SPRAY FOAM INSULATION

The following information has been assembled in an effort to explain and clarify the sometimes complicated concepts in Building Science. Residential construction methods have been generally consistent for decades. As new technology develops, the construction industry is typically slow to keep up while design and construction professionals gain experience and confidence in incorporating new products into the complicated composite we know as a “home”.

Homes have historically been built to intentionally allow structures to “breathe” for fear of trapping moisture. Uncontrolled moisture presents a clear concern for the longevity of most building materials. The “breathability” alleviates the concern for reasonable amounts of unmanaged moisture but unfortunately does not control the inflow of airborne pollutants and allergens and the loss of conditioned air. This lack of control compromises the indoor air quality as well as significantly increases consumer costs through energy loss.

Spray foam technology eliminates the aforementioned issues by raising the standards of functionality and design for both residential and commercial construction. Spray polyurethane foam has been commercially available for over half a century and is now being accepted as a mainstream solution in retrofit construction for both residential and commercial construction.

AIR BARRIER MATERIALS

APPROACH
Air barriers created by the use of spray polyurethane foam should be the primary strategy utilized when designing high-performance roof or attic assemblies. Spray polyurethane foam provides:

• Reduced infiltration and exfiltration of both moisture and air
• Added rack and shear strength to the assembly
• Superior insulation properties
• Controlled thermal loading of appliances and ductwork located in the space

AREAS OF AIR MOVEMENT

Sealing and insulating the “envelope” or “shell” of your home – its outer walls, ceiling, windows, doors, and floors – is often the most cost-effective way to improve energy efficiency and comfort.

AIR BARRIER MATERIALS SHOULD BE:

• Impermeable to air flow
• Continuous over the entire building envelope
• Able to withstand the forces that may act on them during and after construction
• Durable over the expected lifetime of the building

In order to design and build safe, healthy, durable, and economical buildings, airflow must be controlled. Uncontrolled airflow carries moisture that impacts a material’s long-term performance (serviceability), structural integrity (durability), indoor air quality (distribution of pollutants and location of microbial reservoirs), and thermal energy performance. One of the key strategies in the control of airflow is the use of air barriers.

Air barriers are intended to resist the air pressure variations that act on them. Spray foam systems can serve as a successful air barrier, either externally applied over structural elements (closed-cell spray foam) or internally applied (closed and/or open-cell spray foam) within cavity systems at the proper thickness.

Air barrier systems keep outside air out of the building enclosure or inside air from escaping the building enclosure, depending on climate or configuration. Sometimes, air barrier systems do both. Air barriers can be located anywhere in the building envelope.

In cold climates, interior air barriers control the exfiltration of the interior, often moisture-laden, air whereas exterior air barrier systems control the infiltration of exterior air and prevent wind-washing through cavity insulation systems.

INSULATION MEASURING THE VALUE

Heat loss or gain can occur through a building envelope by three primary mechanisms: conduction, convection, and radiation. Three secondary mechanisms that influence the performance of insulation are air finfiltration, air intrusion, and moisture accumulation. Spray polyurethane foam effectively controls the three primary and three secondary mechanisms of heat transfer, resulting in insulation efficiencies well beyond those suggest by its high R-value alone.

CONDUCTION

R-Value is a well-publicized “status” to reflect insulation value to consumers. R-Value only measures conduction or the material’s ability to resist heat loss or gain. It is derived by taking the “k” value, determined by using an ASTM test method, and dividing it into the number one. The “k” value test is the actual measurement of heat transferred through a specific material. The test favors fiber insulation materials – fiberglass, rock wool, and cellulose fiber as the test does not account for air movement (wind) or moisture (water vapor). Zero wind and zero moisture are not real-world conditions.

Spray Foam Insulation: The predominant heat transfer mechanism for spray foam is conduction. However, because of the polymer matrix forming the cells is a poor conductor of heat, spray polyurethane foam has a very high R-Value and effectively blocks heat transfer by conduction.

