by United Roofing MN | Aug 9, 2011
Minneapolis Metal Roofing Contractor MN If you live in a humid climate, you’ve probably seen the unsightly black staining that often occurs on an asphalt shingle roof after a few years. Unbeknownst to most homeowners, this common staining phenomenon is caused by airborne algae that collect on the roof and then grow in moist areas, producing roofing stains that look like black streaks. Since asphalt roofing shingles can absorb moisture and stay damp for extended periods of time, they can create a fertile environment for the growth of these algae stains and other microorganisms. Algae, Mildew, and Mold Stain Resistant Roofing Metal roofs are very resistant to algae, mildew, and mold stains for several reasons. First, the smooth, hard surfaces of a metal roof make if difficult for airborne debris, dust, and plant materials to collect. Also, metal roofing materials don’t absorb water, eliminating the damp, fertile, environment that can lead to growth. Finally, metal roofing materials can be thoroughly cleaned without risking damage to the roof. So, in addition to better protection against algae staining, a metal roof is also mold and mildew resistant. Eliminating these unsightly, and sometimes unhealthy mold and mildew stains from your roof will help ensure your home stays beautiful and maintenance-free for many years. Shown here is a typical example of algae staining and discoloration on an asphalt shingle roof. A metal roof is also among the safest of all roofs because of its durability and non-combustibility. Because metal isn’t combustible, metal roofing is fire-rated as Class A. In fact, when wildfires rage through housing developments, often the metal-roofed homes are the only...
by United Roofing MN | Jul 12, 2011
Fire Resistance Ratings In fact, the materials that you use for your roof must be fire resistant and have a rating to let you know how much safety and protection the roof will provide. Regardless of the type of roof you choose to have installed, it is important to understand fire resistance ratings and choose your roof according to the desired rating you prefer. Fire Ratings for Roofing Material The independent, for-profit company Underwriters Laboratories Inc (UL) has developed a series of laboratory tests to measure how well roofing materials (such as shingles) resist fires. These tests are widely accepted by the roofing industry, and the results are widely quoted in industry promotional materials. UL 790, the most widely quoted standard, tests roofing materials’ resistance to fires from external sources — fires that originate outside of the house (such as from a lightning strike). It should be noted that the fire rating is not earned solely by the physical properties of the roofing material, but also by installing the material in the manner recommended by the manufacturer. The UL assigns roof coverings a rating that ranges from Class A (the highest level of protection) to Class C (the lowest level of protection). There are three fire resistance ratings — Class A, Class B, and Class C. Class A offers the highest protection from fire while Class C offers the least amount of protection. A roofing material that receives a Class A, B or C rating should maintain its position on the roof following a fire, and is not expected to generate flying, burning, shards of shingle. Class A roof...