Why This is Important
Insulation is your home’s first and most important defense in keeping the temperatures inside your home comfortable and keeping the uncomfortable temperatures outside. The better insulated your home is, the less energy it takes to keep it at the temperatures you desire, and the more stable your indoor temperatures will be. Most homes have been insulated to meet the levels required by the building code, but this still often leaves much room for improvement.
What This Will Involve
Depending on how one’s home is constructed and where in the home they are wishing to check on its insulation levels, it can either be very easy or something best left to professionals. Some insulation, like wall and foundation insulation, can be difficult for the homeowner to check unless the home is currently being renovated and is a task best left to those who have the proper equipment, while others like attic insulation can be quite simple.
For this guide we will look at ceiling insulation, as this is easy to check and change for most home owners who live in houses with attics. As we can see in figure 1, the NAIMA, or North American Insulation Manufacturers Association recommends that homes in Muncie, located in Zone 5, have R36 to R60 insulation in their ceilings, which roughly is 12″ to 20″ of fiberglass batt insulation (the kind that comes in large rolls). If your home has blown in insulation these numbers will be very similar, with blown-in cellulose insulation having a slightly higher R-value per inch of thickness. While one may think that more insulation is better and they should add as much as they can reasonably afford, adding more insulation beyond recommended levels has diminishing returns, with any insulation beyond about 20″ not adding significantly to the insulating capability of the home. This is also important in determining if your home has enough insulation or you should add more. If your home already has 15″ of insulation, adding another 5″ will not be a cost effective upgrade as the returns on it will be minimal, however a home with 10″ of insulation will see a significant improvement in adding another 10″.
After determining if your home has enough ceiling insulation, you will want to make sure that it is installed properly. For blown in insulation this just means that it is not compacted and spread evenly. For batt insulation you want to make sure that the insulation is fully covering all of the floor area of the attic. Pay special attention to the insulation between joists and make sure that there are no large gaps between the insulation and the joist. Insulation works by stopping air movement through it, so any gaps will severely reduce the actual insulating capability of your installed insulation. Also, look for areas of your insulation that have turned black or seriously darkened. This will either indicate an area where you have airflow issues, with the insulation acting as a filter for the air moving through it, or potentially moisture issues, with the discoloration being mold.
Though one can simply look at a chart to get what R-value they need for the region the live in and then buy insulation with that R-value labeled on it, it can be useful to understand what the R-value is. A short answer is that the R-value is an abstracted number that represented the rate at which thermal energy is able to be transmitted through a material. The higher the R-value, the slower thermal energy is able to move through a given material. This page from the Cellulose Insulation Manufacturers Association provides a good explanation of it for most homeowners. This Wikipedia article provides a much more technical explanation for those who wish to dig deeper into what an R-value is and how it is calculated.
This US Department of Energy guide to home insulation is a good place to start for those looking to learn more about insulation.