CONVECTION

Convective heat transfer occurs when a liquid or vapors come in contact with a material of a different temperature. Within a stud wall cavity, “convective loops” will occur when the exterior and interior temperatures are different. For example, if the interior is warm and exterior cold, air within the cavity in contact with the exterior wall will cool, becoming denser, and flow downward. On the other hand, the air in contact with the interior wall warm, becoming less dense, and rise. Air rising and falling within the wall cavity forms a “loop” which transfers heat from the warm wall to the cold wall. The result is increased heat loss/gain and costly energy bills. By stopping the air movement, convective heat loss will cease.

Spray Foam Insulation: Spray foam eliminates air movement within the insulation material eliminating convection as a heat transfer mechanism within the insulation mass.

RADIATION

Radiation is the transfer of heat from one object to another by means of electromagnetic waves. Radiative heat transfer does not require that objects be in contact. Radiative heat transfer occurs in the void of space.

Spray Foam Insulation: Heat transfer by radiation is effectively blocked by spray foam because of the cell structure. Heat can transfer by radiation across each cell. However, because the cells are at basically the same temperature, heat transfer by radiation is non-existent. Additionally, the building interior walls insulation with spray foam tend to be nearly the same temperature as the room. Therefore radiant heat variances to an occupant are minimal leading to great indoor comfort.

AIR INFILTRATION

Air Infiltration transfer heat by the gross flow of air between the exterior and the interior. The primary force behind air infiltration is the air pressure difference between the exterior and the interior. Air pressure differences can be caused by wind or stack effect.

Spray Foam Insulation: The bonding of spray foam plus the expansion of the material in place will create a total seal. Spray foam is one of the only insulation materials that will fill in corners, the cripples, the double studs, bottom plates, top plates, etc.

AIR INTRUSION

Unlike air infiltration, wherein air moves from the exterior to the interior, air intrusion occurs when air enters the insulation from the exterior and exits back to the exterior. Air intrusion is also called “wind wash.” There is no drafting of air to the interior of the building but the thermal gradient of the insulation is disrupted. In effect, air intrusion introduces forced convection into the building envelope (wall, ceiling, etc.). Air intrusion can substantially undermine the effective R-Value of conventional insulations and can occur independently of air infiltration. Like infiltration, house wraps are traditionally used with conventional insulation systems in an attempt to reduce air intrusion. Vapor retarders installed on the interior side of the building envelope will not affect air intrusion.

Spray Foam Insulation: The adhesion of spray foam insulation to most building materials creates a total seal for the building envelope. Stopping air intrusion is one of spray polyurethane foam’s greats assets.

MOISTURE ACCUMULATION

Insulation is an important component in a moisture management system. Air infiltration and exfiltration, within a structure, contributes to approximately 99% of moisture intrusion. Moisture accumulation within insulation materials will reduce the insulations R-Value, contributing to heat loss/gain. Moisture accumulation can be controlled with effective air barriers, vapor retarders or “flow-through” designs (which allows moisture transfer without condensation).

Spray Foam Insulation: Spray foam stops moisture accumulation by reducing air infiltration and air intrusion. In addition, closed-cell spray polyurethane foam retards both heat transfer and water vapor transfer, making it an ideal material for use with flow-through designed buildings assemblies.

ABOUT CLOSED-CELL INSULATION

Closed-cell spray foam insulation is one of the most efficient insulation materials commercially available, with aged R-Values at almost 7.0 per inch.

The description “closed-cell” comes from the cell structure of the finished insulation material. One cubic inch of polyurethane foam insulation contains millions of tiny plastic closed cells filled with a non-ozone depleting blowing agent. The blowing agent is captured within the cells which contributes to highly efficient insulating properties. In addition, closed-cell foam provides an inherent air barrier with low moisture vapor permeability and excellent resistance to water. The density for closed-cell spray foam is approximately two pounds per cubic foot. The medium density foam provides sheer and racking strength to wall assemblies in building applications.

