Low Slope Metal Roofs: Increase the Benefits by Lowering the Pitch

Published October 16, 2015 by Whirlwind Team

low slope metal roof

Metal roofs are becoming an increasingly popular choice for new homes, businesses and commercial buildings. Even if the building is framed with wood, rather than steel, metal roofing systems offer an ultra-durable and sustainable choice, often lasting 50 years or longer with only a modicum of maintenance.


The slope of your building's roof is dependent on a range of factors, including the building's design, site location and climate. The slope of a roof is typically written as two numbers, separated by a colon such as 2:12. This indicates the slope of the roof is elevated two vertical inches for every 12 horizontal feet of roofing material. A low slope roof ranges from 1/4:12 to 3:12. 

Roof slope is important to the well-being and longevity of any building. The slope of the roof keeps water and snow melt moving down and away from building and can protect the building from wind damage. The same is true for debris, like leaves, dirt and branches, which can contribute to corrosion the longer they remain in physical contact with roofing materials.

Beware a Completely Flat Roof

Sometimes, you may see a low slope roof advertised as a "flat roof." However, most of the time these roofs will still have a very minimal slope so it's important you don't confuse the two. In almost all cases, a low slope roof will perform better than a flat roof.

There are inherent issues with flat roofs.

  • Code violations. While building codes vary by region, many building departments have a recommended minimum roof slope requirement. Often, the minimum roof slope will be 1/4:12. Anything less than this may be considered illegal and will have to be rebuilt (new construction) or may get you into trouble if an observant building inspector notices the violation while passing by. If you do opt to build a flat roof to accommodate a building's architectural designs, there will be strict rules about the materials you use to ensure the roof's safety and ability to prevent water damage.
  • You can't use metal roofing products. If you do opt to build your home or business with a flat roof, you will not be able to use metal roofing products for the simple reason that they cannot perform to their designed capabilities if standing water is a potential. If you are committed to green building practices and/or are attracted to the many benefits of a metal roof, you will have to build your roof with a minimal slope.
  • Water vulnerability. Standing water is the enemy of every roofing product. It causes organic materials to rot and allows mold and mildew to set in. Metal roofing products will begin to rust, and then seriously corrode. Water damage can spread from a flat roof to adjacent structural materials, leading to widespread damage throughout the building.
  • Limited by geography. Because of their inability to shed water and snow, your geographic location may dictate whether or not you can truly have a flat roof. In most cases, low slope roofs are recommended for the southwestern United States and geographic locations with a very mild climate.

5 Benefits of a Low Slope Roofing Systems

Low slope metal roofs typically consist of interlocking panels, called standing seam roofing, that range in slope from 1/4:12 to 3:12. These seams run vertically along the surface of the roof.

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Some of the benefits of this type of roof include:

  1. Long service life. Currently, a high-quality, standing seam metal roof that is designed and installed for your building's use and location will be warranteed for up to 40 years. Ongoing research shows that a well-maintained metal roof will last much longer than that, many metal roofs maintaining their aesthetic and functional value for 60 years or more without needing any significant repairs. This also means your roof benefits from more affordable lifetime costs as minimal maintenance and fewer needs for repair and replacement significantly reduce future financial responsibility.
  2. Sustainability. Steel and metal building products are typically made using pre- and post-consumer recycled materials. More importantly, most metal roofs can be up to 100% recycled at the end of their life cycle, when they are finally replaced or when a building is demolished. Your metal roof will earn points in LEED and other renowned green building certification programs.
  3. Energy efficiency. Metal roofs can be purchased as cool metal roofs, or with reflective and emissive coatings that reflect and radiate solar heat back into the atmosphere, maintaining a more comfortable interior temperature and reducing cooling costs by as much as 40% on average.
  4. Waterproof. Your metal building manufacturer can help you determine which type of low slope metal roof is best for your project and location. In areas with a more moderate climate, a waterproof roof is enough to route both rain and standing water off the roof and into a gutter and downspout system. If you live in an area with more severe winters, you will probably require a steeper roof slope.
  5. Lightweight. A low sloped roof requires less roofing material, which reduces the weight load placed on the structure. Typically, a low slope metal roofing system weighs between 40 to 135 pounds per 100 square feet, making them one of the lightest and easiest roofing materials to install.

In the right climate, a low slope metal roof makes the most sense for long-term durability, cost effectiveness and energy efficiency.

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