Spray-on latex sealants: A new tool for air barriers

Owens Corning's EnergyComplete latex foam sealant is applied with a paint sprayer, goes on quickly, and remains flexible after curing.

Build tight, ventilate right is the building science mantra. Spray-on latex sealants provide a new tool for airtight construction.

Last month I watched a demonstration of Owens Corning's "EnergyComplete Air Infiltration Barrier and Flexible Seal Technology" on the expo floor at the Northeast Sustainable Energy Association (NESEA) BuildingEnergy11 conference. I was intrigued, so I contacted the company for a bit more information.

According to Matt Girand, Director of Products and Programs at Owens Corning, "We looked at our core product, fiberglass insulation, and recognized the conversation was shifting away from just R-value to total home performance," Girand said. "We wanted to address both air infiltration and thermal performance."

In other words, Owens Corning has seen the reputation for its fiberglass batts weaken because they don't contribute to the building's air barrier, while competing products like cellulose and foam both insulate and contribute to air sealing.

A new tool for stopping air infiltration

Preventing air infiltration in a new building usually requires caulk, gaskets, or installation of spray polyurethane foam (SPF), or some combination of measures. Each of these has its downsides and weak points. It takes a lot of time and personnel to caulk a 2500 square-foot home; it is easy to miss small cracks; the caulk might not adhere properly; and caulk can deteriorate with age, allowing air to leak through as the house ages. And once the wall is sealed behind insulation and drywall, fixing any leaks is not easy or cheap.

SPF is not perfect either. It's expensive; closed cell versions usually contain blowing agents with high global warming potential; SPF can separate from the wood as framing expands and contracts; and it contains toxic isocyanates, so other trades have to leave the area during application, delaying construction.

Fiberglass manufacturers confronting air infiltration

EnergyComplete is a two-part, flexible, expanding latex foam sealant that is applied with a specially designed Graco paint sprayer. It is not meant as insulation, though it has an R-value of 3.2. In the demonstration I watched, it went on fast--much faster than caulk--and fully covered the gaps (up to 3/8 inch) in the mock wall assembly.

The two parts, which are red and white, come in separate four-gallon pails and are mixed as they pass through the "proportioner" and spray gun where they react to create the final foam, which comes out in the company's trademark pink color. The foam penetrates cracks where it expands to fully seal potential leaks, and the latex formula is flexible when cured and stays adhered as the wood expands and contracts. EnergyComplete can be installed down to 20°F and takes about 20 minutes to set before insulation can be installed. If it's colder than that, the house might need to be heated, similar to SPF installation.

Improving the performance of fiberglass insulation systems

Girand said that one builder using the entire EnergyComplete system (fiberglass and sealant) on a new home has tested at less than 1.5 air exchanges per hour at 50 pascals (ACH50), measured using a blower door test, but 3 ACH50 has been the norm. For comparison, Energy Star 3.0 requires 4 ACH50 but Passivhaus standards are a stingy 0.6 ACH50.

According to Girand, one area that EnergyComplete excels is sealing the base plate, where caulking can be a challenge because of accessibility, dust, and other factors. But the EnergyComplete spray gun system blows away dust and debris from the surface before the foam hits it. Then the foam flows into the crack and expands. Girand says that after curing drywall can be applied over the top of it, so when sprayed along the top plate it creates a gasket and tight seal, so there is no need to return to the jobsite after the drywall is installed to seal that connection.

The sealant is sold as part of a complete Owens Corning system, so you are locked into using the company's fiberglass blown-in loose fill or batt insulation products. Nope, you can't use it with cellulose or other insulation. But Owens Corning has released a formaldehyde-free version of its batt insulation called EcoTouch, which uses a bio-based binder. This combination should keep the indoor emissions to a minimum.

Knauf's EcoSeal is not a foam but is applied with a standard paint spray rig.

Low VOC emissions

EnergyComplete is an open-cell, water-borne, non-flammable (flame spread <25, smoke developed <50) latex foam. It contains no toxic isocyanates. It is Greenguard Children & Schools certified for low emissions (VOC content of 39.4 grams per liter), so trades can continue to work onsite during application and installers do not need breathing equipment as with SPF. According to Girand, "We recommend, goggles, a dust mask, and maybe a long-sleeve shirt because it is something that is sprayed, but there are no concerns around the emissions of the product." The material cleans up with soap and water if you get to it before it cures. After that you have to use the company's special solvent.

Sold through contractors

Since the EnergyComplete system was launched back in June 2009 it has flown somewhat under the radar terms of its rollout. Sold through contractors trained by Owens Corning, the company first focused on small homebuilders but has now attracted larger builders, including Lennar Homes in Texas, which is using the EnergyComplete system in all of its Texas homes.

The problem of proprietary ingredients.

Companies want to keep trade secrets to themselves, which is understandable from a business model, but this secrecy is frustrating for those of us trying to determine if a product is safe. Unfortunately, most of the ingredients in the EnergyComplete system are proprietary, so it is difficult to give a full environmental assessment of the product. The company is weighing how much they can tell me for a more in-depth review in Environmental Building News. Stay tuned!

As a latex foam, EnergyComplete is a unique system, but Knauf also offers a water-based elastomeric sealant named EcoSeal . I'll be looking at both of these systems in a little more detail for that review. In the meantime, if you've had any experience with the system, let us know.

Brent Ehrlich is the products editor at BuildingGreen, Inc. See more on Knauf's EcoSeal in the GreenSpec GuideSee more on Owens Corning's EnergyComplete in the GreenSpec Guide