R Value Insulation Guide

Find out everything you’ve ever wanted to know about the R value of insulation. Included is our R value guide, detailing the suggested amount of insulation dependent upon zone, as provided by the U.S. Department of Energy. Also included is the hugely helpful insulation zip code calculator that spells out the suggested amount of R value necessary for the different portions of a structure, like foundation, interior and exterior walls, attic and more.

Insulation R Value Calculator

Find out the suggested amount of insulation R value necessary for a structure!

Search by zip code. Ex: 44278


Recommended Insulation R Value by Zone

This map illustrates the eight U.S. zones that determine how much insulation is needed based on recommendations from the U.S. Department of Energy (DOE) and the International Energy Conservation Code (IECC).

Insulation R Value by Zone Chart

Zone Attic Floor Wall
Uninsulated Attic Existing 3-4 Inches of Insulation Uninsulated Floor Uninsulated Wood-Frame Wall Insulated Wood-Frame Wall
 1  R30 to R49  R25 to R30  R13  *  N/A
 2  R30 to R60  R25 to R38  R13 to R19
3  R19 to R25 * and add R5 insulative wall sheathing beneath the new siding
4  R38 to R60  R38  R25 to R 30 Add R5 insulative wall sheathing before installing the new siding
5 R49 to R60  R38 to R49 * and add R5 to R6 insulative wall sheathing beneath the new siding
 * Whenever exterior siding is removed from an uninsulated wood-frame wall, drill holes in the sheathing and blow insulation into the empty wall cavity before installing the new siding.

What is R Value?

“R” means resistance to heat flow. The higher the R-value, the greater the insulating power. Compare insulation R-values before you buy. There are other factors to consider. The amount of insulation you need depends mainly on the climate you live in. Also, your fuel savings from insulation will depend on the climate, the type and size of house, the amount of insulation already in your house, and your fuel-use patterns and family size. If you buy too much insulation, it will cost you more than what you’ll save on fuel. To get the marked R-value, it is essential that this insulation be installed properly.

Proper Installation of INSULPINK® 7.5 R Value Rigid Insulation Board

R Value by Material

Material Type R Value Cost / sq. ft. Cost / sq. ft. per R value
Fiberglass batt 13-30 $0.20-$1.00 $0.02-0.03
Loose fill such as fiberglass, cellulose
& mineral wool (8-23 inches thick)
30-50 $0.45-$2.25 $0.03
Open cell polyurethane spray foam
(3.5 inches thick)
12.6 $1.70-$2.50 $0.17
Closed cell polystyrene spray foam
(1 inch thick)
6.5 $1.30-2.00 $0.25
Expanded polystyrene foam board
(1 inch thick)
3.8-4.4 $0.20-0.35 $0.07
Extruded polystyrene foam board
(1 inch thick)
5 $0.40-0.55 $0.10
Polyisocyanurate foam board
(1 inch thick)
6.5 $0.60-0.70 $0.10