You want to install a metal roof on your home but your home has a really low slope. You may be wondering if a metal roof is a good idea, or even possible, when working with such a low pitch.
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, not every type of metal panel is the right fit for a low slope.
In this article, we discuss the appropriate metal panels you should consider when looking to install a metal roof on a low slope so you can decide on the right panel for your home.
Can You Put A Metal Roof On A Low Slope?
Just about any type of metal roofing panel will work with a 3:12 roof pitch or greater. However, when the pitch drops to a 2:12 or even a 1:12, you will have to use the right metal roofing panel profile. Low slope roofs are more susceptible to water damage because they do not offer much steepness for rainwater to runoff. If the water sits on the roof surface for too long, it can penetrate the roof, resulting in leaks and expensive repairs.
To avoid any potential damage, using the right metal panels that have maximum weather-tightness is critical to having a successful metal roofing system on a low slope. It’s also critical to use an experienced installer on low sloped roofs as this type of metal roof will be more susceptible to leaking.
What Are The Best Metal Roof Panels For A Low Slope?
Watch this video to learn more about metal panels that work best for low sloped roofs. We cover everything that is discussed in this article.
1. Snap Lock Standing Seam
Snap Lock standing seam, the most common type of standing seam, is a compatible metal panel for a low slope roof as it features a concealed fastening system.
By having hidden fasteners, it eliminates any screw penetrations on the surface where water could potentially seep through. Instead, the panels are installed by using standing seam clips and are snapped in place.
Snap Lock Standing Seam Specifications
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Seam Heights: 1.5" and 1.75"
- Panel Widths: 12", 14", 16", 18"
- Panel Lengths: Up to 52'. Lengths in excess of 52' will have to be roll-formed on-site.
Snap lock is a secure system, but not as weathertight as mechanically seamed standing seam because it does not have the extra seaming.
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For this reason, snap lock will perform better in more mild climates where heavy snowfall or rain is not as prevalent.
- This makes snap lock easier to install compared to mechanically seamed panels, as it requires less steps and labor.
What is the minimum slope requirement for Snap Lock metal panels?
Snap Lock standing seam panels are generally recommended for roof slopes that are a minimum of 2:12 to 3:12 depending upon the manufacturer's recommendations.
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Minimum pitch for low roof slope: 2:12
- Standard Recommendation: 3:12 or greater
2. Mechanically Lock Standing Seam
Mechanically seamed is a concealed fastener standing seam metal panel. The panel is designed to be used with clips that line up with one another so they can be locked together by a mechanical or hand seamer. The way the panels are fastened together makes it the most weather resistant standing seam roof and less likely to have any leaking issues.
Benefits of Concealed Fastener Mechanically Seamed Panels:
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Perfect for very low sloped roof (below 3:12)
- Greatest resistance against water leaks
- Tightly sealed seams and added underlayment create a watertight seal
- Excellent choice in coastal climates, regions with extreme weather conditions or hurricane zones
Standing Seam Panel Height Specifications
While WSMR carries standing seam panels with seam heights of 2”, you can find other panels on the market with heights of 1”, 1.5” or 2”. If you like the look of standing seam, we recommend a higher height as it makes the appearance of the seams more pronounced.
As you’ll see below, the higher the height, the lower your roof pitch will need to be.
- 2-inch double lock profile: Can be installed on a .5:12 pitch or greater with in-seam sealant.
- 1.5-inch double lock profile: Can be installed on a 1:12 pitch or greater with in-seam sealant.
Single vs. Double Lock Mechanically Seamed Standing Seam
Mechanically seamed panels can use one of two locking systems: single lock or double lock.
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Single lock has seams that are folded once (90 degrees)
- Double lock has seams that are folded twice (180 degrees)
- For maximum weather-tightness, we recommend double lock as they are more common, more secure, and have an overall better performance compared to a single lock system.
In-Seam Sealant Options For Low Slope Metal Roofs & Concealed Metal Panels
Roofs with low slopes (less than 3:12) require extra weather resistance. The sealant provides extra weather tightness which works well with low slope roofs where it is harder for water to runoff.
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NovaFlex Metal Roof Sealant is a non-corrosive, single-component, oxime-cured, silicone sealant and/or adhesive. This product is a general purpose compound that is used most frequently as a seam sealant or joint filler to help prevent a roof leak in metal roof systems.
- Butyl Sealant Tape is another option for increasing weather resistance. It's designed for side and end lap sealing of metal panels, roof vents and pipe flashing - providing optimum sealing in harsh environments. This is great for high temperature climates where the heat can soften the rubber adhesion, making for an effective thermoplastic bind to clean metal panels.
What is the minimum roof slope required for Mechanically Seamed standing seam metal panels?
Mechanically fastened standing seam panels can be installed on roof slopes as low as 0.25:12 (a 1/4-inch rise for every 12 inches of horizontal run). Depending on the manufacturer specifications and use of in-seam sealant, it's generally recommended for roof slopes that are a minimum of .5:12 to 3:12 for standard low slope roofs.
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Minimum Slope Pitch: 0.25:12 and 0.5:12
- Standard Low Slope Pitch: 1:12 to 3:12
3. Western Rib - 7.2 Panel
A 7.2 panel, also known as a structural box rib, is well suited for a low slope roof. While the panel does feature exposed fasteners, it also has high ribs that results in extra weather-tightness, strength and durability.
Each rib measures 1.5” high with 7.2” of spacing between ribs. The water has to rise to the level of the panel height to penetrate the panel seam and leak. On a low slope roof, when there’s heavy rain, it will not drain as quickly.
With such high ribs as those featured on a 7.2 panel, it makes it the most weathertight and low slope appropriate of all the exposed fastener metal panels.
