What’s R-Value and Why Does It Matter?
Properly adding ceiling, attic and wall insulation will help improve your home’s overall comfort while saving on your heating and cooling bill. To do so, you’ll need to purchase the right kind (or combination) of insulation to maintain the optimal flow of heat into and out of your home. Simply put, an insulation’s R-value is a measurement of how well it can hold heat. The greater the R-value of foam insulation or the R-value for spray insulation, the higher the level of performance. However, you don’t have to buy insulation with the greatest R-rating available to ensure proper coverage. You only need to buy what’s recommended for the location in which you live.
Home insulation comes in various types. Some of the most common are blown-in insulation (also known as loose-fill insulation), spray-foam insulation, batt insulation, roll insulation and foam-board insulation. For more information about the different varieties available, see our Insulation Buying Guide. Not all insulation provides the same level of protection from heat loss. Each brand and type has an R-value calculated according to the density and thickness of the material. In general, products with higher insulation ratings cost more than those with a lower one.
Keep in mind that crawlspaces, attics, walls and floors in your home may contain multiple types of insulation. For example, your ceiling may be insulated with a combination of roll insulation and loose fill. To calculate the total R-value for the area, simply add the individual ratings for each type of insulation.
See How to Install Insulation for do-it-yourself instruction.
Insulation R-Value Chart
The US Department of Energy recommends insulation R-values according to local climate. Simply find where you live on the map below, then match your location’s color to the corresponding R-value chart. Note that each area of your home — attic, floor, crawlspace, etc. — will have a different recommended R-value. For example, the R-value insulation for the attic in Zone 4 would be R-38 – R-60, while the wall insulation R-value would be anywhere from R13 – R21.
To calculate how much insulation to buy for the project, check the packaging to determine the R-value rating for the thickness and calculate the thickness that’s needed. For example, if you need to achieve at least a total R-value of 40 in your attic and the type of insulation you’re purchasing is rated R-20, you’ll need enough product to stack up at least two layers in your attic.
How to Achieve Greater R-Values in Your Attic
If your attic feels drafty or your current energy costs are too high, you can easily remedy the issue by simply adding more insulation to the space. Determine the appropriate R-value recommended for attic insulation in your area then add additional layers as needed to achieve that rating. You don’t have to use all of the same type of insulation to do this. If your attic already has roll insulation installed over joists, you can add an additional layer of loose fill over the top and to fill in corners.
How to Achieve Greater R-Values in Exterior Walls
To increase the energy efficiency of your home, you can boost the R-value of walls by adding more batt insulation between wall studs or installing foam-board insulation. You can also use blown-in insulation to fill any gaps where drafts can occur. Sealing around door frames and windows with spray-foam insulation is a good idea as well.
Crawlspace Insulation, Pipe Insulation and Other Types
Along with insulating attics and walls, you can increase your home’s R-value and cut down on your monthly energy bill by addressing other places that can benefit from improved insulation.
Garage Insulation: Adding more insulation to your garage can help keep your car protected from extreme temperatures. This is also a great idea if your garage is attached to your home, as it can help maintain a consistent indoor climate.
Ceiling Insulation: Increasing insulation in your ceiling shouldn’t be overlooked as part of an overall energy-efficiency upgrade. Adding additional roof insulation may be necessary as well, depending on your home’s construction.
Pipe Insulation: Wrapping the pipes that connect to your water heater can significantly cut down on heat loss.
Crawlspace Insulation: Having a professional inspect your crawlspace and come up with an individual insulation plan, as well as a moisture-remediation strategy, if needed, will protect your home and improve energy conservation.