Did you know that your roof is more than just the shingles on it? In order for your roof to do its job correctly—that is, keeping the internal space safe from water and weather—it needs to be a complete and effective system. Where you live, as well as the slope of the roof, will affect your roofing needs. Whether you are purchasing roofing for residential or commercial application, too, will influence your choices.
Regardless of the roofing system that is on your house, all roofing requires routine inspections and maintenance. If you want to keep your roof in shape, you need to know what to look for and when to repair and replace various elements of the roofing system.
The first step, though, is recognizing various kinds of roofing systems. Let’s get started.
Low-Slope Roofing Systems
Low-slope roofing may also be called “flat” roofing, but there are different kinds of flat roofing. Commonly commercial in application, you see flat roofing on factories, plants, and warehouses. However, there are some regions and architectural designs in which flat roofing is very common, such as multi-family units.
You will often hear low-slope roofing referred to as “membranes.” Most membranes have three main components:
- Weatherproofing layers
- Reinforcement to impede punctures and damage, as well as dimensional stability
- Surfaces for enhanced fire resistance, UV resistance, and improved hail and traffic resistance
Here are the four most common types of low-slope roof systems:
Otherwise known as “tar and gravel,” this roofing system is constructed using layers of asphalt or tar that alternate with supporting fabrics. On the final layer, stone or gravel is put down. When properly installed, a built-up roofing system will last around 40 years. It is seamless, waterproof, low maintenance, and also has excellent UV resistance.
Single-Ply Membrane Roofing
This is one of the most common low-slope roofing systems. Single-ply membranes are rubber (or other synthetic materials) that are fastened or adhered to insulation. You may see it referred to as EPDM roofing.
Spray Polyurethane Foam Roofing
An eco-friendly system for commercial, manufacturing, and industrial buildings. Spray polyurethane foam (SPF) is sprayed on as a liquid and then expands as a foam. When correctly maintained, it can last up to 50 years. It’s also seamless, waterproof, and energy efficient.
Asphalt Roll Roofing
This kind of roofing is made similar to a traditional shingle, but instead of squares of shingles, you get a roll. The rolls are installed by overlapping them. The downside to asphalt roll roofing is that it is not very durable or aesthetically pleasing.
The roofing system process begins with applying an underlayment, called the base sheet. From there, either with a torch to heat the tar or without, the asphalt roll is then unfurled over the underlayment.
Steep-Slope Roofing Systems
Seen more often than flat roofing are steep-slope roofs. These are roofs with sharp pitches, gables and valleys. Here are the main pieces to a steep-slope roofing system, aside from the covering layer:
- Roof deck – a structural substrate; usually composed of wood, such as oriented strand board (OSB) or plywood
- Roof covering – the external material to shed off water and ice; shingles and other materials
- Underlayment – temporary protection until roof coverings are installed. Later provides secondary weatherproofing. Sometimes called “paper” or “felt.”
Let’s now have a look at the general categories of roofing materials:
The most commonly used roofing covering in the US, asphalt shingles are squares of fiberglass, felt, mineral granules, and asphalt all sandwiched together. These shingles can be installed on a roof that has a slope of at least 4 inches.
3-tab shingles can last up to 20 years. Standard asphalt shingles come in a wide range of colors and require minimal maintenance. In order to properly install asphalt shingle roofing system, the shingles are applied over an underlayment, which covers a wooden decking. Most shingle manufacturers have their own version of the asphalt shingle roofing system.
Laminated Asphalt Shingles
Using the same roofing system as asphalt shingles are the laminated version. Sometimes, manufacturers call these “architectural” or “dimensional” shingles. The main difference is that laminated shingles contain two layers and are thicker than standard shingles. Because of these two layers, architectural shingles are more expensive and heavier than 3-tab shingles. You also benefit from longer warranties and better protection.
Slate roofing has been known to last for over 100 years. Some historical buildings in Europe still have their original slate roofing centuries later! Of course, being that slate is natural stone, it requires a specialized roofing system. In Europe, slate is applied without any roof decking. Instead, underlayment is placed beneath roof joists. Battens, which are horizontal boards, are then attached to the joists. From there, the slate is attached. In the US, slate is installed over roof decking but without battens.
Concrete and Clay Tile
The installation of a concrete or clay tile system is similar to a slate roofing system—you can go with or without battens. Rounded tiles are attached with mortar, nails or screws, wire, or adhesive. Tiles are placed over roof decking and underlayment.
Metal roofing systems are also called “standing seam roofing,” and it using preformed strips created by specialized machinery. It’s called “standing seam,” for the way the strips are overlapped, preventing water for getting in. Like any other roofing system, metal roof covering needs roof decking and underlayment. Some metal roofing also comes available as shingles.
Another natural option is cedar shingles, also called shakes. These wooden shingles are naturally rot and weather resistant. While they are expensive and high maintenance, they are very attractive. Also, unlike other options, cedar shingles are not fire resistant.
Typically, cedar shakes are installed with both roof decking and underlayment. However, the shakes or shingles become interwoven into the roofing felt. Shakes can also been installed similar to slate tiles, using joists and battens.
There are all kinds of roofing systems available out there, but not all of them are going to be right for your roof. Depending on the slop of your roof and the construction of the roofing system, one covering might be better for your home or business than another. By knowing the differences, you can discuss your options more easily with a professional roofing contractor and make the correct choice for your next roof.
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