Basement Insulation and Moisture Management
There is a widely spread misconception even in today’s construction of new homes that people believe they don’t need to insulate basements. There are many reasons why basements need to be insulated.
Why Insulate a Basement?
Some people believe that because a basement is typically protected and surrounded by dirt that the dirt will insulate the basement. Think about it this way: during the winter the frost line can be anywhere from two to four feet deep. The dirt surrounding the basement is not completely up to the bottom of the siding. Up to six foot of the basement wall is below 32 degrees Fahrenheit: basically 75% of the outside of the basement wall is below 32 degrees Fahrenheit. If it’s 32 degree outside wouldn’t you wear a coat? This is the equivalent of insulating your basement walls.
Most basements are about the same equal exterior wall area as above ground walls. So if you don’t insulate the basement over half of your exterior wall is not insulated. Interestingly enough, it takes about four feet of dirt to equal the same R-Value of a two inch thick piece of foam board.
For most people it does not occur to them the moisture that is in a home is due to a “dry” basement. They are misled to believe that homes have a “dry” basement. Many new homes never get a vapor barrier. To learn more about vapor barriers, visit this blog post.
Most people believe concrete to be waterproof but this is not true. In fact it is exactly the opposite: while it may not let water in it allows capillary water transfer. According to EnviroShield, “Moisture problems are not necessarily caused by hydrostatic pressure. Concrete is hydroscopic: like a sponge it will absorb moisture from the air and if the humidity on one side of the concrete differs from the other, it will move moisture to the drier side.”
The video below will give you a good explanation as to where to install your vapor barrier and capillary breaks. It also gives you a good overview of different ways to insulate a basement:
Insulating Basement Walls
Basement walls can be insulated inside or out. But also keep in mind that you will need an air barrier. One of the biggest issues with insulating the outside of the basement comes from having to attach the insulation to the concrete wall. Another large problem occurs when attempting to protect it from damage when backfilling the basement over dig. A main concern for many home owners is that insulation on the outside of the basement is not aesthetically pleasing.
Therefore, your best option is to insulate from the inside. There are a variety of options to choose from: you can attach a foam board to the wall or hang vinyl-backed fiberglass rolls from the rim joist area down. The fiberglass method has become the favorite for the “Economy Production Home Builders” you see now. The fiberglass rolls are often called “diapers” in the construction world because they look like diapers and have a tendency to absorb water in the same manner.
The last way to insulate the basement is to stud it up like an exterior wall would be and install batt insulation or spray foam insulation. This is the best way to insulate the basement wall. If you install fiberglass insulation in the basement you will need to be sure to control moisture in the concrete. If moisture is not controlled the perfect environment for mold growth is made.
The simplest and most recommended way to insulate a basement wall is with closed cell spray foam insulation. To learn more about the specifics of closed cell spray foam insulation, visit this link.
Closed cell spray foam insulation is an air barrier, a vapor barrier, a drain plain, and insulation all in one simple step. It solves all of these problems in one. Wood foundation basements can also really benefit from close cell spray foam insulation.
Many home basements are not insulated. When finishing a basement this is a great time to insulate it. Give Iowa Spray Foam a call and let us help you insulate your basement with closed cell spray foam insulation.