Getting to know your roof

By Emma Peterson. 

Curious about the roof over your head? Keep reading to learn about roofing basics!  

For many homeowners, they will only deal with a reroofing project once or twice in their lifetimes. Because of this, many homeowners don’t know much about their roof and what roof care entails. This lack of knowledge can make those few occasions where homeowners must find a roofing contractor and choose a new roof overwhelming. 

Here at AskARoofer, we want to make this process less mysterious and more accessible for homeowners. In this article, we’ll cover some of the basics about your roof – like how to identify what type of roof you have and how to talk about it in roofers’ terms!  

What types of roofs are out there 

At the broadest level, there are two types of roofs – steep-slope and low-slope. The difference between these two types is pretty much what it sounds like – the angle at which the roof slopes. If the slope has a ratio of above 3:12, it is considered steep-slope. If the ratio is below 3:12, you have a low-slope roof. 

How do you calculate this ratio? Roofing uses the same "rise over run" idea that you learned in school. Rise refers to the vertical height of the roof and run refers to the measurement from the outside of the eave to the point below the center of the ridge. These two measurements are expressed as inches per foot and written in a ratio format – like 3:12.  

In general, you’ll find low-slope roofs (ratios below 3:12) on commercial buildings, such as a warehouse or office building, and steep-slope roofs (ratios above 3:12) on residential structures like homes or apartments.  

Steep- and low- slope are just the start of how you can categorize roofs. The next big differentiator that we want to highlight is material. Here are some common materials you might find on your roof:  

• Asphalt shingles: Shingles, specifically asphalt shingles, are the most common roofing material for steep-slope homes in the U.S. This is because of the material’s affordability and easy installation process. Generally, asphalt shingle roofs last around 20 years with proper maintenance. 
• Metal: While metal has a more expensive up-front cost than asphalt, metal roofing is growing in popularity for its incredible durability, and with proper maintenance, metal roofs can last from 40-60 years. Further, they perform well against storms, are more environmentally friendly and can be paired with reflective coatings to make structures more energy efficient.  
• Tiles: Tiles come in many shapes and forms. They can be flat, curved, interlocked or fluted and made of everything from molded concrete to slate and fired clay. In general, tiles are heavier and harder to install, but they add unmatched character to a home and can last up to 40 years or more. 
• Wood: Most commonly sold in the form of shake shingles, wood as a roofing material usually lasts 20 to 30 years. They do require a lot of maintenance to prevent issues like algae/moss growth and insect infiltration, but they are a solid choice for people wanting a natural aesthetic. 
• Membranes: Membranes are used on low-slope roofs and come in many forms, from PVC and single-ply to TPO and torch-down. In general, these roofing materials come in large sheets that install quickly, making them popular. They tend to last 15-20 years.  
• Coatings: Another type of roofing material commonly used on low-slope buildings, there are a few types of coatings, including acrylic, silicone, polyurethane and EPDM. Each material has its own benefits, but overall, coatings are prized for their easy application and ability to be restored at the end of their lifetime rather than fully replaced.  

The parts of the roof  

Now that you have an idea of how to broadly talk about your roof, we wanted to touch on the terminology for parts of your roof and what you might hear roofers talk about. Here are some general definitions for common parts of your roof:  

1. Decking: Sometimes referred to as substrate or sheathing, decking refers to the panels or planking that are placed between the insulation of your building and the roof system. In other words, it is the base that roofing products are attached to.  
2. Felt or underlayment: Felt or underlayment is installed between the decking and the final product (such as an asphalt shingle or metal roof panel). Its role is to protect the decking and building’s structure from moisture. 
3. Dormer: A dormer is a small, raised piece of roofing that projects out of the slope of a steep-slope roof. Usually features a framed window unit.  
4. Eave: The horizontal part of your roof that hangs over the side of the building. 
5. Drip edge: A piece of trim metal that is installed along the eaves of your roof and beneath the installed roofing product that ensures water runs-off correctly. Not visible from the ground. 
6. Fascia: Vertical rim, usually wood on residential homes, that is connected to the ends of the rafters and trusses. It’s the board you see where a gutter attaches to a roof.  
7. Soffit: The finished underside of the eave. When you stand under a roof’s overhang and look up, you are looking at the soffit. 
8. Penetration: Any constructed element that goes through the roofing. Think vents for fans, skylights, chimneys, etc. 
9. Flashing: Metal that is installed along intersections on your roof and around penetrations to keep water from seeping through joins in the roofing product.  
10. Ridge: When two slopes of a roof come together in a mountain shape, that uppermost, horizontal external angle is called the ridge.  
11. Valley: When two slopes of a roof come together in a “V” shape, they are called a roof valley.  
12. Vent: The outlets for air that are designed into your roof to let warm and/or moist air out. Can be found commonly along the roof ridge, gable or soffit. 

Learn more roofing terms at www.askaroofer.com/roofing-terms.  

Want to keep learning about your roof? Explore the articles and podcasts on AskARoofer.com. Got a specific question? Send it to our roofing experts!