By Sam Wasson
Updated Oct 28, 2022
Your roof is one of the most important structures in your home. Roofs are the first line of defense against rain, hail, snow, and other elements. If any section begins to fail, it can compromise the surrounding structure, leading to serious damage. Without a basic understanding of your roof’s systems and all their parts, you won’t be able to identify the source of a potential problem. To prevent this, you’ll want to become acquainted with all the different parts of your roof. To help you get a better understanding of your roof and all its most important features, we’ve created this comprehensive guide.
While most people live under a roof every day, not everyone takes the time to appreciate just how important and complex these structures are. Residential roofs must withstand the constant erosion of rain, UV rays, and wind while standing up to the impacts of hail, tree branches, and other debris. Thankfully, roofs possess multiple layers of protection, insulation, and reinforcement to defend against this daily barrage of weather.
Shingles, or other coverings like metal sheets, are your roof’s outermost protective layer. This outer layer is only a single part of your roof’s protective system but one of the most important. Shingles are the first line of defense against the elements, requiring them to be waterproof, dent-proof, and long-lasting. If your shingles fail, water will quickly affect the lower structures, eventually seeping into your attic, leading to mold and pests. The most common roofing materials are fiberglass and asphalt shingles, but there are plenty of other options to choose from, including:
Different roof coverings will have their respective life spans, costs, benefits, and drawbacks. Slate roof shingles, for example, can last up to 150 years but are extremely heavy and expensive.
Battens, also called roofing lathes, straps, or strips, are thin strips of material used to attach the topmost layer of roofing (shingles, metal roofs, etc.) They’re typically assembled in a large grid and composed of wood, metal, or plastic. Not every home uses battens, and they’re not required under most building codes.
Right beneath the shingles (and occasional battens) is the underlayment. Typically made from felt paper or synthetic materials, underlayment is a waterproof layer that protects the decking from leaks or extremely bad weather.
Next in line under the underlayment is the roof decking, also called sheathing. These are wooden sheets, typically made from plywood or oriented strand board (OSB), and are nailed directly onto the frame of your roof (trusses, joists, etc.) These sheets of wood create a flat and stable surface for your shingles and underlayment while providing additional reinforcement in the event of high winds or other difficult weather.
The next most apparent roof structure is the chimney. The chimney is a straight, vertical shaft running through your roof to one or more fireplaces. Normally constructed from bricks, chimneys are the primary means of ventilation for your fireplace and, occasionally, other appliances like the furnace.
A chimney saddle, also known as a “roof cricket,” is a triangular ridge that sits alongside the chimney. A saddle’s purpose is to divert water, snow, and other debris away from the base of the chimney. Saddles always sit on the higher side of the roof facing the chimney and are typically covered with shingles or metal flashing.
Roof flashing is thin sheets of metal, typically galvanized steel, placed along critical roof areas to help divert water, snow, and other debris. You can typically see flashing at the bottom of roof valleys, along the bases of chimneys, at the edges of vents and skylights, and anywhere a vertical surface meets a roof’s slope.
An eave is the overhanging roof section extending beyond the home’s walls. Eaves contain fascia, soffits, drip edges, and gutters.
The fascia is a board that runs along the edge of the entire roof. Also called a “transition trim,” the fascia acts as a solid and stable surface for your gutters and drip edge. The fascia board attaches directly to your rafters, trusses, and soffit, providing a high-quality, finished appearance.
The soffit is the covering material that sits on the underside of an overhang and is attached directly to the soffit joist and fascia. Soffits are typically vented and composed of wood, vinyl, aluminum, or fiber cement. Alongside the fascia, soffits create a protective layer for the edges of your roof.
The frame is the skeleton of the roof upon which the shingles, underlayment, and decking sit. It holds your attic and includes rafters (or trusses), joists, beams, a ridge beam (or board), deflectors, and insulation.
Your roof’s frame can be built using one of two systems, rafters or trusses. While similar and often confused, these systems are two completely different structures.
Rafters, also known as stick framing, are a series of long, sturdy boards that extend at an angle from the edge of your roof (the eave) to the peak. Rafters are constructed on-site and are made of 2×10 or 2×12 beams connected at the top by a ridge beam (or ridge board). The sides of the rafters are connected to the walls and eaves of the home by joists.
Trusses fulfill the same function as rafters but are constructed differently. Instead of using single large, heavy boards coming together at a peak, trusses are an interconnected web of smaller, lightweight boards that evenly distribute weight. Trusses are constructed at a factory and later delivered to the job site.
Roof beams are large, load-bearing wooden members of your roof frame. They’re typically the thickest part of your roof frame and run its entire length, providing structural support for the joists, trusses, battens, etc. Beams are often wood but can also be constructed from concrete or metal.
Joists are structural members that run horizontally between or on top of beams. Joists are positioned parallel to one another with even spacing to help transfer weight into the vertical structures (like posts or walls). Joists can either be concealed or visible and are typically made out of wood but can be made from metal or concrete. Joists can support specific roof structures, like eaves or dormer windows for sloped roofs.
A ridge beam, or ridge board, is the central load-bearing structure at the top of a rafter system. Depending on the slope of the roof and the required load your rafter system has to bear, you may have a ridge beam or a ridge board.
Deflectors are cardboard or polystyrene inserts that sit between rafters, allowing for better airflow over insulation.
Insulation is a material designed to help your attic and roof maintain a constant and even temperature. There are many kinds of different insulation materials and systems, including:
Most roofs have one or multiple vents that help regulate heat or remove harmful gases from the house. Some attics have vents on the sides of the attic walls, but these are less common and typically found in older homes.
This vent is where the fan from your kitchen lets out and resembles a small, curved black or silver box on top of the roof. These vents are grated and can sometimes be seen on walls.
Furnaces produce toxic or combustible gases that must be removed safely from the house. The furnace vent fulfills this purpose and is one of the most important vents on your roof. These vents are normally tall pipes with a round filter and cap on the top. A professional should inspect these vents once per year to ensure functionality.
Plumbing vents remove foul odors, harmful gases (like methane), and steam from the bathroom. They’re essential for the functionality of bathrooms, as they keep our water closets free of mold and dangerous fumes.
Attics need constant airflow to help regulate temperatures and prevent mold and mildew buildup. Attic roof vents can either be passive (such as a ridge vent), mechanical (powered), or use a turbine. Without one of these vents, the attic will grow mold and produce ice dams in the winter, which can lead to damaged or destroyed gutters.
The ridge is the peak of the roof where the two sloping sides meet and may be accompanied by an attic vent.
Valleys are the corners where sloping sides meet. These may be equipped with flashing. Valleys help divert water flow into gutter systems.
The drip edge is a small strip of metal flashing that attaches to the edge of the roof and directs the flow of water away from the fascia and underlayment.
Your gutters are one of your home’s most important systems. Gutters direct the water runoff and debris (like leaves, branches, etc.) away from your roof and foundation. As the water comes down from the valleys, the gutters direct the flow to downspouts, then further out to your lawn. This system keeps water from soaking into your walls and attic, preventing water damage and mold growth. You should clean your gutters twice per year, once during the end of summer and again at the end of fall.
Understanding your roof system’s parts is essential in identifying any possible problems. From simple leaks to full-on gutter collapses, if you don’t know the makeup of your roof, you won’t be able to diagnose the problem effectively. Hopefully, this guide will help you better understand all the important parts of your home’s most vital system. While most minor roof repairs can be done at home, we always recommend booking a professional inspection with a roofing contractor in case of serious damage.
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