What’s the Difference Between Water-resistant and Water-shedding Metal Roofs?

It’s not necessary for the average homeowner to understand all the technical specs of metal roofs when considering having one installed.  Still, it never hurts to be familiar with some of the terminology commonly used when talking about these roofs.  If you’ve investigated metal roofing, or if you currently have one on your home, you may have heard the terms “water-resistant” and “water-shedding.”  Here’s what those terms mean.

Water-resistant and water-shedding refer to the pitch of the roof, not to the materials that make up the roof.  A pitch of 3:12, for example, means that for every 12 feet, there is a three-foot rise.

Where these two terms are concerned, a water-resistant roof (or section of the roof) has a pitch of 3:12 or less.  Roofs with greater pitches are labeled water-shedding roofs.

Because of a water-resistant roof’s lower pitch, water moves across it more slowly, making it unnecessary for there to be a secondary membrane beneath the roof to keep water from leaking into the home.  The steeper pitch of water-shedding roofs causes water to move much faster, creating the need for an underlying membrane.

Water-resistant roofs

Roofs with lower pitches normally don’t shed water with great efficiency.  This can result in water that pools and stays in place for some period of time and finds its way into any gap or opening in the roof.  For this reason, quality, professional installation of the metal roof is critical.  A badly installed water-resistant roof can lead to serious water damage to everything below the roof including insulation and decking as well as contents within the home.

The best water-resistant metal roof is a standing seam roof with seams that are two inches high at minimum.  Water is prevented from entering between the panels because of mechanical seaming of the joints.

Water-shedding roofs

Water will move faster across roofs with pitches greater than 3:12.  Most residential roofs fall between 4:12 and 9:12, which provides for maximum water shedding.  Faster-moving water, however, doesn’t mean precautions aren’t necessary to prevent leakage.

These precautions include a membrane or moisture barrier that’s #30 felt or greater over a solid deck.  The most efficient (and most expensive) membranes are “peel-and-stick,” which are less likely to tear and will create a solid seal around nails, screws and other fasteners.

Advantages of metal roofs

When the highest quality materials are used, and when the metal roof is installed by experienced roofers, you have an investment that will begin paying you back immediately.  Regardless of the pitch angle of a roof, certain steps must be taken to prevent leaks and excess condensation.  Expert installers know all these steps.

What kind of advantages do metal roofs bring?

• Reflection of heat and sun rays resulting in cooler interior temperatures during the summer
• Long-lasting – 50 to 60 years should be expected
• Ultra-durable against hail, heavy winds, corrosion and rust
• Can return up to 85 percent of the cost of the roof upon sale of the home
• Great looks with a variety of colors and panel styles

If you’d like to know more about the benefits of a new metal roof, contact the experts, Advanced Aluminum of Lakeland, FL, at (863) 648-5787.  We make top-grade metal roofing materials that are used by leading contractors throughout the Lakeland region.