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Is Spray Polyurethane Foam A Good Air Sealant?

12/22/2014 | by Clarke Berdan II

Spray Polyurethane Foam (SPF) entered the residential building industry as both an insulation and air-sealing solution. Air sealing, along with proper thermal insulation, is an important part of delivering a comfortable, durable, healthy and energy efficient home. Recent advancements in building science, along with Owens Corning's groundbreaking AIR SEALING STUDY, give us a better understanding of the impact air leakage has on a home's performance.

We now know that most air leakage occurs where components are joined, not in framing cavities where most insulation is installed. ExtensiveRESEARCH shows that once a building is sealed, R-value, not insulation type, is all that matters for thermal performance.₁What does this mean in practical terms?

Let's compare the thermal performance and air sealing performance of spray polyurethane foam with fiberglass insulation products and air-sealant.

THERMAL PERFORMANCE
Installed in a properly sealed building, SPF can deliver intended R-value and thermal performance.₁ However, shrinkage occurs when SPF has been incorrectly manufactured at the job site and/or installed while framing lumber is wet – a real-world condition in the new home construction process. This shrinkage creates gaps between the insulation and framing members, compromising thermal performance and increasing the potential for thermal convection looping and moisture damage.₂

SPF advocates often claim credit for air sealing as a way to offset insulating to the full R-value. However, building science does not support these claims.₁

Compare this to fiberglass. The quality of fiberglass products is managed during manufacture in a controlled environment with frequent quality control checks. And fiberglass insulation is easily inspected for installed thermal performance.

AIR SEALING
Spray polyurethane foam is often marketed as a dual solution that can provide air sealing and insulation. However, it leaves many critical sources of air leaks unsealed and therefore is not a complete air-sealing solution.₁

In contrast, Owens Corning™ EnergyComplete® Sealant is an air-sealing solution that creates a flexible gasket to reduce both air leakage and noise penetration. EnergyComplete® Sealant meets R-value targets while EcoTouch® Insulation seals the most critical air leakage points in a home.₃

SEPARATE CONCERNS
Owens Corning understands that insulation and air sealing are two separate building envelope concerns that require dedicated solutions. SPF is only a partial solution that adds cost.

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SOURCES:
1. HTTP://WWW.BUILDINGSCIENCE.COM/DOCUMENTS/SPECIAL/CONTENT/THERMAL-METRIC/BSCTHERMALMETRICSUMMARYREPORT_20131021.PDF
2. "Spray Polyurethane Foam Uses in Modern Building Construction Applications and Limitations: The perspective of a system failure investigator." Build Boston, 2010. Ned Lyon, Simpson Gumpertz & Heger.

3.HTTP://OCENERGYCOMPLETE.COM/DOCS/LITERATURE/ENERGYCOMPLETE%20WHITE%20PAPER%20BROCHURE.PDF

Related Tags: Thermal | Performance | Health | Comfort/Livability | Durability/Enduring Value