Masonry Magazine November 2002 Page. 29
The complex chemical
The complex chemical nature of the three-component foam creates some interesting physical characteristics.
The growing popularity of generic foamed-in-place insulation is benefiting mason contractors across America because they are finding the price, effectiveness and convenience of using this product can cut labor costs and increase profits while providing an energy efficient wall.
Some call it an amino-plast resin, while others prefer oligomeric polymethylene carbonate. The most descriptive word for all these products, however, is urea-formaldehyde foam insulation.
The product is being used in everything from schools, high-rises, retail boxes, and football stadiums to basement foundation walls and hollow-core concrete panels. Yet, architects and contractors alike know very little about it. Questions abound regarding its physical attributes, correct application techniques, chemical composition and potential hazards, and quality control procedures.
The most common point of confusion is how it compares to polyurethane foam insulation, a generically different product with completely different physical properties. One thing is assured, twenty years after the rebirth of urea-formaldehyde foam insulation, it has proven its effectiveness and popularity within the block industry.
History
ORIGINALLY DEVELOPED by the Germans in the 1930s and widely used in manufacturing of plywood, carpets, dyes, and many other products, urea-formaldehyde foam was first brought to the United States in 1959. In 1968, the first foam insulation product was manufactured in New York. After a slow start the product took off during the Arab oil embargo of the early '70s when insulation terms like R-factor and building thermal efficiency became hot topics with homeowners and builders alike as the price of heating and cooling houses dramatically increased.
The vast majority of contractors pumping foam in the '70s were home improvement contractors. The foam was the ideal product for injecting into uninsulated walls, significantly increasing the R-value (resistance to heat and cooling loss) of the walls of most homes. At its peak in the early 1980s, it is estimated that over 1200 contractors were pumping foam in the United States and Canada. By 1982, though, the growth of this booming industry came to a screeching halt.
In 1982, the Consumer Product Safety Commission (CPSC) forced the product off the market, alleging that it was a carcinogen. With the immense amount of publicity and media attention that followed, the product was soon limited to commercial applications.
An average two man crew should be able to drill, fill and patch about 4000 square feet per day.
In April 1983, the US Court of Appeals for the Fifth Circuit overturned the ban, stating that the CPSC's data and methodology was "not good science." The court criticized the claim that foams presented a cancer risk of between 0 and 51 in a million. On close examination it was found that the U.S. Chemical Industry Institute of Toxicology's report that found formaldehyde caused nasal cancer in rats (not mice, in the same experiment), was based on an exposure to formaldehyde at levels 300 to 600 times greater than the normal exposure in an average house. While the ban was overturned, the damage was done to a relatively young and vulnerable growth industry.
Physical attributes
OVER THE PAST 20 YEARS, the product has re-defined itself as the ideal product for core filling concrete masonry units. The foam is injected through small holes in the mortar joints or top-filled into the cells where it flows under about 55 - 75 psi of air pressure. When fresh, it looks like a thick shaving cream, drying or "curing" to a consistency similar to a stale angel food cake.
As it is injected, it seeks out and fills all available air spaces, providing an excellent insulation value for the integral wall unit. Unlike loose fill materials, it will not settle or flow out weep holes.
The complex chemical nature of the three-component foam creates some interesting physical characteristics. Produced at the job-site by the installing contractor, the foam consists of a urea-formaldehyde liquid resin, a liquid emulsifier or foaming agent with a catalyst, and compressed air. When these three agents merge at the end of the application gun, the initially acid mixture becomes neutral. To effectuate a complete reaction, a minimum length of four to six feet of application hose is required. The foam will flow out the application hose and move throughout the wall until it reaches its setting point. At this time it solidifies and prevents further flow. Once the foam sets up, it cannot be broken down by water.
While often referred to as a "40 percent open, 60 percent closed cell product, the cellular structure is more accurately described as an interspersed capillary structure. This makes it ideally suited for sound insulation and the tiny air cells make it an excellent insulator with R-values ranging from 4.7 to 5.2 per inch.
The density of the product varies greatly from its initial installed wet stage of approximately 2.8 pounds per cubic foot