If you are either constructing a new house, or partaking in the task of a remodel of a current dwelling, than you have the decision to make of whether to use traditional fiberglass insulation or to use foam insulation. History tells us that the most traditional way of insulating a home is to use fiberglass. But the trend over the last couple of decades has been to insulate with foam. There are many reasons why people are gravitating towards applying spray foam, which will be discussed in more detail below. But the summary of benefits include reduced energy costs, better insulator, tighter seal, and durability.
Before I get into the benefits, I want to first give a quick summary of what foam insulation is and the various types. For a more in depth discussion, look at my spray foam insulation guide for a complete idea of what we are talking about.Foam insulation, also called spray foam or polyurethane foam, is basically what the name implies. It is a liquid that is sprayed into wall cavities, attics, roofs, basically anywhere insulation is needed. The liquid has a chemical reaction that makes it expand and turn into foam. It’s really cool stuff and fun to watch. The liquid that makes the magic foam is in two different parts. Isocyanate is one part, and remains separate from the other ingredients, and the other part consists of several different chemicals. When the two are brought together, the magic begins. One inch of liquid will turn into 5 feet of insulation in a matter of minutes.
Another thing I should point out is that there are a couple foam insulating types that one would use, dependent upon the type of work that needs to be done on the home. I will try to keep it as simple as possible, since many other websites use a lot of technical terms to describe foam insulation products.
- New Construction – Used to spray on an open wall, between studs, and sheathing, this type of foam insulation is not suitable for an older home where one would have to inject the foam into an enclosed cavity, meaning walls with drywall or sheet rock already attached. The reason is that it is too aggressive. This foam expands 100 times in no time at all.
- Slowed Down Version – With this type of foam insulation, it is injected into an existing wall through a bunch of holes that are drilled. It runs down to the body of the wall cavity and very slowly expands out and begins to grow. It works a lot slower than the new construction type of foam on purpose. Slowly rising and expanding foam will not push to hard on the existing walls and thereby lessens the chance of damage.
- The last type is what is often referred to as spray foam kits, or DIY foam kits. I won’t go into detail about this form because I have already created a guide that discusses it in more detail. Make sure to check out the do it yourself spray foam insulation guide I have put together.
This video is from an episode of “This Old House” which showcases open-cell foam insulation being applied
Table of Contents for Foam Insulation:
- Foam Insulation Insulates More
- Foam Insulation Seals
- Foam Insulation is Durable
- Foam Insulation Saves Money
Foam insulation is a much better insulator than fiberglass. Study after study has been performed, both scientific and common sense wise, and spray foam always comes up a winner. It is discussed more below, but side by side comparisons have been done that show that spray foam insulation does a better job, as is evident in home energy bill comparisons.
Fiberglass insulation batts don’t seal, but foam insulation does. It eliminates any air coming in because the foam expands and seals all areas, including outlets and hard to reach areas. One area to highlight the effectiveness of spray foam is in an attic. If you look in your attic space, you will first notice the temperature difference. But also notice the holes and cracks that might be up there. Spray foam will fill all these areas, thus keeping the temperature more constant with the rest of the house. Fiberglass would not be able to perform this task.
Another situation in which insulating with foam outperforms fiberglass is the siding of a house. I know of several remodel jobs that I have done where we had a spray foam installer come in to do the house from the outside. They pulled some of the vinyl siding off in order to create the holes necessary to inject the spray foam. When doing so, one could notice a bunch of tiny holes that were actually nail holes. Before the vinyl siding, there used to be cedar shank as a siding for the house. Then, when the vinyl siding was put on, the holes were still there. Upon further review, and this is always the case, we noticed that the current fiberglass insulation was pink, but on many areas it was brown. So basically the fiberglass worked as an air filter of sort, since air was passing in through all the nail holes. No effective or efficient, right?
Again, with foam insulation, this wouldn’t be the case. Since it fills all the cavities and any holes or cracks, no air would be able to penetrate the home. Once again, you would have a tight seal.
Foam insulation has a very long track record as being highly durable. Studies have found that spray foam ages well, even in extreme heat and moisture. The reason is that it doesn’t absorb much, if any moisture. This means that it will keep its physical properties intact for a very long time. Not only is the foam durable, but it will also add to the durability of the home by reducing air leakage and vapor diffusion,.
Foam insulation can save you a lot of money over the lifetime of owning your home. You might be surprised to find out that spray foam is not that expensive. Yes, fiberglass insulation is cheap, and you will get what you pay for. But insulating your home with foam can save you thousands of dollars in home heating and cooling costs.
The biggest differences between traditional fiberglass insulation and insulating with foam breaks down to efficiency and cost. The fiberglass insulation may be easier to install, but it doesn’t give anywhere close the efficiency of foam insulation. Additionally, the price difference upfront is very different, but the long term savings is much more apparent in foam insulation. So when it comes time to decide on an insulation type for your home, it is highly recommended to use foam insulation.