The Structure of a Quality Roof Explained

What’s the secret to a truly durable and long-lasting roof? While most people think the answer is a durable material, the answer lies significantly deeper beneath the outdoor surface. One of the keys to a quality roof is what lies at its very core: a well-constructed and rigid structure. However, many people overlook their roof’s structure because it’s not normally exposed to the same amount of abuse as the surface material outside. However, if you don’t have a strong, well-kept structure underneath, or if that structure starts to sustain damage due to flaws in the roof surface, your entire roof could be in pretty serious trouble.

On this blog, we’ll discuss what a good roof structure looks like and what you need to know about it.

Styles of Framing

The interior structure of a roof is called its “framing,” and over the years framing has evolved to be able to handle more weight and complex shapes at greater heights and requiring less dependence on the rest of the house below. Today, most modern roofs can withstand a tremendous amount of weight without piling on immense loads of stress on the walls of the home below.

In the past, “cut” roof frames were common. These roofs were essentially slapped together by carpenters who “cut” the rafters on site during construction. This was fine for short distances and small homes, but larger homes that needed longer spans required greater support, and that meant more load-bearing walls throughout a home. Today, most homes which encourage open floorplans and maximized space use different styles of trussed roofs that can support more weight without needing as much support, thus rendering “cut” roofs to be more or less obsolete. However, many homes with these older styles still exist, and there’s a chance your home may have one.

A-Frame roofs are perhaps the most common nowadays. These roofs are so named because of their signature A shape, including two sloped sides known as rafters and one or more cross-beams known as “joists.” The joists are connected to the rafters with cross-beams known as “jacks.” Generally, these A-frame roofs use a combination of joist, jacks, and rafters are called an “A-frame” and several of these A-frames make up the support structure that the sheathing, underlayment, and shingles or tiles are installed onto.

A-frame roofs can come in all sorts of different shapes or sizes depending on what level of support you need and what extent of an attic you’re trying to create. For example, you can use an A-frame roof to create the support structure for a vaulted or cathedral ceiling, making for large open rooms with minimal space between ceiling and roof material. These ceilings will often use sloped joists connected together, but strategically place the jacks and support beams to still provide optimal support. These are known as “scissor” structures.

You can build space for a room in your attic into your roof’s structure by simply leaving an open space in the structure of your A-frames. Generally these attic rooms require much taller roofs with large planes, but the added square footage in your home could prove useful.

Finally Triple-Howe roofs are special support structures that are designed to span great distances—as long as 54 to 80 feet! While these designs aren’t really flexible enough to offer space for attic rooms, these structures can create long, sweeping planes for large homes. These are also found fairly commonly in commercial buildings and warehouse spaces that need to have wide-open floorplans and where support pillars aren’t necessarily a bad thing.

Important Terms to Know

There are several key structural terms that you need to know as a homeowner so you can understand what your roofing professional is talking to you about. Here are some of the most important ones:

  • Plane: A flat roof surface that is sloped to allow rain, dust, dirt, and debris to roll off your roof. Your roof is often composed of at the very least two planes, and often features many more.
  • Ridge: The high-point along the top of your roof where two planes meet along a single flat line.
  • Hip: A point where two planes along the sides of your roof meet creating an outward-facing corner. This allows rain and precipitation to run off along the planes on each side of the hip, but not along the hip itself. The opposite of these points are known as valleys.
  • Valleys: A point where two planes meet and create an inward-facing corner, allowing rain and precipitation to flow down into the valley and into your roof gutters. The opposite of these points are known as hips.
  • Eaves: The section of your roof that extends past the outer edge of your walls, often featuring vents for proper attic ventilation.

If your roof is in need of a replacement, talk to the experts at Lyons Roofing about building a new structure over your home! Call us today at (520) 447-2522 to request more information.