Benefits of Exposed Fastener 7.2 Panels:
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Perfect for very low sloped roof (below 3:12)
- Greatest resistance against water leaks
- Tightly sealed seams and underlayment create a watertight seal
- Excellent choice in coastal climates or regions with extreme weather conditions
7.2 Panel Compared To Standing Seam
Though it is not as weathertight as either of the standing seam panels, 7.2 panel is also the most affordable and easiest to install option of the three panel choices mentioned in this article.
The exposed fastening system of the 7.2 panel allows it to be simply screwed down directly onto the roof deck. This makes it the most DIY friendly low slope option mentioned in this article.
7.2 panel also has the largest variety of color options compared to standing seam as it comes in colors in both SMP and PVDF paint systems.
Alternative Exposed Fastener Panels For Low Slope Roofs
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R Panel is also well suited for a low slope roof. While the panel does feature exposed fasteners, it has strength and durability from its 1.23” high ribs that makes it compatible with a roof with a pitch of 1 in 12 or greater.
- International Residential Code (IRC) recommends a standard pitch of 3:12 or higher.
What is the minimum roof slope required for 7.2 Panels?
For WSMR 7.2 Panels, we generally recommended for roof slopes that are a minimum of 1:12 to 2:12. Depending upon the manufacturer's recommendations, the minimum roof slope can range from 0.5:12.
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Minimum Roof Slope for WSMR 7.2 Panels: 1:12
- Check your manufacturer's panel recommendations for the exact slope minimum.
- Installation factors such as the proper sealant option, fasteners, and spec sheets differ depending on your specific panel manufacturer.
Slope Guidelines and Requirements
International Residential Code (IRC)
Exact minimum pitch requirements have been established by the International Residential Code (IRC) as well as the NRCA, Metal Construction Association (MCA), and major technical manufacturer systems. According to the International Residential Code (IRC), the set absolute minimum baseline of 0.25:12 (2% slope) for specialized systems and a minimum of 1:12 to 2:12 for standard systems.
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Ultra Low Slopes: 0.25:12 (2% slope) to 0.5:12
- Standard Guideline for Low Slopes: 1:12 to 2:12
Important Installation Factors
The primary function of a roof slope is to allow water to shed off of your building - preventing water build up and ponding. Here's some important installation factors that will optimize protections against water damage:
- Follow your manufacturer's panel specifcations to align with their warranty. For instance, the warranty might state "Warranty coverage applies only to installations meeting slope minimums of ___."
- Follow local building code compliance - especially for coastal regions and areas with extreme weather conditions. Most coastal high velocity hurricane zone (HVHZ) requirements expect advanced installation applications and inspections for buildings with a slope below 6:12.
- For longevity and optimal protections,
- Concealed fastener panels should be sealed with sealant in water penetration points and used in combination with water shielding roofing underlayment.
- Exposed fastener panels require proper fasteners with neoprene washers and proper spacing for high wind zones. Added sealant or butyl tape at horizontal laps will help prevent water leaks.
- Low slope roofs will require careful installation to ensure the best protection against water and wind damages.
Why does this matter?
Understanding minimum pitch is important to prevent water pooling, leaks, and premature failures. Installing a metal roof that is below a manufacturers’ minimum could void your warranty.
Check your local building codes and climate to optimize your installation process. Coastal regions and hurricane zones have enhanced requirements. This is where mechanically seamed panels and concealed fastener panels work to eliminate penetration points where water may enter.
In-Seam Sealant Options For Low Slope Metal Roofs
Roofs with low slopes (less than 3:12) require extra weather resistance. The sealant provides extra weather tightness which works well with low slope roofs where it is harder for water to runoff.
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NovaFlex Metal Roof Sealant is a non-corrosive, single-component, oxime-cured, silicone sealant and/or adhesive. This product is a general purpose compound that is used most frequently as a seam sealant or joint filler to help prevent a roof leak in metal roof systems.
- Butyl Sealant Tape is another option for increasing weather resistance. It's designed for side and end lap sealing of metal panels, roof vents and pipe flashing - providing optimum sealing in harsh environments. This is great for high temperature climates where the heat can soften the rubber adhesion, making for an effective thermoplastic bind to clean metal panels.
Roofing underlayment strategies, especially for low-slope roofs below 3:12, are required to prevent standing water from backing up and leaking into the structure. After working closely with contractors and architects, we've found that sharkskin underlayment pairs best with our metal roofing panels to create a complete waterproofing design. It's easy to install, performs well in all temperature conditions, and includes a 25 to 50 year warranty.
Choosing The Right Low Slope Option For Your Metal Roof
Choosing the right metal roofing material is important when you have a low slope roof to ensure your roof will enjoy the proper performance and longevity that metal roofing is known for.
Best Metal Panels For Low Slope Roofs |
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| Concealed Metal Panels | Best Uses For: |
| Snap Lock Standing Seam |
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| Mechanically Seamed Standing Seam |
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| Exposed Fastener Panels | Best Uses For: |
| 7.2 Panels (Western Rib) |
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| R Panel / PBR Panel |
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Your decision in choosing the right metal panel for low slope roofs might depend on your location's environment and building aesthetics. Ultimately, mechanically seamed panels are ideally the best for extreme conditions and ultra low slope roofs of 0.25:12 or greater.
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.
For more information about standing seam metal roofing and the 3 types of standing seam panels that are available:
If you're looking for the best exposed fastener panel for low slope roofs, check out our Western Rib 7.2 Panel. Besides being great for low slope roofs, 7.2 Panels has many features that could make this panel the best fit for your project. Read more here: 7.2 Panel- Structural Box Rib: Cost, Uses, And Benefits