What is the highest R value for wall insulation?
Mia Walsh
Published May 27, 2026
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Hereof, what is a good R value for exterior walls?
Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces. See the Department of Energy's (DOE) ranges for recommended levels of insulation below.
Furthermore, which insulation is best for walls? The best insulation options for an attic are open cell spray foam, fiberglass, and cellulose.
- Cellulose is the oldest insulation material used for not only the attic, but other areas of the home as well.
- Fiberglass is another traditional insulation material that consists of extremely fine glass fibers.
In this regard, what is the highest R value for insulation on 2x4 wall?
Fiberglass vats are the standard insulator for 2-inch by 4-inch wall framing, and are rated R-11 through R-15. In order to achieve the higher insulation R-value of R-21 a different type of insulation will be required.
What type of insulation has the lowest R value per inch?
Comparative Insulation R-Values
| Insulation Type: | R-Value per Inch: |
|---|---|
| Fiberglass (loose) | 2.2 – 2.9 |
| Fiberglass (batts) | 2.9 – 3.8 |
| Cellulose (loose) | 3.1 – 3.8 |
| Stone Wool (loose) | 2.2 – 3.3 |
What is a good R value for wall insulation?
Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces. See the Department of Energy's (DOE) ranges for recommended levels of insulation below.What is the thinnest insulation with the highest R value?
OPTIM-R is Kingspan's thinnest insulation. It comprises of a rigid vacuum insulation panel with a micro porous core which is evacuated, encased and sealed in a thin, gas-tight envelope which gives an outstanding thermal conductivity of 0.007 W/m.K.What is a good insulation R value?
R-Values| Add Insulation to Attic | ||
|---|---|---|
| Zone | Uninsulated Attic | Existing 3-4 Inches of Insulation |
| 1 | R30 to R49 | R25 to R30 |
| 2 | R30 to R60 | R25 to R38 |
| 3 | R30 to R60 | R25 to R38 |