Homes or buildings with a steep slope roof have the opportunity to design a roofing system that is the showpiece of their property since it’s on full display. A low slope roof, on the other hand, does not have that same opportunity as the roof has low visibility, or even none, when looking at it from street level. However, that doesn’t mean the type of roof you choose for a low slope isn’t important.
Choosing the correct type of roof system for a low slope is crucial to avoiding water damage to your home. While asphalt shingles, the most common type of roof, is not a good fit for a low slope, there are certain types of roofing systems that are exceptionally well suited for low slope applications.
At Western States Metal Roofing, we have been in the roofing industry for over 20 years manufacturing metal roof panels. Some of our products, such as standing seam, are often used on low slope roofs as they offer exceptional weathertightness. However, we understand there are more options available to you when it comes to low slope roofs.
We have compiled the top 5 types of roofing materials you should consider when you have a low slope to help you choose which roofing material is best for you.
What Is A Low Slope Roof?
A low slope roof is a roof that has very little or no steepness. Typically, a roof that has a pitch of less than 3:12 is considered to have a low slope.
What Is A Flat Roof?
A flat roof is considered part of the low slope roof category but a distinction should be made between the two. Flat roofs are not entirely flat but are very close to being level. They usually only have a pitch of 1/4 inch to 1/2 inch per foot.
Flat roofs are most commonly seen in commercial applications. However, you will see flat roofs used in adobe style homes which are mostly found in the Southwest US and which draw inspiration from the Pueblo and Spanish Missions.
To determine the slope of your roof, we recommend reading:
Roof Pitch: An Easy Formula To Determine Suitable Roof Types
Where Are Low Slope Roofs Most Common?
Low slope roofing is most common in arid, or desert like, climates where there is a general lack of precipitation.
Low slope roofing is more prone to water damage when the roof is in an area with high precipitation. In these cases, if the roofing material used is not suitable for low slope roofing and has rainwater sit on it for an extended period of time, leaks can occur because the water is unable to runoff as easily as when it's on a standard or high slope roof.
Low slope roofing is also commonly seen on commercial buildings. This is because they are more cost effective compared to standard slopes and also allow businesses to store and maintain their A/C units on the top of the building.
What Are The Top 5 Low Slope Roof Options?
- Standing Seam Metal Roofing
- Built-up roof (BUR) membranes
- Modified Bitumen
- Single-ply
- Roofed Roofing
Standing Seam Metal Roofing
Standing seam metal roofing is sheet metal that has a flat appearance in the center and vertical ribs at the panel edges, creating a smooth, streamlined appearance.
Low slope standing seam roof
It’s the most weather-tight metal roofing system because it’s attached with concealed fasteners and does not have screws penetrating the surface like corrugated metal roofing does.
There are three different types of standing seam panels. For a low slope roof application, a double lock mechanically seamed system should be used for maximum weathertightness. This type of standing seam roof is an excellent choice in climates that have extreme weather conditions.
For more information on the different standing seam roofing systems, click the banner below:
Built-up Roof (BUR)
A BUR (built up roof) system, also referred to as a “tar and gravel” roof, is composed of alternating layers of bitumen and reinforcing fabrics, such as felt paper, and is topped with gravel to create a finished membrane.The multi-layer system creates exceptional protection and insulation.
BUR roofing has been around for more than a century and is a durable, low slope solution. Since it’s installed in large sheets, it provides a continuous sealed surface that effectively resists water.
Modified Bitumen
Modified bitumen (mod bit) roofs consist of roofing sheets made of asphalt that have been modified with rubber or plastic. Mod bit roofs are very similar to BUR systems as they both are installed in multiple plies. However the difference is in the modified bitumen’s additions to the asphalt.
Modified bitumen roofing hit the market in the 1970s as an enhanced version of a built up roof to offer greater flexibility and the ability to handle extreme temperature variations better than BUR. Sometimes the two are combined, offering what is known as a “hybrid roofing system”. In these instances, the modified bitumen also serves as the cap sheet of the BUR roofing system.
Single-ply
A single-ply roof consists of wide sheets of plastic membrane that are rolled out over the roof’s surface and then welded together. The result is a weathertight, durable roof.
The three main types of membrane used for single ply roofing are:
- Thermoplastic Polyolefin (TPO): Most common and economical.
- Ethylene Propylene Diene Monomer (EPDM): Black surface that is good for melting snow and heat gain in cold climates.
- Polyvinyl Chloride (PVC): Highly reflective, can reduce energy costs in warm climates.
Rolled Roofing
Rolled roofing, or asphalt roll, is a mineral surfaced oil-based asphalt product that comes in large rolls. It’s available in a wide variety of colors, styles and textures.
While both asphalt roll and asphalt shingles are considered to be similar, asphalt roll is not as durable, attractive or long lasting as asphalt shingles. Rolled roofing only lasts for approximately 5-8 years. Known for it’s easy installation, rolled roofing is best used as a cheap, temporary roofing solution or for applications on garages or sheds.
Underlayment For Low Slope Roofing
In addition to choosing the right roofing material for a low slope, you must also make sure to use the correct roof underlayment. Underlayment is critical, and often required by building code, for low slope roofing as it provides an additional layer of protection from water which helps reduce chances of leaks and water damage.
There are two main types of underlayment: felt and synthetic. Synthetic roof underlayment has superior durability, longevity and performance compared to felt. However, it is not for every type of application.
For more information on when to use and not use synthetic roof underlayment, we recommend reading:
The Top 3 Problems With Synthetic Roof Underlayment
Choosing The Right Low Slope Roof Option
Choosing the right roofing material is especially critical for a low slope roof as this type of roof is more often exposed to water, UV rays, debris, and foot traffic and must be durable enough to resist damage.
When deciding on the right material for a low slope, take into consideration:
- Climate
- Budget
- Longevity
- Aesthetics (if applicable)
If your roof has any pitch, then aesthetics do play a role in your decision. Standing seam is considered the premium choice in metal roofing not only for its performance and long lifespan, but also for its clean lines and enhanced curb appeal.
Learn more about standing seam metal roofing and the 3 types of standing seam panels that are available:
