The debate between using Spray Polyurethane Foam (SPF) insulation versus more traditional methods of insulation is an interesting topic in the building industry today. There are many different factors for a homeowner to consider when considering SPF as an option. Experts that advocate for the use of SPF will point out the great R-Value and air tightness that can be achieved by using SPF products. Opponents will bring to light the potential health problems that it could cause installers and end users. The fact is there are many pros and cons to using this product. The purpose of this blog is not to sway homeowners in either direction; there is certainly plenty of subjective literature arguing in both directions. Instead, the intent is to provide the necessary facts and information that will allow homeowners to make informed decisions on whether or not to consider the use of SPF for their individual projects.History Before outlining the pros and cons of SPF use, just a bit on the history and science behind the products: SPF is viewed in the building industry as a relatively new product. The history of Foam use in the United States Building Industry dates back to the late 1960's as a roofing material, it was used primarily in this capacity for the next few decades. It was not until the 1990's when open cell foam began being used to insulate interior wall cavities. Today, SPF is being used in many different capacities throughout the building industry.ScienceWithout getting into the detailed chemical equations of SPF and its parts, it is important to understand the basic components that go into a product before making an informed decision on whether or not to use it in a home. SPF is generally grouped into two categories: open cell (low density) and closed cell (medium or high density). Open cell foam contains air spaces, while closed cell foam has pockets filled with gas [3].SPF is comprised of 2 parts; part "A" is the Isocyanate component. Isocyanate (typically MDI) is a highly reactive organic chemical compound [1]. Part "B" is the resin component, it contains a polyol, catalyst, blowing agent, fire retardant, and surface active agents (surfactants) [1]. The two parts are contained separately until they are applied. In typical high pressure applications, the two parts are stored in drums; they then travel through a "proportioner," which dispenses the two parts to a heated tube at a controlled ratio. The parts are finally mixed together and dispensed at the spray gun. This mixture creates an exothermic reaction that produces high heat during curing, for this reason; SPF is typically applied in layers. The ratio of the two components is critical to the successful application of the foam; any deviation from the manufacturer's recommendation could cause the foam to cure incorrectly. This incorrect foam will not function as desired, and also could pose health risks if left un-cured.The ProsNow, the pros of SPF use: First, SPF has an extremely high R-Value. Open cell is comparable to other insulations at R3.5 per inch, but properly installed closed cell comes in at about R6 per inch. Increased R-Values mean decreased heating and cooling costs, and also helps homes comply with new, more stringent energy codes. Second, SPF eliminates air infiltration and assists in controlling moisture and condensation, making it an effective weapon in the battle against mold and generally increasing indoor air quality. Third: SPF maintains its effectiveness in low and high temperatures, where other insulators may be less effective in extreme climates. There are many other benefits of using SPF, but these are the most important issues to most potential home owners.The ConsThe cons: First and foremost, SPF is comprised of chemicals that if installed incorrectly or left un-cured could pose health risks, most commonly asthma - please note: research indicates that the most danger is to the SPF installers, and not the eventual occupants [2]. It is important to also state that properly cured SPF is considered relatively inert [1]. Second, long term concerns for SPF come when considering future building renovations or remodels. Any cutting, grinding, or heating of cured SPF could lead to Isocyanate exposure. Lastly, on a project with a strict budget, cost may be a factor in the choice of insulation. The up front cost to using SPF compared to using a fiberglass batt or other traditional form of insulation can be significant, as much as two or three times greater. The cost of installation can be offset with decreased energy costs throughout the life of the home, but as always, is something to consider.Bottom LineIf the decision is made to use SPF, precautions should be put in place to ensure a quality installation. The subcontractor should be reputable, with documented history and experience with SPF installations. There are many third party testing agencies available for hire that will be able to confirm proper applications, density, and curing. Knowing all of the facts about any product that will be used in the most important investment of most people's life is the first step in making a proper decision. In the end, it is always the homeowner's choice whether or not to use SPF or any other building material on their project.[1] Spray Polyurethane Foam Alliance: www.sprayfoam.org[2] United States Environmental Protection Agency: http://www.epa.gov/dfe/pubs/projects/spf/spray_polyurethane_foam.html[3] www.sprayfoam.com
