Roofing update: which roof for your facility?

Roofing systems are some of the biggest assets facilities managers oversee - both in terms of size and cost. Making choices about product selection and maintenance requires knowledge. Associations that represent manufacturers of roofing systems common to commercial buildings - asphalt (modified bitumen and built-up roofing), metal, single-ply, and sprayed polyurethane foam - are available as information resources for building professionals. BUILDINGS has checked in with four major roofing associations for an update on the industry.

Asphalt Roofing Systems (Modified Bitumen, Built-Up Roofing)

If all building owners and managers followed the advice of officials from the Rockville, MD-based Asphalt Roofing Manufacturers Association (ARMA), facilities departments across the country could see a thicker bottom line.

That advice - strict attention to roofing maintenance, maintenance, and more maintenance - could mean the difference between simply repairing minor problems or recovering an entire roof, say ARMA officials.

Asphalt roofing products most commonly used on commercial buildings - modified bitumen and built-up roofing systems - are noted for their relative ease of repair, if problems are caught early. "A significant amount of premature roofing failures are simply due to neglect," says Helene Hardy-Pierce of TAMKO Roofing, Joplin, MO. Hardy-Pierce is chairwoman of ARMA's Built-Up Roofing Committee. She and Tim Kersey, of Siplast Roofing, Arkedelphia, AR, who is chairman of ARMA's Modified Bitumen Committee, both say asphalt roofing products are like any other roofing products when it comes to maintenance - they must be inspected in the fall and spring, after severe weather, and after completion of construction projects that may have disrupted roofing systems.

Too often, the roof goes neglected until water leakage occurs. "The roof needs to be maintained like any other building system," Hardy-Pierce says.

Asphalt roofing products have maintained a steady market share in the commercial buildings industry in recent years. Modified bitumen systems, consisting of asphalt enhanced with either Styrene Butadiene Styrene (SBS) or Atatic Polypropylene (APP), are usually reinforced with polyester, fiberglass, or both. Placed on a reinforcing carrier, the modified bitumen is cooled and rolled up into a prefabricated waterproof sheet that is installed on the rooftop. These systems are well-suited for various types of roof construction, and are usually applied by mopping (SBS), torching in place (APP or SBS), cold adhesive, or self-adherence.

Built-up roofing systems, created with alternating layers of felt and coal tar, are adhered to an insulation layer, or base sheet, that is attached to the roof deck. Bitumen provides waterproofing, while the felts distribute building stress, provide the means for multiple layers of bitumen, and help serve as a fire retardant.

Both types of asphalt-based systems can be maintained fairly easily by building professionals trained in roofing inspection. Still, ARMA officials stress the need for regular checkups.

"If all building owners would go inspect the roof twice per year, they could increase the life of the roof by several years," says Kersey.

For more information on asphalt roofing systems, contact the Asphalt Roofing Manufacturers Association at (301) 231-9050.

Sprayed Polyurethane Foam Roofing Systems

Options are evolving quickly for building professionals interested in sprayed polyurethane foam roofing systems - ranging from faster-drying surface treatment to brilliantly colored coatings.

Foam roofs include an alliance of sprayed-on insulating foam, and a protective layer (usually a coating or gravel) that shelters the foam from damaging ultraviolet (UV) light. Roofs with unique configurations, or those with a slope to drain, are good candidates for sprayed polyurethane foam.

According to Mason Knowles, assistant director of the Washington, D.C.-based Society of the Plastics Industry's Polyurethane Foam Contractors Division, popularity among foam roofing is growing. "We're seeing a lot of foam roofing being specified now in buildings, rather than just retrofit, although retrofit is still about 80 percent of our business." Knowles cites interest in energy consumption - and the insulation benefits of sprayed polyurethane foam - as catalysts for the growth. Foam roofs are used in climates from Canada to southern Texas, he says, adding that recent research shows some foam roofs have successfully weathered the elements for more than 25 years.

Recent changes in technology may also fuel interest in this roofing option. "There are a lot of new coating products on the market," says Knowles. And coatings are critical to a foam roofing system; sound protection from UV light is vital to system effectiveness.

Three major developments in acrylic coatings include: (1) Faster-drying acrylic resins. This technology produces coatings that usually dry in half the time of standard formulas, Knowles says.

(2) "Snap set" coatings. This style contains a catalyst that is sprayed on the coating's surface just after application, instantly setting the coating surface. Suitable for areas prone to sudden showers or heavy dew, this application prevents wash-off, but cure time is not affected.

(3) Color-changing coatings. One coating option includes a formula that goes on dark but dries to a white finish. The dark color absorbs the heat, helping cure the material faster.

Customized colors are also an option in roof coatings. One manufacturer has presented a polyurea coating that is offered in a range of colors, Knowles says. "It can be tinted with dyes, so it offers fairly bright colors."

Foam roofing proponents say that, in many retrofit cases, foam roofs can be re-coated or renewed without tear-off - an environmental bonus.

About $0.22 billion was spent on sprayed polyurethane foam roofing in 1994, according to the Rosemont, IL-based National Roofing Contractors Association (NRCA).

For more information on sprayed polyurethane foam roofing systems, contact The Society of the Plastics Industry, Inc./Polyurethane Foam Contractors Div. at (800) 523-6154.

Single-Ply Roofing Systems

Sales of single-ply roofing systems continue to increase, industry insiders say, because building professionals are attracted to its performance - and cost.

