Buildings Magazine - Buildings 2/2015

continued waterproofing integrity suggests an excellent return on initial investment, meriting the serious consideration of any owner expecting to hold onto a property for 25 years or more.

Three Must-Dos for Extending Service Life

If extended service life is an appropriate goal for your roof, there is much you can do to improve your odds of long-term success. The three roofs studied have effectively doubled the life span expected of today’s commercial roof offerings thanks to these three common factors.

1) Specifying quality materials.

All three roofs were on manufacturing buildings with higher-than-average foot traffic, which required systems with high puncture and tear resistance. Given the thermal variations in Indiana, a membrane with a generous safety margin in regards to elasticity and a reinforcing fabric with significant tensile strength were appropriate.

In all three cases, the owner chose a
bitumen blend of SBS polymers with a
mixing process that ensured uniform
dispersion, plus a high-performance
scrim that added tensile strength several times greater than
the industry standard in the early 1980s when the roofs
were installed.

However, the membrane only tells part of the story. The specifications also called for a comparably high level of quality in all other system components, including two courses of insulation, multi-layered construction, a high-performance waterproofing cap sheet, and a belt-and-suspenders flood coat of gravel surfacing. Some may call these specifications over-engineered, but in my mind, the sustained performance of such redundant systems is attributable in no small part to the quality of the materials used.

2) Vigilant monitoring during installation. The highest quality materials can still result in a premature roof failure if they are improperly installed. Ensure every system component is added in full compliance with the specification and the manufacturer requirements. This means vigilant job site monitoring during construction is recommended – in the case of these roofs, this task was performed by a representative of the membrane manufacturer responsible for warranting the systems.

3) Long-term preventive maintenance. The final element indispensable to extending roof life is proactive maintenance. Roofing success is a responsibility shared by the building owner. No homeowner would expect a roof to survive multiple freeze-thaw cycles without cleaning out roof gutters periodically, and the typical commercial roof experiences far more foot traffic, exposure to potential punctures and tears, and degrees of building movement. Commercial roofs also support far more roof equipment, making preventive maintenance vital to long-term performance.

The owner of these three roofs collaborated with his roofing partners across decades for ongoing inspections of flashings, gutters, drains, and other critical components while diligently performing any required minor repairs. As a result, all three exceeded their warranted performance.

There can never be one single roof system application that solves every problem, but this approach to roof system selection, installation, and maintenance has already proved successful and cost-effective. If owners are to ever achieve a roof service life that lasts as long as the building itself, they must move forward grounded in these principles. B

Dr. Heshmat O. Laaly is an analytical research chemist, professional roofing consultant, and president of Roofing Materials Science and Technologies in Los Angeles, CA. He is also the author of Science and Technology of Traditional and Modern Roofing Systems. For more information, see www.roofsandroofing.com.

THIS FOUNDRY ROOF, reinforced modified bitumen cap sheet.

THE WATERPROOFING INTEGRITY of this modified bitumen roof was laboratory tested after 25 years of service. It retained 80% of its tensile strength while maintaining low-temperature flexibility and compound stability well within the requirements of ASTM D6163.