R-Value Calculator
Find the recommended insulation R-values for your location based on IECC climate zones and Energy Star guidelines.
Find Your R-Value Requirements
Enter your ZIP code to find the IECC-recommended insulation R-values for your climate zone.
Zone 1 = Hottest (Florida, Hawaii) | Zone 8 = Coldest (Alaska)
Understanding R-Value Requirements
What is R-Value?
R-value measures insulation's resistance to heat flow. The higher the R-value, the better the insulation performs. Different areas of your home need different R-values based on your climate zone and how heat moves through the building envelope.
About IECC Climate Zones
The International Energy Conservation Code (IECC) divides the United States into 8 climate zones, from Zone 1 (very hot/humid) to Zone 8 (subarctic). Each zone has specific minimum R-value requirements for different parts of a building.
Important Note
The R-values shown are 2021 IECC minimums. Your local building codes may require higher values. Always check with your local building department before starting an insulation project.
Code Minimum vs. Recommended
Code minimums are the legal requirements for new construction. However, Energy Star and building science experts often recommend exceeding these minimums for better comfort, lower energy bills, and future-proofing your home. The calculator shows both to help you make an informed decision.
Understanding "ci" Notation
When you see "ci" (continuous insulation) in the requirements, it means insulation installed on the exterior of the framing without thermal bridging through studs. For example, "R-13+5ci" means R-13 in the wall cavity plus R-5 continuous insulation on the outside.
Related Resources
R-Value Chart
Complete reference of R-values for all insulation types.
Climate Zone Map
Interactive map of IECC climate zones.
Cost Calculator
Estimate material and installation costs.
What is R-Value?
Learn how R-value works and why it matters.
Thickness Calculator
Find out how thick your insulation needs to be.
Insulation Quiz
Get personalized insulation recommendations.
Frequently Asked Questions
Why does my attic need higher R-values than my walls?
Heat rises, so the attic is where most heat escapes in winter. Additionally, there's typically more space in an attic to add insulation, and it's more cost-effective to add thickness there than in walls where space is limited.
What if my ZIP code shows a different zone than I expected?
Climate zones can vary within counties, especially near zone boundaries or in mountainous areas. If you're unsure, check with your local building department or use the manual zone selection based on the official IECC climate zone map.
Do these R-values apply to existing homes?
The IECC requirements technically apply to new construction. However, when retrofitting an existing home, these values serve as excellent targets. Your local utility may have specific rebate programs that reference these or similar R-value targets.
What does "NR" (Not Required) mean?
NR means the code doesn't require insulation in that location for your climate zone. However, you may still benefit from insulation there for comfort or energy savings. For example, Zone 1 doesn't require basement wall insulation by code, but adding some can still improve comfort.