His name is David Holmes from Cozy Domes and Cozy Spray Foam Enterprises from Northern Minnesota. The website is Cozy Dome Homes
There are many reasons why one might write an informative article on Sprayed Urethane Foam insulation. Our generation is not lacking in those who collect data and market in E-books, industry magazines and the like. I’m getting too old to want to impress anyone with information that I’ve collected. I’ve sprayed Polyurethane foam insulation for over 14 years (I’m now 55) and have diligently pursued a higher order of understanding. I must say that the greatest levels of understanding are more profound through simplicity. I wish to explain in simplicity something of solid foam insulation, fiber insulation and the things that I’ve witnessed and come to understand.
In a nut shell, Sprayed Polyurethane Foam insulation is a 2 component plastic foam engineered for different applications in different densities. The heavier density, the stronger the foam (increased compressive strength). The lightest density 2 component foams are open celled and start at about ½ pound density per cubic foot. These foams have an r-value in the range of 3.5 to 3.6 or so per inch of sprayed thickness. ½ pound foams use carbon dioxide as the blowing agent to form the cells generated from water in the mix design. Closed cell 2 component foams start at a density of about 1.7 pounds per cubic foot (which is a summer grade density only, not sprayed in other seasons generally).The blowing agent in higher density foams boils at about 49 degrees Fahrenheit, so care must be taken in handling the B component which holds it in suspension. Bumpy truck rides on hot summer days make for an interesting scenario. The most common sprayed house insulation foams are 1.8 to 1.9 pound densities. Roof density foams have a density of up to 3 pounds per cubic foot and a compressive strength of over 50 psi. Closed cell foams, which are my preference for many reasons, have an r-value in the range of 6.5 per inch. The manufacturers work at producing insulation foams with a stable cell structure that will withstand temperature changes to the extremes and maintain consistent performance. Suffice it to say that this is not as simple as it sounds but my hat goes off to the manufacturer’s chemists who most of the time have done a great job.
In the last few decades, beginning with huge increases in energy costs in the 70′s, there has been an endless drive toward energy efficiency in this country. In a general sense, this has been a good thing, but much confusion has arisen as to how to accomplish this goal.
A great emphasis was put on vapor barriers some years ago. Some thought it would be better to have one on the inside and one on the outside of the fiber insulated wall. This was a disaster. There has been more mold issues in the last few decades than anyone wants to admit. Understanding has greatly improved and for some time plastic vapor barriers have been installed on the interior side alone of the insulation.. Let me explain the issues strictly from my personal experience.
The problems associated with insulating house walls have never been vapor drive per say. The issues causing inefficiency, and mold in walls are simply summed up in air migrating through the walls with condensation of the water vapor in the cool outer parts of the wall. In summer months the mechanism reversers with condensation taking place on the interior wall when hot, humid air condenses moisture on wall sheeting. Some years ago government studies concluded that up to 40% of our heating bills in our homes were due to air infiltration.
If you want top efficiency, you must have a tightly sealed wall. If you want a tightly sealed building without the occurrence of mold, you must have a complete separation of outside and inside climates with no wall cavities serving as mixing chambers where condensation can take place. There are a few different ways to accomplish this. My experiences involve using closed cell urethane foam. This provides an absolute sealing of walls with no condensation issues whatsoever. Because the sprayed in place foam expands about 33 times in volume and sticks well to most substrates, a complete seal of the wall cavity takes place. Because air cannot penetrate through the foam and the surface of the foam remains at the interior air temperature, condensation cannot take place. Many decades ago people used sawdust and other cheap fibers in coolers walls and freezers. Today all of our high efficiency refrigerators, freezers and hot water heaters utilize urethane foam insulation to achieve the high efficiency levels with an absolute separation of the two climates (inside and outside the unit being heated or cooled). Old time freezers or coolers would eventually have their sawdust become soaked with water by the same mechanism that moistens the fiber insulations in your walls.
So, is this always the case with fiber insulations? No, but one must remember that you cannot tighten a wall up with fibers insulations so tight that it cannot breathe and release the moisture that can accumulate at times.
Many of us prefer building materials that are more natural and give us less exposure to synthetics etc. I like this idea also, but I have learned that the most damaging exposure that we can have in our homes is mold and mold that is caused by the process I have described in this article. I have personally had to endure with my wife and children, exposure to mold that left us sensitized and suffering. Avoid mold by all means and provide fresh air exchange and reduced humidity in your structures. Building code requires fresh air exchange units in new homes these days which is a good thing, reducing carbon dioxide levels and humidity.
When we come to understand how these mechanisms function in heating, air conditioning and insulating, we can understand that r-values alone cannot measure thermal efficiency. Because of its ability to achieve separation of interior and exterior climates, Polyurethane foam has shown in anecdotal evidence to far more effective than equal r-value in fiber insulation. I would say that this principle holds true for Styrofoam boardstock (when sealed against air infiltration) and Styrofoam concrete wall forms as well.
We have lived in northwest Minnesota for the last 8 years and are camped out in a metal Quonset building while our home is under construction (foam insulated concrete domes that our family is building). We only have 2 inches of foam on the inside of this building which is an R-13. We stay warm and comfortable, but what do I know, we’ve only seen 52 degrees below zero. Visitors are amazed at how easy it is to maintain heat in this building. Because spray in place urethane foam does not allow air infiltration and remains consistent with varying humidity and wind conditions, the performance is more consistent and predictable.
In the southwestern United States some building is being done using light weight pumice aggregate. Thick walls (12 to 14 inches thick) are poured without fine aggregate and Portland cement used at only 3 bags per yard. This creates a light density wall honeycombed with air pockets that produce a wall with an r-value of 1 ½ per inch and enough compressive strength to support up to 2 stories. The interior and exterior of the wall is finished with a cement stucco trowled on. Because this type of wall can absorb and release moisture, this would be considered to be a breathable wall from both sides with no air migration to cause heat loss or moisture condensation.
In many parts of the world, solid breathable walls are used to achieve efficiency with air quality preserved.
When you understand the principles, you can far more effectively work with the insulation materials that you have chosen to achieve a safe, healthy environment.
Fiber insulations will work for some applications.