SCHOOL ROOF RETROFITS
- By Charles E. Praeger
- November 1st, 2003
If I had my way, all school buildings would have metal roofs, says Len Hindsman, assistant superintendent of Operations for Bibb County Public Schools in Bibb County, Ga.There’s nothing better. They last a long time, sun and water won’t destroy them and water gets off immediately.
Hindsman has a depth of experience with roofs, both traditional built-up and metal types. Through the years, he has been involved with retrofitting 25 school roofs with new standing seam metal roofs, both in Bibb County and Columbus, Ga.
Research conducted in 2001, by Ducker Worldwide for the Metal Building Manufacturers Association (MBMA), shows that new metal school roof projects totaled approximately 262 million sq. ft. last year and is expected to grow to 307 million sq. ft. by 2007.
Metal roofs provide schools with durable, long-term protection against any type of weather; can help lower the energy required to heat and cool the building when coupled with an efficient insulation system; significantly add to the facility’s aesthetic appeal; and reduce the need for costly, ongoing maintenance.
Longevity is a critical advantage, as well. Many metal roofing systems manufacturers provide warranties for 20 years or longer. An independent consulting engineering firm did research on 20 roofs across the country that were at least 25 years old and had been made with a 55 percent aluminum-zinc alloy coated sheet steel (better known as GALVALUME). The firm found that these roofs had another 10 to 15 years of useful life left.
Given the fact that the lifespan of a metal roof is higher than built-up flat roofs, the cost of specifying a metal roofing system becomes much less of a consideration when spread out through the years of the roof’s usage. In fact, it can be less expensive to add a new metal roof over the existing built-up roof, eliminating the need to remove the old one and replace it.The price of installing a new metal roof may be higher than removing and replacing an old one, but the predictability of long-term success with metal is much higher, says Wayne Reed, vice president of Columbia, S.C.-based architectural firm W. Powers McElveen and Associates.
The Watertight Advantage
One of the most oft-cited advantages of standing seam metal roofs is their ability to provide substantial water tightness.
Here in the South, many old schools still have flat roofs, says Roy L. Denney, Jr., CEO of Southern A&E, an Austell, Ga.-based architectural and engineering firm. Water from rain and snow will collect on a flat roof and eventually find its way into the building.
The critical difference between traditional flat built-up school roofs and a new standing seam metal roof is slope, which allows water to immediately run off.
Slope is critical to new roofs, says Denney. A 3:12 slope (three-in. rise for every 12 in. of roof length) is the most practical and economical slope in K-12 facilities because typical classroom wings are 70 ft. wide, and that width lends itself very well to that pitch. Not only is a 3:12 slope architecturally attractive in school settings, it quickly allows water to drain, rather than collect.
Why a pitched metal roof? Built-up roofs basically tear themselves apart after a time because they lose the ability to expand and contract. Within a couple of years, a built-up roof may develop a leak, and even when you repair that spot, it seems you spend the rest of the time chasing the leak around the rest of the roof, says Wayne Fullmer, vice president and project manager for M.A.R. Construction Company, Inc., Lexington, S.C., the contracting firm that replaced the East Side roof.
Designed as a water barrier, the raised seams on metal roofs facilitate water drainage. The panels are joined together by a weathertight seam raised above the roof’s drainage plane. Special sealants are factory-applied inside the seams during roll forming of the panel. The system’s concealed clip assembly is roll-formed or crimped into the panel seams without penetrating the steel weathering membrane. These clips perform two functions: they secure the panels to the structural system and they enable the roof to expand and contract.
Another advantage of metal roofing systems is the reduced need for maintenance. Any roof requires periodic walk-throughs, but with a metal roof, you basically go up once in the spring and once in the fall. It’s preventive maintenance, rather than repairs, says Fulmer.
Today’s steel roof is yesterday’s discarded refrigerator, automobile, building materials and other post-consumer products. More steel is recycled each year than all other materials combined. Many products from metal roofing system manufacturers contain steel made from discarded steel goods that might otherwise end up in a landfill. From an energy standpoint, standing seam metal roofs can bring some benefits to a school’s energy budget. A pitched roof creates an attic space containing an insulating air pocket that helps control the amount of energy needed to heat and cool the building.
Fiberglass blanket insulation is the most common material used in new standing seam metal roofs and retrofit projects. On some retrofit projects, unfaced fiberglass insulation is simply laid directly on the existing roof surface before the new standing seam roof is installed. In other projects, the insulation blankets are installed directly under the panels and stretched over the supporting structural members.
Metal roofs can be installed year-round. When installed over an existing roof, a standing seam metal roof can often be applied with minimal structural modification to the existing building. A new metal roof can be installed with little or no interruption of operations or inconvenience to students, teachers and administrators.
Standing seam metal roofs can also be designed to carry a Factory Mutual Class A fire rating, substantially reducing the building’s insurance rates. They also stand up to high winds. The durability of metal roof panels is further enhanced through the use metallic coatings applied to the base steel.
As more school administrators, architects, engineers and contractors specify metal roofs for their retrofit projects, Len Hindsman gets a little closer to his wish that all roofs be made of metal.