Best suited for roofs with wide open areas, single-ply roofs are comprised of huge plies of man-made rubber that are placed on the rooftop and seamed into place with tapes or adhesives. Options typically include thermoset membranes (compounded from rubber polymers); thermoplastic membranes (based on plastic polymers, made flexible by plasticizers); and modified bitumen membranes (modified asphalt that incorporates rubber or plastic for increased flexibility). Single-ply systems can be moored by using fasteners, by ballasting the membrane, or by full adhesion, which involves use of a contact adhesive.

Recent technical developments have focused an seaming techniques for EPDM (Ethylene Propylene Diene Polymer - the most commonly used synthetic rubber), says David Roodvoets, of Westerville, OH, technical director for SPRI, a Needham, MA-based association that represents manufacturers of single-ply and other roofing systems. "Many manufacturers are coming out with weldable rubber," says Roodvoets. The advantage? "Any heat-weldable seam is absolutely positive. If it's made right, there's no potential for it to deteriorate in moisture or heat stress, or other kinds of conditions."

Building professionals are also showing high interest in manufacturers' offerings of thick, double-sided tape that is placed between the EPDM sheets to join seams. "Marketers are selling more and more products with taped seams, rather than adhesive seams. The tape gives more mass in the seam area. Tensile data shows these are stronger seams, at least initially," Roodvoets says.

Interest in energy efficiency continues as an issue throughout the industry. Recent research by Patrick Downey, a commercial roofing professional with Merik, Inc., Atlanta, shows that white-surfaced single-ply roofs and roofs with new white coatings reflect - rather than absorb - up to 80 percent of solar energy, helping manage interior cooling loads.

The single-ply roofing market has been fairly active during 1995, single-ply roofing experts say. Commercial building owners, apparently feeling more confident about finances, are freeing up funds for projects such as roofing. "The economy is very good for roofing right now." Roodvoets adds. Most work - 60 to 70 percent - focuses on re-roofing projects vs. new construction.

Single-ply roofing sales were at $3.4 billion in 1994, according to the NRCA.

For more information on single-ply roofing systems, contact SPRI at (617) 444-0242.

Metal Roofing Systems

The need for a new, 40,000 square foot roof at Pleasant Grove Elementary School in Graham, NC, was complicated by the two existing roofs that remained on the building. But building professionals found an option that helped them avoid tearing off the two deteriorated systems - a standing seam metal roof - which was installed over existing materials.

It also provided an attractive life-cycle cost analysis, according to officials from the Metal Building Manufacturers Association (MBMA), Cleveland, OH. "A standing seam metal roof fulfills any building owner's need for durable, long-term protection against virtually any type of weather," states Lee W. Shoemaker, MBMA's director of Research and Engineering. MBMA officials say metal roofing is gaining increased attention from building owners and managers.

Metal roofing systems range from ornate, hand-crafted architectural designs to structural metal systems known for their durability and weathertightness. More than 1.5 billion square feet of standing seam metal is installed each year, used in about two-thirds of all new construction in the low-rise commercial and industrial buildings sector, according to the MBMA.

Structural metal systems, common for low-slope applications, are installed watertight and placed on metal supports. Galvalume, which is steel coated with aluminum-zinc for corrosion protection, is the most common metal chosen for structural applications.

Architectural systems, on the other hand, depend on high slope for water drainage and require that the metal be supported on a continuous deck. A base felt is also needed for moisture protection. Copper, zinc, aluminum, and steel - often painted to enhance aesthetics - are typically used in architectural roofing. These often include visually exposed roofs, mansards, fascias, and similar applications.

Growth in the use of metal roofing has been linked by industry officials to its weathertightness. In standing seam systems, special sealants are factory-applied inside the system's raised seams, and automatic field-seaming machines produce weathertight connections between metal roof panels.

The metal roofing systems market cashed in at $0.43 billion in 1994, according to the NRCA. That figure is projected to total out at $0.51 billion in 1995.

For more information on metal roofing systems, contact the Metal Building Manufacturers Association at (216) 241-7333.

RELATED ARTICLE: Roofing Terms

* Anchor bolt: A steel bolt usually fixed in a building structure with its threaded portion projecting; used to secure frameworks, timbers, etc.

* Boot: A bellows-type covering to exclude dust, dirt, moisture, etc., from a flexible joint.

* Bull: Roofers' term for plastic cement.

* Cricket: A superimposed construction placed in a roof area to assist drainage.

* Flashing: The system used to seal the edges of a membrane at walls, expansion joints, drains, gravel stops, or other areas.

* Flood coat: The top layer in an aggregate surface, built-up roofing membrane.

* Jack: A flanged metal sleeve used as part of the flashing around small items that penetrate a roof.

* Overlay: The practice of applying new roofing over existing roofing material.

* Pond: A roof surface that is not completely drained.

* Purlin: A structural member laid horizontally on the rafters.

* Shark fin: An upward-curled felt side lap or end lap.

* Shoe: Curved outlet at bottom of downspout.

* Spud: To remove embedded aggregate from a built-up membrane surface.

* Stack vent: Vertical outlet in a built-up roofing system designed to relieve pressure exerted by moisture vapor between the membrane and deck.

* Standing seam: A seam consisting of upturned ribs, made by turning the edges of adjacent metal panels and then folding them.

* Strawberry: A small bubble or blister in the flood coating of a gravel-surfaced roof membrane.

* Yellow-jacket: An ethylene fiber material used as reinforcement of plastic cements.

SOURCE: GLOSSARY OF TERMS, ROOF CONSULTANTS INSTITUTE, RALEIGH, NC.