June 2012

Volume 21, Number 6

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Green Topics

Tremco: Getting the Devil Out of Air and Water Details

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This rendering shows how each component of the Engineered Transition Assembly works toward air- and water-barrier continuity. At the product level, the key to the Tremco ETA system is compatibility of materials. But at the design and construction level, the performance of this system is in the process, which includes quality assurance elements, custom review by Tremco of all wall assembly details, and performance testing of the air and water barriers.

Photo: Tremco

By Peter Yost and Jennifer Atlee

Designing, specifying, and constructing high-performance commercial building assemblies is a tall order. Lining up and integrating all of the components for continuous air and water barriers can be maddening. And whose job is this? It’s actually a chain of responsibility: architect, specifier, general contractor—and, finally, all the trades.

Where do the manufacturers of all the components fit in? They just make and sell stuff and then all the building professionals get to work it out, right? Not always—and certainly not if Tremco has anything to say about it. Tremco has patented and commercialized its Proglaze Engineered Transition Assembly (ETA) System as an integrated whole of compatible sealants, membranes, primers, and flashings (all its own products) with both insulation and sheathings (other manufacturers').

But the system is not just about products; Tremco has done extensive research and development to ensure compatibility. The system involves comprehensive details, a quality assurance program, and a performance warranty on the air and water barriers in any building—a first for the industry.

The most interesting aspect of the ETA system is the development of final details in a custom collaboration between the design firm and Tremco. “While we patented the ETA system, its employment on each project is through custom details,” says Mike Sebold, business leader for building envelope solutions at Tremco Commercial Sealants & Waterproofing. To be clear, Tremco does not stamp any drawings, but its team is substantially involved in the development of all the wall details—even going so far as to offer performance tests for each and every project according to ASTM E2357 (Standard Test Method for Determining Air Leakage of Air Barrier Assemblies). While Tremco does not require the performance testing on a wall mock-up, it recommends it. “We can offer the warranty without the performance testing, but we won’t without final approval of the details,” says Sebold. “And we are finding that the trend to value-engineer performance testing of mock-ups out of projects is starting to reverse.”

It’s not that hard to design the field of a wall. It’s the connections, particularly of dissimilar materials, that are hard; this is where many commercial exterior wall systems fail. “With Tremco’s ETA, you won’t see or hear the phrase ‘connection by others,’” says Sebold. “It’s the connections, corners, and transitions that ETA addresses and excels at.”

You won’t be surprised to hear that, per lineal foot, the Tremco ETA system is “expensive” (more like $15 for ETA compared to around $5 per lineal foot for the standard, two-stage sealant approach). But Sebold is quick to point out, “The ETA system is a classic, high-performance, green technology. If we are brought in during design development for a project where a high-performance, durable building is the stated goal, then the ETA system is just a completely integral part of the value proposition.”

Wagdy Anis, AIA, a principal at Wiss, Janney, Ellstner Associates, was an early user of the ETA system and has worked with it for more than a decade. “Tremco has embraced systems thinking and building science,” states Anis.

In one of the first projects using the Tremco ETA system, the West Tower at the Children’s Hospital of Wisconsin in Milwaukee, Anis worked with Brian Stroik, corporate quality manager for The Boldt Company. “It’s a fantastic system,” says Stroik, who relates that in early testing, “when they pushed the window assembly to failure, the jamb anchors pulled out of the jamb, and the Tremco silicone sheet and sealant held firm—really impressive.”

Stroik continues, “The Tremco ETA system is durable and flexible, two of the most important properties for those continuous water and air barriers. We use the ETA system on the majority of our projects that are looking for a 50- to 100-year life cycle.” Stroik readily admits that the Tremco ETA system costs more to install, but he says, “owners are looking for and understand the need to install products that increase the energy savings potential and service life of a building.”

EBN investigated whether the performance of ETA comes at a cost in health or environmental impacts. All the products in the ETA system have Greenguard Children & Schools certification for emissions. According to Tremco sustainability manager Michael Schmeida, Tremco’s green chemistry team has identified a target list of chemicals of concern that they have been seeking to systematically eliminate.

In addition to the ExoAir air barrier to which it adheres, the ETA system is composed of four components:

• silicone rubber extrusion and corners;

• an alodine-finished extruded aluminum adaptor;

• Tremco 440 Tape, which is a 100% solid polyisobutylene cross-linked butyl performance sealant that acts as a temporary hold while mechanical fasteners are installed (as well as a secondary air and water seal);

• and Spectrem 1 silicone sealant—a single-component, neutral-curing silicone.

According to Schmeida, Tremco has eliminated phthalates, which are typically used as plasticizers, from its silicone rubber. From what is disclosed on the tape and sealant material safety data sheets (MSDS), the material constituents appear relatively low in known health hazards. The exceptions to this are the phthalate DIDP, which is used in some tints of Spectrem 1 silicone sealant, and also polydimethylsiloxane, trimethyl endcap, which, according to the Pharos product screening tool, is listed by the Canadian government—but not by other groups—as a persistent, bioaccumulative toxic chemical (PBT). (The Canadian list uses computer modeling to identify potential PBTs, not only chemicals proven through testing to be PBTs.) According to Schmeida, this chemical is a reactant that is not found in the cured product. Both the tape and the sealant also include ingredients that are proprietary trade secrets.

Adhesives and sealants frequently include both trade-secret ingredients and hazards that are not disclosed beyond the basic requirements for the MSDS. While Tremco products are not free of hazards, they may contain fewer hazards than other products. With Greenguard Children & Schools certification and Tremco’s efforts to reduce toxicity at the product formulation level, the system stands out for its low-hazard profile as well as for its unique performance benefits.

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