Think the roof over your head is just shingles? Beneath the visible shingles are essential components such as the roof deck, underlayment, cements and sealants. These layers help the roof stand up to the long-term harsh effects of sun, rain, ice and other conditions, extending the life and beauty of your home.
Starting at the bottom layer, TAMKO Building Products, a leading manufacturer of residential roofing, offers the following primer on the makeup of a typical residential roof.
Roof deck: The critical foundation
The roof deck is the base layer for the other components. These flat structural panels offer crucial support. Commonly made of sheets of plywood or oriented strand boards (OSB), these 4-foot by 8-foot panels nailed directly to a home's roof trusses or rafters act as the structural backbone of the roof deck. The type of shingles selected determines which roof deck material will be most appropriate.
Underlayment: The essential moisture barrier
Underlayment is a thin, water-resistant barrier protecting the roof deck and home from moisture. Underlayment commonly comes in wide rolls and is installed in long, overlapping horizontal rows across the roof from bottom to top, on the deck before shingles are installed. This keeps moisture away from the roof deck during construction and is a second line of defense beneath shingles.
Shingles: More than an attractive cap
While shingles can be the topper to a home's appearance, they also serve a critical role. Shingles are designed to efficiently shed rain and moisture from the roof, protecting the layers beneath. All shingle types employ an overlapping installation pattern to keep moisture from getting past the surface and ensure that water is shed efficiently to the ground.
Asphalt: The most affordable type of roofing material, asphalt shingles are found atop most single- and multi-family homes. Architectural shingles have more layers than the single-layer 3-tab design and often have a longer manufacturer warranty because they provide more protection.
Metal: Typically made from steel or aluminum, these can be long, overlapping, interlocking vertical ridges running from top to bottom and fastened with special screws and washers or die cut shingles that interlock and are applied like an asphalt shingle. Metal roofs provide enhanced protection from the elements, a long service life and can mimic the look of slate, tile or wood shake.
Tile: One of the oldest roofing materials, tile roofs are made of clay or concrete formed into a wide variety of overlapping shapes. Tile remains popular in the American Southwest as it endures high heat and sun exposure. Tile roofs can last a long time with low maintenance costs but are expensive to install.
Slate: Made from natural slate or stone, these classic shingles are cut to shape and held into place with pegs. Slate is long-lasting if maintained properly but expensive to install and vulnerable to peg failure and slate breakage.
Wood: Wood shingles or "shakes" are thin, tapered strips of weather-resistant wood. They have a rustic look and are commonly made from western red cedar, cypress, pine or redwood.
Composite: This modern, engineered shingle is made to resemble wood shakes, slate and tile. Composite shingles are attractive, low-maintenance, long-lasting alternatives to the real thing.
Starter shingles along the perimeter of the roof surface are often required when installing shingles. These serve to waterproof the eave and rake edges and, with the application of adhesive, provide an anchor to prevent shingles from blowing off in windy conditions.
Ventilation: How a roof breathes
Proper roof ventilation permits a consistent flow of air, encouraging cooler air to enter the house and warmer air to exit. This aeration creates a more consistent temperature throughout the roof, providing cooler in-home temperature in summer and preventing ice damming in winter. Consistent temperature also minimizes moisture buildup inside the home. Proper ventilation is critical to preserving roofing components.
A local professional roofing contractor can determine which attic ventilation is appropriate for a given home or climate.
Hip and ridge shingles: The crown
Hip and ridge shingles cover the peak of a home's roof, bridging the gap between the shingles installed on each side. This helps protect the roof's decking at the crown and control the efficient shedding of water. It can also cover unattractive vents installed on the ridge. A variety of styles of hip and ridge shingles are available, but each serves the same vital function.
Understanding the fundamentals of roofing can help any homeowner have a more meaningful conversation with a qualified roofing contractor when planning a roofing project or repair.