Roofs

11 More Helpful Design Tips for Low-Slope Roof Systems

BD&C asked a panel of roofing experts for their advice about what design and construction professionals should do to ensure a successful low-slope roof project. The panel consists of: Tom O'Connor, FAIA, VP and director of building technology for Detroit's SmithGroup; Richard Koziol, AIA, senior consultant with Wiss, Janney Elstner Associates Inc., Northbrook, Ill.; and Greg Doelp, associate, Simpson Gumpertz & Heger, Waltham, Mass. Here is their advice:

  • Coordinate, coordinate, coordinate. Coordinate the building design with expected construction activities to minimize construction traffic from trades other than the roofers on the newly installed roof system.

  • Don't turn the roof into a staging area. During construction a newly installed roof should not be permitted to be a staging area for other trades. However, if this is necessary, consider installing a new roof in stages. Install the first ply to weatherproof the building and to provide a surface for others to work from and to take construction activity abuse. When those activities are done, patch the first ply and add the second ply to the roof system to complete it.

  • Make room for maintenance. Where roof-mounted equipment is specified (e.g., HVAC equipment, cooling towers, satellite and other antennas, etc.), use a two-step roofing system to accommodate construction traffic.
    Design a functional layout of mechanical and electrical systems and include step bridges as required for easy maintenance and use of controls. Construct equipment frames high enough above the roof surface to allow roofing personnel to get underneath the equipment to maintain and replace the roof. Follow National Roofing Contractors Association (NRCA) guidelines for this — they have a good chart showing recommended clearances in their Manual of Roofing and Waterproofing. For more, see www.nrca.net/pubstore/manual.asp?ProductID=243.

  • Design for future use. Design the roof system for future growth and adaptation of communication antennas and dishes to allow for easy replacement and mounting without damage to the roof.

  • Take a look at LEED. If you're shooting for LEED certification, your choice of roofing system may be limited. Green roof system selection and detailing (for white or vegetated roofs) should be conducted by an experienced professional. If you're not expert in this area, hire a consultant.

  • Conduct flood tests. Flood testing of certain areas may be warranted for high-risk installations and should be mandated for all green roofs — any system with significant overburden or critical internal areas requiring protection.

  • Consider rising walls. Address leakage from walls that rise above the roof — walls of adjacent buildings, penthouse walls, and rising walls often seen on hospital projects.

  • Think about the people in occupied buildings. On roof replacement projects on an occupied building, consider the impact of the roofing work on building occupants and building operations. These include noise from rooftop traffic, demolition, or installing fasteners; odors from kettles of hot asphalt, adhesive fumes, and solvent fumes; and dust from debris attached to the roof deck, such as old, crumbly spray-on fireproofing, old, crushed insulation, or roofing that falls through joint holes and openings in the metal or wood roof deck.

  • Consider interference from electrical conduit attached to the underside of the roof deck if you plan to fasten into the existing roof deck.

  • Build to code. Make sure your new roof design meets the requirements of the local building code. Review code requirements, functional and client needs, and incorporate these into the design. Consider such factors as:

    • drainage (function and capacity)

    • slope to drain (¼ inch per foot in most codes)

    • emergency overflow drains/scuppers

    • wind uplift loads

    • dead and live loads

    • fire-resistance ratings and fire protection

    • energy code requirements

    • thermal insulation needs

    • reflectance and emissivity of membrane

    • whether UL or Factory Mutual requirements need to be met.

  • Use cover boards. On fully adhered roof systems, use cover boards. Don't adhere directly to polyisocyanurate foam insulation. NRCA has published a technical bulletin on this issue at www.nrca.net.

For 10 additional roofing tips, see the September 2004 issue of BD&C (p. 55), or visitwww.bdcmag.com/magazine/articles/bdc0409roof.asp.

Making Waves

Polyurethane foam insulated panels provide the ideal backdrop for dramatic wave elements that top the new 90,000-sf printing facility for Grand Rapids Press in Grand Rapids, Mich. The "river waves" reflect the newspaper's heritage and history in the city, according to design architect Dario DiMare of Dario Designs Inc., Framingham, Mass. DiMare specified CF24A panels for their contemporary appearance, light weight, low maintenance, and efficient insulation.

Metl-Span.

Reader Service No. 217

Roof Revival

After a tornado completely destroyed its community center, the village of St. Peter, Minn., decided to build a new, 85,000-sf facility that maintained the historic image of the original structure. Architect Bryan Paulsen of Paulsen Architects, Mankato, Minn., replicated the old roof using two types of standing-seam aluminum metal roof panels: 13,000 sf of Tite-Loc panels finished in Mansard Brown cover the gymnasium and 25,000 sf of Snap-Clad panels top the remaining portion of the building. The panels were factory formed in lengths up to 55 feet for fast installation.

Petersen Aluminum Corp.

Reader Service No. 216

Puncture-Resistant TPO Roof System

Roof system combines the durability of a rubber membrane with the heat-welding properties of thermoplastic in an adhered application. UltraPly is a reinforced TPO membrane with an external backing of 8-ounce, non-woven polyester that resists puncture damage from above and below. The white membrane roof meets Energy Star's requirements for solar reflectivity.

Firestone.

Reader Service No. 233

Looks Like Metal

Roofing system combines the sleek appearance of a metal roof with the watertight integrity and low maintenance of a thermoplastic membrane. Decor Roof Systems utilize the Sarnafil G410 membrane installed over a roof board, insulation, vapor retarder, and structural decking. Two rib detail options are available: Decor Batten is a large rib ideal for very large or tall buildings, or for aesthetic emphasis; Profile is a smaller rib for a less pronounced appearance.

Sarnafil.

Reader Service No. 231

New Wall Profiles

Metal roof and wall panel line has been expanded with four new wall panel profiles. The R-Mer line of through-fastened metal wall panels is available in a variety of colors, in 12-, 32-, and 36-inch widths, and in exposed- or concealed-fastener profiles.

The Garland Co.

Reader Service No. 232

Back on Top

University of Missouri tipped off the Big 12 basketball season in style last month, edging Iowa State 62-59 on its new home court: the $75 million Mizzou Sports Arena. The 15,000-seat facility, designed by 360 Architecture and built by J.E. Dunn Construction, both of Kansas City, Mo., is topped with a standing-seam metal roof that consists of a 3-inch acoustical deck, rigid insulation, and 2 inches of blanket insulation beneath 24-gauge seamed panels. The university favored the MR-24 metal roof over a single-ply membrane because it matches the roof of a football practice facility nearby.

Butler Manufacturing.

Reader Service No. 205

Tin-Coated Roof

Appearance and durability were the main factors in the selection of a zinc/tin-coated stainless steel roof for the newly renovated and expanded Middletown (N.J.) Library. The 20,000-sf metal roof, which covers the library's new circular addition as well as a complex cone-shaped roof section, does not require painting and will weather naturally to a warm, gray patina.

Follansbee Steel.

Reader Service No. 211

Revival at Coney Island

The reconstruction of Coney Island's historic Stillwell Avenue subway terminal is nothing short of electrifying, as rusted, corrugated steel canopies have given way to sweeping triple-vaulted skylights that generate enough solar energy to light 40 homes for a year. The largest above-ground subway station in New York City, the renovated terminal is topped with 76,000 sf of photovoltaic laminated glass that converts sunlight into 250,000 kW hours of electricity annually. To reduce costs and installation time, supplier Traco recommended that the PV glass modules be framed in groups of five at the factory. Each 5×25-foot section was lifted by crane onto the steel structure and bolted into place, reducing labor costs in the field by 50%.

Traco.

Reader Service No. 225

         
 

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