Selecting Metal Panels Based on Roof Slope

Posted on November 1, 2016 by Jason Allen

If you’re reading this article, then you are probably already aware that metal roofing can provide many benefits, including longevity, durability and water shedding—not to mention the aesthetic features of today’s metal roof products. When specifying a metal roof system, choosing the correct panel is a key factor. Roof slope is critical in determining that choice. Let’s take a look at some of the main things to consider when choosing a metal roof panel with regard to roof slope, including building codes, minimum slope requirements and typical applications.

Building Codes

Building codes are perhaps the most important driving force dictating the roof slope to choose. Different types of roofs have distinct specifications for installation. According to the 2012 International Building Code (1507.4.2 Deck slope), minimum slopes for roof panels need to comply with the following:

  1. The minimum slope for lapped, non-soldered seam metal roofs without applied lap sealant shall be three units vertical in 12 units horizontal (25-percent slope).
  2. The minimum slope for lapped, non-soldered seam metal roofs with applied lap sealant shall be one-half unit vertical in 12 units horizontal (4-percent slope). Lap sealants shall be applied in accordance with the approved manufacturer’s installation instructions.
  3. The minimum slope for standing seam of roof systems shall be one-quarter unit vertical in 12 units horizontal (2-percent slope).

Minimum Slope Requirements

Depending on the roof profile, there are minimum roof slope requirements for each panel, which need to be considered. The profile refers to the shape the metal sheets take when they bend to form panels. Metal roof slope is expressed by a ratio indicating the roof pitch, which notes the vertical rise of the roof (in inches) for every 12 inches the roof runs horizontally—in other words, dividing the vertical rise and its horizontal span. The most common slopes are: 3:12, 1/2:12 and 1/4:12. When looking at metal roofing panel, you will need to consult with the manufacturer to ensure that the metal panel you selected will work for your application.

MBCI Roof Panels and Minimum Slopes

Applications: Low Slope or Steep Slope

Commercial Application

A low-slope roof is one whose slope is less than 3:12. There are several benefits of a low slope roof. They have simpler geometry that is often much less expensive to construct and low slope roofs require fewer materials than a steep slope, which reduce material costs. Commercial roofs are typically low slope (less than a 3:12 slope), and larger than residential roofs. This is due to low slope roofs being a bit easier to build on large structures.

1/2:12 Metal Roof Slope
Cecilia Junior High in Cecilia, Louisiana uses 7,180 sq. ft. of MBCI’s SuperLok®. This panel requires a minimum slope of 1/2:12.
Residential Application

A steep slope roof is one whose slope is greater than 3:12. Steeper slopes are ideal for areas that have higher snow loads and will also prevent the possibility of ponding water on the roof. When it comes to residential construction, your roof is a visible part of the structure. Choosing a metal roof for residential construction involves choosing a panel profile that will be aesthetically pleasing.

Steel Slope Metal Roof
It is common to use steep slopes in residential applications, such as this home in Guntersville, Alabama that utilizes MBCI’s LokSeam® (requiring minimum slope of 3:12).

Conclusion

Regardless of whether you’re choosing metal panels for a commercial or residential structure, slope matters. Following common standards, doing your research and paying attention to manufacturer guidelines regarding minimum slope will ensure you’re reaping the full benefit of your metal panel selection.

For More Information

To learn more about metal roof slopes, check out:

Leave a Reply

Your email address will not be published. Required fields are marked *