Closed-cell spray foam insulation systems, when properly installed, deliver energy savings of up to 40%.

Small imperfections in the building envelope (holes, cracks, gaps) not properly sealed will eventually lead to poor building performance or worse, moisture accumulation, allergen/pathogen growth, and very possibly structural failure. The solid nature and sealing capability of closed-cell spray foam inhibit moisture-driven elements. Two inches of closed-cell spray polyurethane foam insulation will minimize air infiltration, exfiltration, convection and conduction, and control solar driven moisture in the building envelope.

FEMA Technical Bulletin 2-93

• “Closed-cell” is the only type of insulation classified as an “acceptable flood-resistant material” by FEMA.
• “Flood-resistant material” is defined as any building material capable of withstanding directed and prolonged contact with floodwaters without sustaining significant damage.
• Batt or blanket insulation types and all other insulation types are classified as “unacceptable”.

FEMA Technical Bulletin 2-93 "Flood-Resistant Materials Requirements for Buildings located in Special Flood Hazard Areas in accordance with the National Flood Insurance Program.

(1) ASTM-E96, 1 Perm or less is required to qualify as a Class II vapor retarder

ABOUT OPEN-CELL INSULATION

Open-cell spray foam insulation is spray-applied, half pound density, non-structural, thermal insulation material used in wall cavities, floor assemblies, ceiling assemblies, and attic applications. Open-cell foam insulation is a performance upgrade over conventional insulation that leads to energy efficiency, improved occupant comfort, a cleaner indoor environment, and great noise reduction for building/homeowners.

Building envelopes with increased insulation levels are becoming standard practice. Consumers are increasingly involved in the selection of green building products due to rising energy costs.

Open-cell spray foam technology is a cost-effective solution to improve the energy efficiency of a building. The material expands 120 times its initial volume and fills cavities of any shape providing a continuous, protective air barrier that helps to minimize air leakage and air intrusion.

Open-cell VS Closed Cell Spray Insulation Comparison

¹ For actual performance data on a specific SPF product consult the manufacturer’s technical data sheet.
² As designated by the International Code Council in Acceptance Criteria AC377
³ Flammability ratings do not represent actual performance in a fire situation. Class 2 is required in most residential applications. Class 1 is required in commercial buildings and some residential applications.
⁴ Classified as “Acceptable Flood Resistant Material” by FEMA, Tech Bulletin 29-3. Fiberglass batt and blanket insulation are classified “Unacceptable”.

Spray Polyurethane Foam Insulation

FEATURES

BENEFITS

Spray Applied

• Seals cracks and crevices
• Insulates hard to reach areas
• Quick and easy installation by a Qualified Applicator
• Self-adhered seamless layer of insulation
• Conforms to any architectural design

Minimize Air Infiltration/Exfiltration

• Keeps conditioned air where it should be – inside the building
• Helps eliminate drafts and provides for comfortable interiors

Excellent Adhesion

• Adheres to most building materials
• No fasteners required

Light Weight

• A high degree of strength-to-weight ratio
• Adds little weight to ceiling or roof areas

Safe

• Meets Class 1 building requirements
• No off-gassing after fully cured

Open-Cell  Spray Foam

FEATURES

BENEFITS

High Insulation Value

• Performs in hot as well as cold climates

Rigid

• Will not settle or shrink

Moisture Resistant

• Helps protect against mold and mildew

Closed-Cell  Spray Foam

FEATURES

BENEFITS

High Insulation Value

• High R-Value allows more insulation in less space (2” x 4”s instead of 2”x 6”s) – cost savings in stud size reduction
• Performs in hot as well as cold temperatures

Rigid

• Will not settle or shrink
• Adds structural strength

Moisture Resistant

• Inhibits moisture driven elements due to its closed-cell structure
• Helps protect against mold and mildew