Solving Substrate Dilemma

The same sheathing is used to back the several different types of exteriors featured on Addison Place Shoppes of Alpharetta, Ga.

Anew, all-in-one solution solved an exterior dilemma at Addison Place Shoppes, Alpharetta, Ga. The specifications for the 42,000-sq.-ft., three-building retail center required four types of exteriors: brick, stone, lap siding and EIFS [exterior insulation and finish systems].

“The project also called for two substrates: cement board to back the brick and stone, and traditional sheathing to back the lap siding and EIFS,” said Glenn Ulmer, project manager and CFO, Total Dimensions, Dawsonville, Ga., who served as the contractor for the center.

Besides featuring the multiple exterior finishes, the 42,000-sq.-ft., three-building complex incorporates numerous molding insets and buildouts, for a total of 10 different exterior details. Making matters more complicated, the architect wanted many of the features built right into the finish, so that a brick exterior, for example, would transition directly into a stucco-like finish.

“In some places, the brick comes right up to our bump-outs,” Ulmer said. “Then it picks up with an EIFS band, which steps out, then in, and then goes to the top of the building. We had framing to tie in with trusses, and rooftop parapets to build. There were balconies and overhangs to do as well.”

Given the detail of the work, Ulmer came to the conclusion that using one substrate throughout the project would not only be economical and save time, but also ensure a high standard of construction. With a multi-substrate system, the foremen would have had to double-check every square foot of the exterior wall space to make sure that the correct backer was behind each finish.

“We didn’t want to use two substrates,” Ulmer said. “We wanted just one.”

He recommended USG Corp.’s FIBEROCK (Aqua-Tough) sheathing for the job. The product, which is lightweight and contains no fiberglass particles, is designed to back most exterior systems, including stone, brick, siding and EIFS. Each panel has built-in drain-age channels, allowing any moisture that invades the wall system to escape.

Plus, the sheathing had the dimensional strength to be applied to the center’s 24- in.-on-center, 18-gauge metal framing.

The owners of the center went along with the contractor’s recommendation, as did the architect, Hill Foley Rossi & Associates, Duluth, Ga. But the architect required that each exterior-finish manufacturer and installer involved with the exterior applications submit a letter acknowledging that FIBEROCK sheathing would properly back their particular system.

“Even the EIFS manufacturer had to say it would be acceptable,” Ulmer added.

All the parties agreed. The installation went smoothly. Total Dimensions used 1,200 sheets of 5/8-in.-thick, 4-ft.-by-8-ft. FIBEROCK sheathing at the center. The contractor completed all required specialty build-outs, overhangs and trims.

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