Although many upgrades can help turn a house into a more comfortable home, perhaps none is more important than keeping it cool in the summer and warm in the winter. Insulating and air sealing your home not only makes it more comfortable, but also lowers energy bills and prevents unwanted outdoor air pollutants from entering the home.
One of the most important but least discussed insulation areas of a home is the rim joists in the basement. With the different options available for insulation, should you spray foam rim joists? In short, insulating rim joists can make a measurable difference in a home’s comfort and energy use, and the qualities of spray foam insulation make it the right insulation material for the job.
What Are Rim Joists?
Rim joists are part of a home’s floor framing. These joists are connected to the home’s foundation and run perpendicular to the floor joists. Rim joists and end joists form the sections of the floor frame that are exposed to the outdoors, making them a natural target for air leakage and, therefore, a necessary location for insulation.
Why Do Rim Joists Need to Be Insulated?
Because of their exposure to the outdoors, rim joists and end joists are the most likely areas of a basement for heat to escape during the winter and enter during the summer. Air sealing and insulating rim joists and end joists offers an additional layer of protection to keep outdoor temperatures and air outside and maintain a comfortable temperature inside.
Spray foaming rim joists offers excellent air sealing and thermal resistance. Rim Joists need to be insulated because it will reduce heat loss & lower energy bills, which will lower your carbon footprint, improve indoor comfort, reduce the amount of humidity or moisture in your basement, and it’s cost effective with the long term savings.
How Rim Joists Affect Home Comfort
A home’s basement is a major contributing factor to the indoor temperature and comfort of every room of the house. During the winter, a cold basement can mean cold floors, which creates a chilly and uncomfortable living space. Because the rim joists are exposed directly to the outdoor environment by virtue of their position, they can be a major contributor to basement drafts and cold floors when left uninsulated. By the same token, properly insulated rim joists will help keep indoor temperatures consistent throughout the seasons and reduce unwanted rodents and pests.
The Benefits of Using Spray Foam for Basement Rim Joists
Spray foam is a good choice for insulating basement rim joists. Basements can be damp and sources of indoor moisture, which can damage and weaken the performance of many insulation materials. Closed cell spray foam rim joist insulation has a few benefits that other insulation types like fiberglass and cellulose lack, such as:
- Acts as both insulation and an air sealant
- Does not retain water and acts as a water and vapor barrier to prevent mold and mildew
- Does not attract insects or other pests, which can be common issues for rim joists that sit at ground level
- Reduces carbon footprint and will contribute to long term savings
- Keeping rim joists dry and at a stable temperature can extend the life of these and adjacent materials
These unique qualities make spray foam a long-lasting and effective choice for insulating the rim joists in your basement.
Other Options for Rim Joist Insulation
Fiberglass or cellulose insulation may be used in place of spray foam to insulate rim joists. However, in addition to benefits outlined above, spray foam is simply the most effective way to seal gaps around rim joists. Once spray foam is installed it hardens and does not leave cracks or gaps where air can escape. Furthermore, hardened open cell spray foam insulation stays in place for years.
How Our Team Insulates Rim Joists
The insulation experts at Wisconsin Home Improvement Co. LLC know how to insulate rim joists efficiently and effectively. The team starts with creating an airtight seal using expanding spray foam insulation for a secure vapor barrier. From there, we either use rigid insulation or additional spray foam to fill the remainder of the rim joist cavity.
Schedule a Home Performance Audit Today to Get Started
The best way to tell if your home could benefit from rim joist insulation is with a home performance energy audit. Using infrared thermal imaging and a blower door test, the Wisconsin Home Improvement team can pinpoint the air leaks throughout your entire home. An energy audit will also ensure all your combustion appliances are running safely and will alert you to any other areas where home upgrades would benefit you.
