TPO Roofing System
But roofing manufacturers say there is quite a bit to consider, especially when considering single-ply
systems. According to manufacturers, these systems continue to garner interest, thanks in part to the
cost and performance benefits they deliver.
Although varieties of single-plies have been around for more than 40 years, only in the last decade
has the full performance potential of the systems been realized with the advent of new thermoplastic
formulations. New plies also are increasingly economical, say manufacturers, and particularly favored
by consumers when they carry Energy Star ratings.
Single-plies exist predominantly as two types: vulcanized unweldable elastomerics -- nearly all of
which are based on an ethylene propylene diene monomer (EPDM) rubber -- and weldable
thermoplastics such as polyvinyl chlorides (PVC) and thermoplastic polyolefins (TPO).
EPDM remains a popular roofing choice because of its durability and economy, manufacturers say.
Usually ballasted or adhered, EPDM systems have a proven performance record after several decades
PVC has also been around for several decades; because of the formulation of PVC, many roofing
manufacturers recommend it for installations that require chemical-impervious roofing.
TPO is the fastest-growing category of single-ply systems. Manufacturers say its market share is
beginning to grow because TPO roofing costs are coming down and because of the numerous
benefits of using the material.
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"There's significant push for TPO systems because of its environmentally friendly nature, because it's
a recyclable product, and because of its energy-saving characteristics," says Mike McAuley, national
sales and marketing manager for Versico Inc.
But TPO systems are newer products that do not have the performance history of some single-plies.
Some manufacturers also say that TPO formulations continue to be tweaked to improve longevity and
"Ultimately, TPO formulation remains a balancing act between fire retardants in the formula and the
stability of UV-light protection elements in the formula," says Brian Whelan, vice president of sales
and marketing for Sarnafil.
McAuley agrees, adding that most, if not all, TPO systems remain in an "incremental improvement
stage." Manufacturers have established durable base formulations but introduce small changes to
improve certain qualities, including fire resistance.
TPO first was used more than 20 years ago to sheathe buried cable and protect other sub-grade
McAuley says specifiers in institutional and commercial facilities are learning about TPO
performance and more often choosing it over other single-plies because costs are coming down. He
says TPO material costs are higher than those for EPDM, but installation labor costs are lower.
Sarnafil's Whelan says another reason specifiers favor TPO is because uncolored versions frequently
carry an Energy Star rating. To meet Energy Star
"Increasing numbers of property owners seek the benefits of reflective roofing," says John Gardner,
low-slope roofing marketing manager for GAF Materials Corp. "You get the potential of energy
savings, with distinct environmental benefits and the good public relations opportunities that also
come with it."
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By reflecting solar energy, reflective roofing lessens summertime cooling loads, saving facilities
money. Because Energy Star roofing by definition has high emissivity -- giving off heat, rather than
holding it -- it also reduces the urban heat island effect, Whelan says.
Keeping it Clean
Over time, however, roofing materials accumulate dirt or grow mold, lessening roof reflectivity. To
continue reaping the benefits of reflective roofing, managers should clean the roof, using a power
washer, a minimum of once annually.
Mold is a sensitive topic for roofing suppliers and maintenance managers alike, one manufacturer
says. Some companies, including Stevens, use fungicides or algaecides in TPO formulations to
combat mold growth. But these biocides do not always prevent the buildup of mold and mildew, and
some might lose effectiveness over time.