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More Than Just Shingles: Components of a Complete Roofing System

Getting a roof replaced is a huge deal for most homeowners. As one of the biggest home repair expenses, it is important to purchase a roofing company’s most recommended roofing system – one that is durable and reliable. Besides picking out a capable licensed roof repair company to handle the project, choosing a complete roofing system is the most important decision you can make to ensure a well-functioning, long-lasting roof on your home.

Homeowners often assume that shingles make up the entirety of a roof. The truth is, a complete roof system is made up of many more essential components that work together to ensure superior weather protection and lasting performance for your home.

Is your old roof failing? If so, you should consider having your entire roof replaced to help you make the most of your investment. Before you do so, it might help for you to understand what makes up your roof and the role each part plays in keeping your home protected.

Parts of a Roof

Summertime is often considered the best time to replace a roof, usually the third week of March until the third week of  September, when the sun’s heat is at its optimum and can help the shingles bond together better. Re-roofing in cold weather, on the other hand, is never a good idea as the cold reduces the effectiveness of the self-adhesive strips under the shingles. If you must re-roof at other times of year, it’s best you adjust your installation method (you can fortify your roofing installation by, for instance, adding glue dots under the shingles).

Contractors that offer residential and commercial roofing services share with us the different parts of your roof about which you may want to know more:

Roof deck/decking (or sheathing). Made of construction-grade plywood, usually 1⁄2-inch plywood, the roof deck forms the base layer of the roof itself. The decking is what reinforces the roof structure and provides a nail-bed for your shingles.

Roof edge (or eaves edge). Also called fascia, these are all the boards that run along the edge of the roof or eaves, overhang the face of a wall and, normally, project beyond the side of a building and throw water clear of the walls.

Leak barrier. A leak barrier makes it easier for you to keep rainwater away from your roof’s more vulnerable areas. Leak barriers are located along the roof’s edge, including gutters and eaves, and around the chimney and any other penetration through the roofline like skylights or vents. Leak barriers will help keep your home dry and damage-free.

Attic. This refers to space under your roof. It’s essential that you keep the attic well-ventilated to protect your roofing system against excessive heat in the summer and warm moist air generated by the house in winter.


Located behind the higher side of a chimney, this is a structure that’s meant to divert rainwater around it. It essentially prevents water from leaking where the roof meets a chimney.


This refers to the horizontal line at the top of the roof. The ridge of a roof is the peak, where two opposing roof planes meet; in more technical parlance, it’s the “highest point on a roof, represented by a horizontal line, where two roof areas intersect, running the length of the area.”


The “V-cut” angle is found along the junction of two slopes on a roof. A roof valley is very prone to leaks, especially if you have an older roof.

Underlay membrane

Made of a synthetic fabric, rubber membrane or felt saturated with asphalt, the underlayment helps protect the shingles against resin released by the wood decking; it also protects the decking itself against bad weather. Besides covering any exposed roof decking in your home, it helps prolong the lifespan of roof decking. Recent advancements offer greater durability and breathability.

Eaves membrane

A protective membrane that goes under the asphalt shingles to prevent water infiltration caused by “ice dams”. It’s a thin underlay that essentially prevents water from leaking into the home.

Drip edge

This is moulding that’s designed to cover the edge of the roof and reduce the risk of water infiltration. Also known as eave and drip flashing, these components are used on the overhang, at the sides or ends, and at the edge of the roof to protect the facade

Roof vents

Made of metal or plastic, these enclosed structures feature openings and fins to ensure that the attic space is properly ventilated. They typically have four open sides and rise above the roof to better capture the wind from all directions and produce a suction effect. To fully ventilate the attic, there must be an air inlet at the base of the roof that is made through perforations in the eaves’ soffit. These vents keeps excessive heat from building up in your attic to help prevent premature wear and tear on the roofing materials and to keep your home more thermally comfortable.

Starter strips

These are installed at the edges of your roofline to prevent wind and water penetration under the shingles. Starter strip shingles include a high-quality, properly positioned adhesive that will tightly lock your shingles in place to help prevent shingle blow-off.


Polystyrene is inserted between two rafters to ensure the free flow of air over the insulation near the soffits. At least two inches of space should be under the decking.

Plumbing vent

Emerging from the roof, this vent admits air into the plumbing system to allow wastewater to flow properly to the sewer.


Flashing is a type of resistant moulding that prevents the water flowing near roof openings from leaking through your roof. Made of galvanized steel, aluminum or plastic, it is found in valleys and at the bases of chimneys, walls, roof vents and plumbing vents.


Shingles are highly visible components that come in a variety of materials, colors, textures and thicknesses that add greatly to your curb appeal, effectively protect your home from the elements and lend a house character.

Shingle cap

This covers the roof’s peak and enhances the look of the system.

Choosing Your Shingles

Asphalt shingles are a huge favorite of American homeowners because they’re affordable and easy to install. Their waterproofing function works by gravity: as long as water is flowing downward, nothing will penetrate. The lifespan of most fiberglass-based asphalt shingles is between 20 and 40 years.

While you could opt to install new shingles over old ones, doing so is not recommended as underlying defects will eventually distort the new covering. Thicker and heavier shingles are more resistant to inclement weather. Three-tab shingles have a single reinforcement layer; those with two or three reinforcement layers are called laminated (or architectural) shingles. The latter is  more expensive, but lasts longer.


Problems, such as decking in poor condition or deficient attic ventilation, can void a warranty. Before installing your shingles, therefore, take all necessary corrective actions recommended by your contractor.

With all the right components that make up a complete roof, you can ensure decades of exceptional protection and performance. Trust a GAF Master Elite® roofing contractor like Orion Home Improvements to expertly install this system on your home.


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