Traditional home insulation is made up of sheets (or blankets) of fiberglass which can be installed into walls, floors, or ceiling as needed. This type of insulation works by preventing conductive heat transfer, or the transfer of heat through solid materials. Since glass is a poor conductor (and thus a good insulator), the small strands of glass that fiberglass is composed of work by creating a maze of air pockets bounded by glass that heat cannot move through easily. This mechanism of insulation has worked well in both residential and commercial structures for decades, but it is far from the most efficient type of insulation available. Spray foam now provides a more effective and greener alternative.
What is Spray Foam Insulation?
As the name implies, spray foam insulation begins in liquid form and rapidly expands when its constituent chemicals are combined during the spraying process. Since the foam can expand to 30 times its fluid volume or more, it can fill a wide variety of spaces. This flexibility allows the use of foam in areas that would be difficult or impossible to reach with traditional fiberglass mats, and that would normally require fiberglass to be blown in. Once hardened, the foam forms a solid which is able to block both conductive and convective heat transfer.
Understanding the Terminology
If you are considering the installation of foam insulation in a new home, then the two terms you are most likely to come across are "closed cell" and "open cell." These terms refer to the structure of the foam itself. After hardening, closed-cell foam will be made up of a dense network of foam cells with solid walls. By contrast, open-cell spray foam is made up of a looser structure of cells with air gaps. Closed-cell foam is a tighter, more substantial material that is, in turn, less flexible and tends to require multiple applications. On the other hand, open-cell foam is more flexible, softer, and better able to fill irregular spaces without requiring several sprays.
The Energy Efficiency Advantages of Open Cell Foam
While spray foam has clear advantages during installation, the higher cost is a concern for many homeowners. Luckily, the cost of spray foam is largely offset by its greater energy efficiency. Both foam and fiberglass work well to prevent conductive heat transfer, but fiberglass does nothing to prevent convective heat transfer, or the flow of heat through the movement of the air itself. Since foam forms a solid barrier, it prevents warm air from easily escaping through your home's walls. Open-cell foam does not entirely prevent convective transfer, but it can efficiently prevent most of it while generally costing less than a similar closed-cell installation. By choosing to insulate your home with open-cell spray foam insulation, you will likely quickly recoup your installation costs and rapidly begin to realize savings on your energy bills.