roof Vents

A roof vent is an enclosed structure with metal or plastic openings and fins. It ensures that the space in the attic is well-ventilated. The most effective vents have four sides that allow proper capturing of wind from all directions. The result is a suction effect.


A deflector is a piece of polystyrene or cardboard that the roofer inserts between two rafters. It helps ensure an unlimited airflow over the insulation besides the soffits. Roofers and roofing experts advise a space of at least two inches under the decking.

Plumbing vent

A plumbing vent is a pipe that emerges from the roof and allows air into the plumbing system. It will enable the proper flow of wastewater to the sewer or leaching field of the septic system.


Also known as joint covers, flashing consists of galvanized steel, plastic, or aluminum. It can be flexible or rigid. It is a type of resistant molding that prevents water flow near the roof openings. Flashing is vital for valleys and the bases of chimneys, roof vents, walls, and plumbing vents.


Shingles constitute fiberglass and asphalt. They protect the roof from rain and other elements.

Roof Plane

A roof plane is the surface of the roof. It is flat but pitched, usually at an angle. It is also known as the field of the rooftop. A typical roof usually has two roof planes. The two roof planes on a roof can have different slight-degree inclinations.

Roof Peaks

There can be different peaks in a roof. While there are no unique materials, hip and ridge shingles undergo specific designs for this roof part.

Ridges are not the weakest points on the roof. It is instead the highest point where two components of the slope meet. Gamble roofs are the most common roof with ridges. A ridge or peak is vital because of the stability it provides.

Ridge Vent

A ridge vent is a type of vent that the roofer installs at the leak of a sloped roof. It allows the escape of warm, humid air from the attic of a building. 

A ridge vent runs horizontally along the roof’s peak to allow proper ventilation into the attic of a building.

Attic Ventilation

Most codes make use of the 1/300 for minor residential attic ventilation. It means that 1 square foot of ventilation is required for every 300 square feet of enclosed attic space. It consists of half in the upper portion and half in the lower part.


Flashing constitutes thin pieces of material a roofer installs on a roof to prevent the passage of water into the house. It can be in any material, but most roofers and homeowners prefer metal because of its durability and flexibility. 

Flashing installation surrounds roof features such as vents, skylights, and chimneys. Water runs down the flashings to the shingles instead of the roof deck.

The Hip

The hip is the external angle where adjacent sloping sides of a roof meet. The primary purpose of a hip is to provide structural stability. 

A hip is different from a ridge such that a ridge refers to only the uppermost peak that occurs on a roof where two opposing slopes meet.

What are The Steps to Building a Sounding Solid Structural Deck Foundation for a Roof?

The processes include:

  • Define the function of your roof deck
  • Find the dimensions of your roof deck and develop a plan.
  • Choose appropriate and high-quality materials.
  • Follow all the regulations and permits for building a roof deck.

Roofing Underlayment

The main purpose of roofing underlayment is that prevents the formation of molds. It also prevents damage to your home that can occur as a result of leaks. 

The two types of underlayment are synthetic and felt. Synthetic underlayment is becoming a more popular material because it outperforms felt in water and mold resistance. It doesn’t absorb water like felt underlayment, so it protects the home more.

The major advantage of felt underlayment is the cost. Felt underlayment costs less than synthetic underlayment and is best for homeowners under a budget.

On the other hand, synthetic underlayment is hard and fast to install. It is also safer and repels water.

Laminated Architectural Shingles

Laminated architectural shingles are also known as architectural shingles or laminated architectural. They are a kind of asphalt shingle made of multiple materials and a more refined type of asphalt. 

Laminated architectural shingles are different from regular shingles. It is because they are made of more refined asphalt, a heavier base, and multiple layers of materials.

Manufacturers make architectural shingles by employing separate rolls of substrate materials. Each roll has a coating of asphalt composition and granule formation. It thereafter undergoes lamination, after which they are transversely cut out. 

Architectural Shingles are the opposite of three-tab shingles in that they provide a more dimensional look to the roof.

Roof Gable

A roof gable is a roof that consists of two sections where the upper horizontal edges meet to form a ridge. The roof gable is the most common roof cover in cold or temperate climates. Roof gables are sometimes called roof rakes because of the sloped sides of the gable roof.

What Is a Metal Drip Edge?

A metal drip edge is a metal flashing that a roofer installs at the edges of a roof to help the flow of water. It directs water away from the fascia and protects the rooftop.

The relationship between metal drip edge, rake, and eave are crucial. Installation of a metal drip edge should be on the eaves and rake of a roof. Install the drip edge on the deck on eaves; on rakes, it is directly over the drip.

What Is a Dormer?

A dormer is like a small room. It has a window that projects out vertically from the rest of a sloped roof. A dormer allows cross ventilation, adds architectural style, and brings natural light. 

Common elements of a dormer include the rake, fascia, lookout, and ridge board.

Ice and Water Barrier

An ice and water barrier is a waterproof underlayment. It protects the vulnerable areas on a roof from ice and water damage. Ice and water barriers usually consist of polymer-modified bitumen. 

Roofing professionals install ice and water barriers on eaves, rake edges, valleys, and overhangs. It is because these areas are more vulnerable to ice and water damage.

What is an Eave?

An eave is the edge of a roof that overhangs the face of a wall. It usually projects beyond the side of a building. The heaves form an overhang, and the result is that they steer clear water from the walls. An eave may also be part of a decorative architectural Style. Roofers make waves by extending the rafter structure outside the house’s frame.

Types of Eave

The four major types of eaves are:

  • Exposed have
  • Soffits have
  • Boxed-in eave
  • Abbreviated eave

In an exposed eave, you can view the underside of the roof and supporting rafters from underneath.

The soffit eave adds a board that connects the bottom tip of the eave with the building’s side at 90°.

A boxed-in eave closes the roof rafter when you view it from below. 

An abbreviated eave is cut off and happens at the side perpendicular to the house.

What Is An Under-eave Vent

The under eave serves as an air intake roof vent. It helps to remove heat from the roof space. It also reduces the overall heat load on the building. 

Under eave vent extends past the warm wall line. It allows dry air into the attic by creating airflow. 

Roof layers include:

  • Underlayment
  • Ridge vent
  • Roof shingle
  • Asphalt shingle
  • Slate
  • Roof flashing

All of these have been thoroughly discussed in the above article.

In Essence

It is vital to understand your roofing system. It helps you become a more responsible homeowner and care for your roof better. You can also understand the necessary roof repair and upgrade terms. 

The article above is an in-depth description of everything you need to know about roofing. It is best to familiarize yourself with these roof terms if you decide to become a roofer, so you don’t despair if anything goes wrong.

Now that you’re familiar with the anatomy of a roof, you can start noticing your roof parts and their usefulness.