Many people wonder if spray foam insulation is actually “spraying foam.” The answer to this question is no. What is Spray Foam Insulation? It is an inflatable (plastic) product filled with either a liquid or gelled polyurethane. When sprayed on a structure, it fills the space between the ceiling and the surface beneath it.
The spray foam insulation that is most often used is a foam product that expands in response to air movement. Spray foam is also known as ‘plastic foam,’ ‘waffle,’ or ‘pellets.’ It is manufactured from two chemicals, isocyanate, and chlorobenzene acid, which react when combined and expand 30 times their volume when it is sprayed over exposed surfaces. That’s why it is sometimes referred to as “air cushions” because they can provide a certain amount of comfort and cushioning to occupants of an area that might otherwise be cold or drafty.
There are two types of spray foam insulation available – open and closed-cell. Open-cell foams have smaller cavities than closed cells, and these cavities are sealed off from one another. This means that the open-cell type of spray foam insulation has less insulation than the closed-cell type. However, the extra insulation provided by the closed-cell variety is much greater.
The closed cell form of spray foam insulation can be sprayed onto insulated concrete slabs (also called skirting boards), which are installed right above the finished floor slab on the attic floor. A skirting board is simply a piece of lumber, quite long and wide enough to accommodate most sprayed-in insulation packages. In fact, a skirting board can be installed on any floor surface, but must be parallel to the wall in order to accomplish an even application. Typically, a skirting board is put into place as the first layer of insulation on the exterior walls, with an open cell construction of spray foam insulation above it.
The second type of spray foam insulation product, closed cell foam, is used in building enclosures and sprayed directly onto exterior walls, floors, ceilings and other interior surfaces. With this product, there is no need for a skirting board, so it can be installed almost anywhere. In fact, the closed cell foam that is sprayed onto concrete slabs serves two purposes. One, the spray foam insulation forms a protective barrier against moisture escape from the structure of the building enclosure itself. Two, the spray foam insulation also provides a barrier against draft from the exterior of the building enclosure.
The spray foam insulation is sprayed into a space big enough to allow for proper coverage, which is about five feet by three feet. Once the spraying process is complete, an air seal is created to keep the moisture in while preventing any form of water or vapor from escaping. Since there is no skirting or baffle work involved, there is little chance for air to seep out of the structure of the roof and condensation to occur. Unfortunately, this method does not prevent cold air from penetrating into the structure of the roof or attic, so it is necessary to maintain adequate heating and air conditioning ductwork throughout the structure of the home in order to prevent ice dams and thick ice sheets from forming on flat surfaces.
Another way to reduce noise is by using insulation on the roof. The spray foam insulation can also be placed between the ceiling joists, where insulation is commonly applied, and the walls in between these ceiling joists, creating a barrier between them. There are other ways to create a barrier, as well, such as installing soundproofing on the floors and between the floors and ceiling. Other applications of the spray foam insulation will include attics and basements. Installing insulation to create a soundproof barrier between the attic and exterior walls of the home is especially useful when doing extensive remodeling. Also, installing insulation to reduce noise is important if you’re planning to add a room above your home to increase living space, thus creating more sleeping space.
Although spray foam insulation may not be as effective in terms of insulating a home’s interior as it is its exterior, it still provides excellent soundproofing and insulating properties. Many spray foam products are designed to achieve very high R-values. They are particularly effective in reducing noise by about 40% compared to other forms of insulation. Even though spray foam has low thermal conductivity, some manufacturers combine it with other materials such as polyurethane foam or polyisocyanurate to create greater insulating properties. These combinations are often called isocyanates.