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Insulation Alternatives: Sprayed Foam Insulation

Foam insulation that is sprayed into place and then expands to fill cavities

View the ToolBase TechSpecs- Alternative Insulation Materials PDF file for an overview of this technology.

A contractor wears protective gear to spray insulation between wall studs.

Four entries in the PATH Technology Inventory describe alternatives to conventional fiberglass batt insulation for use in open vertical cavities:

  • Non-fiberglass batts
  • Sprayed foam insulation
  • Sprayed fiber insulation
  • Blown or foamed through a membrane.

This document deals with sprayed foam insulation.

Spray foam can be used as an insulating and air sealing product for residential wall and ceiling cavities. The insulation is sprayed, via special equipment, into wall cavities and expands to fill all the nooks and crannies in a wall cavity. Excess foam is scraped off the studs to form a uniform wall cavity. Spray foam insulation makes it easy to completely fill wall cavities with insulation and to perform air sealing in the same step.

There are two types of spray foam: open-cell and closed cell. The closed cell foams typically have a higher R-value than open-cell foam.

Sprayed foam insulation is applied as a liquid through a nozzle into wall, ceiling, and floor cavities where it expands to fill every nook and cranny. Because it expands into tight areas, sprayed foam is ideal for insulating steel framing and around outlets. By acting as a wind and air barrier, it often eliminates the need for separate air-tightness detailing which can increase energy efficiency and allow downsizing of the heating and cooling system equipment. Sprayed foam insulation does not shrink, sag, settle, or biodegrade.


Energy Efficiency

By acting as an air barrier, spray foam insulation provides insulation and air sealing in one step. In addition, most foam insulation products have a higher R-value per inch than fiberglass batt insulation. This increases energy efficiency by allowing downsizing of the heating and cooling system equipment.


Not-so-easy

Installation of spray foam insulation requires a skilled installer. Most products are readily available.


The installed cost for sprayed foam insulation runs about $1.25 to $2.25 per square foot, depending on wall thickness and type of foam.


Not Applicable


An approved thermal barrier, such as drywall, must cover all foam materials per section R314 of the 2003 International Residential Code.


Not Applicable


Certified insulation installers spray foam insulation in place via special equipment. As the foam dries (typically within minutes), it expands to fill the wall cavity. After it is dry, excess spray foam is trimmed from the cavity. After trimming, it is then ready for a thermal barrier covering, as required by code. Installing sprayed foam insulation typically is the last task before enclosing a wall, floor, or ceiling area. Installation is best accomplished by an experienced installer—it takes skill to completely fill a wall cavity with spray foam insulation without having a lot of overspray.


Some manufacturers provide a lifetime limited warranty. Check with manufacturer for details.


Sprayed foam materials cost more than traditional fiberglass batt insulation. However, since sprayed foam forms both an insulation and an air barrier, it can be cost competitive with batt insulation because it eliminates the steps for air-tightness detailing (such as caulking, applying housewrap and vapor barrier, and taping joints). As a result, it also reduces construction time and the number of specialized contractors.

Spray foam insulation is ideal for filling small spaces—such as window jambs, small stud bays, rim joist areas, and for sealing around electrical boxes and other penetrations—where cutting fiberglass batt insulation to fit can be difficult and labor-intensive.

Many sprayed foams are environmentally friendly. Most of them do not contain HCFCs that are harmful to Earth's ozone layer, or off gas formaldehyde—a potentially harmful volatile organic compound. Polyurethane foam insulation has about twice the R-value per inch of traditional batt insulation, making it more energy efficient in a smaller space.

Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the NAHB Research Center. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.