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DCD Design Cost Data

Code Compliance in a Single Exterior Wall Panel

Posted: August 1, 2017 | Project Management

By Richard Chase and Dan Johnson

NFPA 285 exterior wall fire resistant directives and the advent of WSEC (Washington State Energy Code) “Continuous Insulation” now require no thermal breaks across structural members. Because of these developments, the design community was charged with the responsibility of identifying a variety of independent products and materials and combining them into a cohesive exterior cladding that provides performance, durability, and service life at a reasonable cost to their clients.

Were it not for the historical complications inherent when using EIFS (exterior insulated finish systems), it would be a logical candidate for compliance with both NFPA 285 and WSEC. But many building owners, contractors, and architects were skeptical – particularly with an assembly perceived to have difficulties.

Introducing ROK-ON™ Structural Insulated Sheathing

Then along came a brand new “Structural Insulated Sheathing” product called ROK-ON™ SIS. New Federal mandates for both energy and fire codes now require changes in how buildings are constructed. Compliance can necessitate adding as many as seven products to the external configuration beyond the framing. Imagine the added expense and added time in the construction cycle.

Developed by ROK-ON™ Building Systems, ROK-ON™ SIS provides a high-performance wall insulation system designed to meet the new energy and fire codes in one easy step. The system is centered around a 2.75" panel that has a 2" core of rigid insulation surrounded by a layer of fiberglass-reinforced ceramic cement board.

The typical panel is R 10.5, and is attached directly to framing as the structural sheathing. The system can accommodate most architectural finishes, but is particularly well-suited for direct applications of Stuc-O-Flex. It can be finished directly, without additional layers needed to protect typical substrates like gypsum, plywood, or OSB.

The unique combination of the physical properties of ROK-ON™ with its fiberglass-reinforced ceramic sheathing increases performance while removing the risk of rot, mold, or fire damage. And ROK-ON™ panels eliminate the threat of liability associated with common EIFS assemblies.

These robust panels will not burn, delaminate, rot, mold, or deteriorate. Joints are glue-sprayed and sealed using a fiberglass mesh. Each joint is triple sealed – providing substantial redundancy against failure to the elements.

With a lasting finished exterior of Stuc-O-Flex, these ROK-ON™ panels have been used throughout the U.S, Canada, and Mexico in residential and large commercial applications for both new construction and retrofit. They can bolt or screw directly to wood, metal, or concrete, and be installed and finished in three easy steps without any special tools, trades, or fasteners. The panel’s strength and impact resistance makes it ideal for use in prefabrication.

A Collaborative Approach between Two Trusted Companies

Stuc-O-Flex International, Inc. is known as a leader in the field of formulating, testing, and manufacturing vertical wall products. Thirty years ago, they introduced the first breathable elastomeric acrylic finish (the industry’s first stretchable finish for stucco and EIFS), minimizing the likelihood of cracks.

At that time, Stuc-O-Flex was one of approximately 30 companies enjoying the expanding market opportunities for exterior insulation and finish systems. Developed in Europe for use on masonry walls, EIFS were a hot commodity in the U.S. during the oil embargo of the 1970s. However, there was a problem: American installations involved framed walls with sheathing, not solid masonry.

In the mid-1990s, EIFS came under increased scrutiny when moisture penetration (generally at the interface with adjacent materials) became trapped behind the insulation. This caused deterioration of sheathing and some of the structural framing.

Use of EIFS declined dramatically as litigations mounted, and it wasn't long before architects and builders chose other options. The insurance industry's decision to raise premiums – in some cases by 500% – on EIFS-clad structures was the final blow.

In an effort to mitigate moisture-related problems associated with EIFS, Stuc-O-Flex developed the industry’s first rainscreen drainage mats, marketed under the trade name “Waterway.” Stuc-O-Flex has since sold over 60 million square feet to alleviate water penetration issues and waterproof buildings.

To keep up with changing market conditions, Stuc-O-Flex also designed the first drainable rainscreen stucco assembly. With a continued desire and demand for the appearance and aesthetics of EIFS and/or traditional plaster, this rainscreen stucco configuration was intriguing to the architectural and design communities. With millions of feet of EIFS retrofit and repair necessary, this design became the basis and scope of work to repair and resolve construction defect litigation by many consulting engineering firms.

Using ROK-ON™ SIS panels with a Stuc-O-Flex applied exterior has proven to be a time-and-money saving technique that provides continuous insulation as well as moisture prevention in practically any type of environment. The collaboration of these two companies to present this unique exterior shell offers many benefits and cost savings to builders and designers keen to take advantage of innovation and technology.

For more information, contact: Richard Chase @ or Dan Johnson @