FAQ Informational

Insulation R-Value Chart

by |Published -Updated

SVB Conglomerate, Inc. has taken the liberty of providing you with the information that displays the various R-Factors, and other information that is helpful in choosing the insulation for your home. Particularly as we are located in Climate Zone 2, central Texas, Austin Metro region. In this informative article you will learn:

    • The importance of choosing quality insulation for your home’s insulation system
    • What the system of “R-Value” means and how to calculate its effects upon your home
    • The various R-Values based upon your location and heat type (helpful charts included)

A home’s insulation is perhaps one of the least thought about aspects during the building phase. It is never seen and rarely does a homeowner give it a second thought. Although, if one is pursuing an energy efficient home, some consideration should be given to this often overlooked aspect of the building envelope. As it is commonly stated, “Not all things are created equal.” There is the number of various materials from which insulation can be comprised of; such as fiberglass and cellulose as well as a number of different varieties such as batting and polyurethane spray foam.

The one common denominator amongst the various forms of insulation is the R-Value. In short, the R-Value is the measurement of thermal resistance and it measures the ability of heat to transfer from one side of an object to another. As a benchmark, one inch of solid wood has an R-Value of 1. For comparative purposes, an inch of industry standard Fiberglass Batting has an R-Value of 3.1 – 3.4 whereas an inch of polyurethane closed cell spray foam has an R-Value of 6.0 – 6.5.

Even with having the information regarding the various insulation’s R-Value, it is also important to remember that one needs to calculate the R-Value of a home’s entire insulation system. As an example, a home’s wall with 3-1/2″ fiberglass batting (R-Value of 10.8 – 11.9) may have an overall R-Value of nearly 14 because of the following: siding, sheathing, and drywall.

Lastly, there are no set standards for insulation in a given geographic area. There are several factors that one must determine to calculate the type of insulation to use, and just how much or how little is to be utilized in the construction of your home. Some of the factors included are your geographic location as well as the style of the heating system utilized. The chart below outlines the R-Value recommendation for different areas in your home, as well as the various zones outlined by energystar.gov. The chart also provides common insulation types as well as their accompanying R-Value.

IECC climate zone map

Insulation R-Values by location, heat type, and area1

LocationHeat TypeAtticWallFloorCrawl Space Wall2Basement Wall
Zone 1Natural Gas
38-4913131311
Oil Furnace38-4913131311
Electric Furnace38-4913131311
Electric Baseboard38-4913131311
Heat Pump38-4913131311
LPG Furnace38-4913131311
Zone 2Natural Gas
381313-191311
Oil Furnace381313-1913-2511
Electric Furnace38-491319-252511
Electric Baseboard38-491313-2513-2511
Heat Pump381313-191311
LPG Furnace38-491319-302511
Zone 3Natural Gas
30-381313-1913-2511
Oil Furnace381313-191311
Electric Furnace381313-1913-2511
Electric Baseboard381313-191311
Heat Pump30-3813131311
LPG Furnace38-491313-3013-2511
Zone 4Natural Gas
38-491325-302511
Oil Furnace4913302511
Electric Furnace38-491325-302525
Electric Baseboard4913302511
Heat Pump38-491313-2513-2511
LPG Furnace4913302511-25
Zone 5Natural Gas
3813252511
Oil Furnace4913302511-15
Electric Furnace4913302525
Electric Baseboard4913302511
Heat Pump3813302511
LPG Furnace4913302525
Zone 5Natural Gas
4913303025
Oil Furnace4913303025
Electric Furnace4913302525
Electric Baseboard4913302525
Heat Pump4913302525
LPG Furnace4913302525
1 Ranges resulted from the selection of two different zip codes within the same zone (i.e. Dover, DE and Chattanooga, TN for zone 4)
2 Crawl space walls that are vented or have moist problems should not be insulated.

R-Values of Materials & Depths

MaterialR-value/in3 1/2″5 1/4″10"12"15"
Fiberglass (batt)3.1 – 3.410.8 – 11.916.3 – 17.831.0 – 34.037.2 – 40.846.5 – 51.0
Fiberglass blown (attic)2.2 – 4.37.7 – 15.0 11.5 – 22.622.0 – 43.026.4 – 51.633.0 – 64.5
Fiberglass blown (wall)3.7 – 4.3 12.9 – 15.019.4 – 22.637.0 – 43.044.4 – 51.655.5 – 64.5
Mineral Wool (batt)3.1 – 3.410.8 – 11.916.3 – 17.831.0 – 34.037.2 – 40.846.5 – 51.0
Mineral Wool blown (attic)3.1 – 4.010.8 – 14.016.3 – 21.031.0 – 40.037.2 – 48.046.5 – 60.0
Mineral Wool blown (wall)3.1 – 4.010.8 – 14.016.3 – 21.031.0 – 40.037.2 – 48.046.5 – 60.0
Cellulose blown (attic)3.2 – 3.711.2 – 12.916.8 – 15.032.0 – 37.038.4 – 44.448.0 – 55.5
Cellulose blown (wall)3.8 – 3.913.3 – 13.619.9 – 20.838.0 – 39.045.6 – 46.857.0 – 58.
Polystyrene Board3.8 – 5.013.3 – 17.519.9 – 26.238.0 – 50.045.6 – 60.057.0 – 75.0
Polyisocyanurate (foil-faced)5.6 – 8.018.2 – 28.029.4 – 42.056.0 – 80.067.2 – 96.084.0 – 120.0
Open Cell Spray Foam3.5 – 3.612.2 – 12.618.4 – 18.935.0 – 36.042.0 – 43.252.5 – 54.0
Closed Cell Spray Foam6.0 – 6.521.0 – 22.731.5 – 34.160.0 – 65.072.0 – 78.090.0 – 97.5
This table provides the various materials used within the construction industry to provide insulation to your building project. The R-Values are provided under each row, shown at the depth of the provided insulation.

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