What R-Value Insulation Do I Need?

What R-Value Insulation Do I Need?

October 14, 2021

The R-value of insulation measures its ability to resist heat flow. Higher R-value for insulation means a better ability to insulate the home and resist heat transfer into or out of the home.

The entire purpose of insulating the home is to make sure you can keep your warm air inside during the winter months and outside during the summer. R-value measurements give you a number to better quantify that ability when comparing potential insulation types.

Depending on where in the United States you live, your recommended R-values will vary. In most cases, the Department of Energy will recommend exterior walls feature R-13 to R-23, with R-30, R-38 and R-49 being the most popular recommendations for ceilings and attic spaces. But again, recommendations vary based on location.

Here’s a quick look at the DOE’s recommendations based on environmental zone.

  • Zone 7: Zone 7 includes the very northernmost parts of Maine and the Midwest, as well as some mountainous regions of Colorado and Wyoming. In this zone, the DOE recommends R-49 to R-60 for the attic, R-13 to R-15 for 2×4 walls, R-19 to R-21 for 2×6 walls and R-25 to R-30 for floors and crawl spaces.
  • Zone 6: Zone 6 includes much of the upper Midwest, Wyoming, Montana and much of the northeast. Recommendations for this zone are the same as for Zone 7.
  • Zone 5: Zone 5 includes much of the Midwest and Great Plains, much of the mountainous region of the west, and a band across the northeast. DOE recommendations here are the same as for Zone 7 and Zone 6 except for attics, where they recommend the use of R-38 to R-60.
  • Zone 4: Zone 4 features the coast in the Pacific Northwest, much of the middle of the United States and much of Pennsylvania, Massachusetts and neighboring states. The insulation needs here are the same as in Zone 5.
  • Zone 3: Zone 3 covers much of the California coast and a large stretch of the southern United States in Arizona, New Mexico, Texas, Arkansas, Oklahoma, Louisiana, Mississippi, Alabama, Georgia and South Carolina. Here the recommendations are to use R-30 to R-60 for attics, R-13 to R-15 for 2×4 walls, R-19 to R-21 for 2×6 walls, R-25 for floors and R-19 to R-25 for crawl spaces.
  • Zone 2: Zone 2 can be found in some of the hottest areas of the country, including the southern sections of Arizona, California, Texas, Louisiana, Mississippi, Alabama, Georgia and most of Florida. The recommendations here are to use R-30 to R-49 for attics, R-13 to R-15 for 2×4 walls, R-19 to R-21 for 2×6 walls, R-13 for floors and R-13 to R-19 for crawl spaces.
  • Zone 1: Zone one is only found in the very southernmost tip of Florida in the contiguous United States. Its recommendations are the same as Zone 2, except for the use of R-13 in crawl spaces.

What R-value insulation for walls, floors and crawl spaces is appropriate for the area where you live? Contact us today at High Plains Engineering & Design, LLC for more tips.

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