Insulation's ability to slow the transfer of heat or cold is called thermal performance and is measured in R-values. Thermal performance means greater year-round comfort and increased control over energy usage.
The U.S. Department of Energy has established minimum recommended insulation R-values for six distinct parts of the country, or insulation zones. Determine your insulation zone by locating your city or town on the map. If you live on the border between two zones, choose the higher rather than the lower values.
Insulation
Zone |
Gas |
Heat
Pump |
Fuel
Oil |
Electric
Furnace |
Attic |
Wall |
Floor |
Crawl
Space |
Basement |
| 1 |
X |
X |
X |
|
R-49 |
R-18 |
R-25 |
R-19 |
R-11 |
|
|
|
X |
R-49 |
R-28 |
R-25 |
R-19 |
R-19 |
| 2 |
X |
X |
X |
|
R-49 |
R-18 |
R-25 |
R-19 |
R-11 |
|
|
|
X |
R-49 |
R-22 |
R-25 |
R-19 |
R-19 |
| 3 |
X |
X |
X |
X |
R-49 |
R-18 |
R-25 |
R-19 |
R-11 |
| 4 |
X |
X |
X |
|
R-38 |
R-13 |
R-13 |
R-19 |
R-11 |
|
|
|
X |
R-49 |
R-18 |
R-25 |
R-19 |
R-11 |
| 5 |
X |
|
|
|
R-38 |
R-13 |
R-11 |
R-13 |
R-11 |
|
X |
X |
|
R-38 |
R-13 |
R-13 |
R-19 |
R-11 |
|
|
|
X |
R-49 |
R-18 |
R-25 |
R-19 |
R-11 |
| 6 |
X |
|
|
|
R-22 |
R-11 |
R-11 |
R-11 |
R-11 |
|
X |
X |
|
R-38 |
R-13 |
R-11 |
R-13 |
R-11 |
|
|
|
X |
R-49 |
R-18 |
R-25 |
R-19 |
R-11 |
(A)
R-18, R-22 and R-28 exterior wall systems can be achieved by either cavity insulation or cavity insulation with insulating sheathing.
For 2" x 4" walls, use either R-15 or R-13 fiberglass with insulating sheathing.
For 2" x 6" walls, use either R-21 or R-19 fiberglass insulation.
(B)
Insulate crawlspace walls only if the crawlspace is dry all year, the floor above is not insulated, and all ventilation to the crawlspace is blocked. A vapor retarder (e.g., 4 or 6-mil polyethylene film) should be installed on the ground to reduce moisture migration into the crawlspace.
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