Spray Foam for Home Insulation

by Ryan Bazela

Air leakage is one of the leading inefficiencies of any home. Cool air is lost through leakage in the summer months, and the same happens with warm air during the winter months. Meanwhile, in the winter, cold air infiltrates interior spaces, and hot air does the same in the summer. Each of these conditions creates the need for HVAC systems to compensate for them—and that can lead to higher energy consumption and costs.

Air leakage and infiltration affect a typical home through the roof, through windows, through its foundation, and through the walls. One of the ways air leakage and infiltration can be mitigated is by properly sealing and insulating these areas with the right technologies—and spray foam is one of the most effective methods available for today’s homeowners.

In order to effectively weatherize a home using spray foam options, it’s important to understand some of the finer details. In this article, we’ll explore how air infiltrates and exfiltrates a home, how to identify leak points, and how to effectively evaluate spray foam products to meet your needs.

How Air Infiltrates a Home

In cold conditions, air tends to infiltrate through the lower portion of the house—most commonly through the basement and rim joists. That cold air then migrates up through the house and eventually escapes, or exfiltrates, through the attic. This phenomenon is known as the stack effect. In hot conditions, the stack effect occurs in reverse. Hot air infiltration occurs at the top of the house, and warmer air finds its way through the attic to the second floor. This hot air pushes cooler air to exfiltrate through the bottom of the home. In either situation, effective weatherization is dependent upon identifying the neutral pressure plane—the point at which infiltration converts to exfiltration. Identifying the neutral pressure plane allows the professional to identify and address both infiltration and exfiltration points.

One final cause of air leakage is the wind effect. Consider a 20-mph wind blowing against the side of a house. That wind finds its way both through and around the house and will pull air from around and through the house, creating leakage. Rather than through joists or attics, in this case, a home may experience leaks via electrical sockets or other gaps in the building envelope. This phenomenon, in combination with the stack effect, can add up to significant leakage and efficiency loss.

Low-Pressure Spray Polyurethane Foam (SPF)

Identifying Leak Points

The next step in weatherizing your home is to identify leak points. Remember that the most common leak points occur at the adjoinment of different building materials. Here, breaks in the building envelope are causing the leakage.

In addressing such problems, your first priority should be the home’s attic. In most cases, this is where a home sees the most significant leaks and where heat escapes during cold weather. You should look for any seams throughout the attic perimeter. Knee walls are a common point of transmission.

Your second priority should be the basement and crawl spaces. Addressing leaks in these areas helps to eliminate key sources of air infiltration. One of the most common sources of infiltration here are the rim joists—properly sealing rim joists will be highly effective in improving the building envelope.

Finally, you’ll want to address leakage throughout the remainder of the building envelope. Some common areas include the undersides of any bay windows or cantilevered floors; awnings above bay windows; the space around windows themselves; and within the interior of the home itself such as light fixtures and electrical sockets.

These visual inspections can be effective, but more advanced diagnostic methods performed by qualified professionals can be applied to better determine leak points. For example, a blower door test will depressurize a home and simulate adverse weather conditions. Air exchanges can be measured per hour—the rate at which air is completely replaced and replenished on an hourly basis. Using the same method following the addressing of leak points can also validate the weatherization work that has been performed. Infrared imaging can also help identify leak points by visualizing temperature differences at critical points throughout the building envelope. These methods can also help determine areas in your home that need more insulation.

Low-Pressure Spray Polyurethane Foam (SPF)

Spray Foam: An Effective Tool for Weatherization

After leaks have been identified, they must be addressed. One of the most effective methods for doing so is by using low-pressure spray polyurethane foam. Air sealing with foam typically has the highest and quickest ROI of all air sealing methods compared with traditional insulation and sealing methods. A few reasons why include:

·       Foam is highly effective at stopping air infiltration, in part because foam’s expanding properties can more effectively fill gaps, particularly those with irregular shapes or that are in hard-to-reach areas.

·       When installed properly, foam also creates an effective moisture barrier, which can have a dramatic impact on mold and mildew reduction.

·       Foam can also help stop the transmission of noise through leak spots.

·       Spray foams are convenient for smaller retrofit jobs and can be easily scaled for larger projects.

·       Foam provides the highest R value (a measure of thermal resistance) of any insulating material.

Low-pressure polyurethane foam systems can be used to air seal and insulate small to mid-size areas with low equipment costs. Low-pressure polyurethane foam chemicals are combined in the nozzle chamber and sprayed at room temperatures at a significantly lower pressure. The output of 5–7 lbs. per minute decreases the chemical emissions, allowing for a faster home and building reentry time.

Under the low-pressure polyurethane foam category there are three subcategories of foam based on application method: spray polyurethane foam (SPF), pour-in-place polyurethane foam (PIP), and one-component polyurethane foam sealants and adhesives (OCF).

• Low-pressure spray polyurethane foam is a chemically cured, two-component system designed to fill and insulate large voids and surfaces. This delivers excellent adhesion properties and creates a continuous air barrier completing the building envelope, which results in improved indoor air quality and lower heating and cooling costs.

• Low-pressure pour-in-place polyurethane foam is a chemically cured, two-component system specifically designed for filling cavities, molds, fixtures, or holes where a slower curing and expanding polyurethane foam is required.

• Low-pressure one-component polyurethane foam sealants and adhesives are pre-reacted in the can and undergo further reaction with ambient moisture at the time of application. One-component polyurethane foam sealants and adhesives are generally used for smaller-bead applications.

  
  

When choosing a product, however, it is important to be sure that your selection meets the criteria for its intended application. For example, consumers may encounter spray foam products that are advertised for use as a sealant, as insulation, or in some cases, both. But sealants and insulation must meet specific codes, testing requirements, and specifications including (but not limited to) U.S. building codes, FTC labeling or testing requirements, OSHA regulations for hazard reporting, and PUR product standards.

Also available is medium density, pour-in-place (PIP) polyurethane foam designed designed to fill cavities, molds, holes and voids of various sizes. PIP foam is formulated to decrease vibrations, deaden sound and provide buoyancy (for flotation devices, etc.).

Safe Deployment of Spray Foams

All polyurethane foam products contain diisocyanates, which are chemicals that may cause sensitization by inhalation and skin contact. For this reason, when using any low-pressure polyurethane foam, it is recommended to wear proper personal protective equipment (PPE), including safety glasses or goggles, long-sleeved shirts and pants, arm gauntlets, and nitrile gloves.

It is also important for the space to be well ventilated to avoid excessive inhalation, but that is not always possible when working in potentially tight spaces. In such instances, wearing a respirator is necessary. It can be helpful to establish air flow in the space to replenish air and exhaust the vapors outside of the structure. A fan with enough power to provide such ventilation can typically be purchased at a local retail home improvement center or hardware store.

Finally, it is critical for users to read a product’s safety data sheet (SDS) and technical data sheet (TDS) for proper operating procedures, product stewardship guidelines (including how to dispose of empty cannisters), and other critical information. These items should always be available from the foam supplier; if they aren’t, it may be a sign of a misleading product.  

When in doubt, effective deployment of spray foam can be conducted by a professional.

Spray foams and sealants can be a highly effective means of insulating homes and sealing cracks and gaps where air can escape or infiltrate. Performed properly, deployment of these technologies can help improve a home’s comfort, energy efficiency, indoor air quality, and more.

About the author: Ryan Bazela is Sales Director for Insulation Products, ICP Building Solutions Group. To learn more about spray foam insulation and how to seize the benefits, visit www.HandiFoam.com.

*All photography appears courtesy of HandiFoam