Metal Roofing Underlayments Protect Structures in Hawaii

The newly constructed Safeway Shopping Center, Honolulu, happens to be the largest Safeway on the Hawaiian Islands. It contains a parking garage below—in part, because of its location in a densely populated neighborhood.

The underlayment manufacturer worked on and approved a design in which the underlayment could be installed directly on the metal deck.

The underlayment manufacturer worked on and approved a design in which the underlayment could be installed directly on the metal deck.

ITS METAL ROOF WAS INSTALLED by Kapolei, Hawaii-based Beachside Roofing, which has been doing business in Hawaii for more than 25 years. The company, which installs all kinds of roofing and waterproofing systems, specializes in high-rise buildings, resorts and complex projects.

The 20,000-square-foot metal roof on the Safeway store had to meet strict color requirements in keeping with the Safeway brand. The color of the roof is Gargoyle, which is a greenish-brown.

The metal roofing was designed to be installed over corrugated 20-gauge steel decks. The underlayment manufacturer worked on and approved a design in which the underlayment could be installed directly on the metal deck.

The metal deck (HSB-36SS type) was installed with the wider corrugations facing up and parallel to the eaves (horizontally). The self-adhering underlayment also was installed horizontally, and the metal panels were then attached to the horizontal corrugations of the deck using panel clips and self-drilling fasteners penetrating through the underlayment into the flattop of the corrugations of the steel deck.

The self-adhering underlayment also was installed horizontally, and the metal panels were then attached to the horizontal corrugations of the deck using panel clips and self-drilling fasteners penetrating through the underlayment into the flattop of the corrugations of the steel deck.

The self-adhering underlayment also was installed horizontally, and the metal panels were then attached to the horizontal corrugations of the deck using panel clips and self-drilling fasteners penetrating through the underlayment into the flattop of the corrugations of the steel deck.

The walkability of the underlayment was an important factor, considering that the roof slope was 4 inches per 12 feet in some places. Also, the 120-day exposure allowance for the underlayment was reassuring, though not necessary for this project.

The metal roofing system included many architectural elements, such as canopies, penthouses and mansards. It covers not just the Safeway supermarket, but also other shops in the Safeway Shopping Center. The way the metal was used architecturally really dressed up the exterior of the project.

Secondary Water Barrier

A self-adhering metal roofing underlayment, like the one on the Safeway Shopping Center, perfectly complements metal roofing panels. The underlayment provides a watertight secondary membrane while the metal panels serve as the primary roof to protect against wind-blown objects and UV radiation. If the primary roof is damaged, the secondary roof acts as the water barrier.

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About Scott Ai

Scott Ai is vice president of Estimating for Beachside Roofing LLC, Kapolei, Hawaii, and vice president of the Roofing Contractors Association of Hawaii.

Comments

  1. Cal Driver says:

    Great tips. Thanks so much. For places with heavy rainfall (I’m in Western Washington right now), metal roofing is a must. I’d also agree that long-exposure and water barrier capability are “important factors,” although I’d say that’s a bit of an understatement. The suspense of living in a rainy climate with a leaky roof can be a killer. Thanks for sharing.

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