When installing brown cellulose insulation in an attic, how many inches of insulation are needed to have a R38 if the R factor is 3.1 per inch?

When installing brown cellulose insulation in an attic, how many inches of insulation are needed to have a R38 if the R factor is 3.1 per inch?

• A. 8
• B. 12
• C. 14
• D. 16

Answer: (B)

To achieve an R-value of R38 using cellulose insulation with an R-factor of 3.1 per inch, you need to determine how many inches of insulation are required. The R-value represents the insulation's effectiveness, and the higher the R-value, the better the insulation performs in resisting heat flow. To calculate the total thickness needed, you can divide the desired R-value by the R-value per inch. In this case, you take the target R-value of 38 and divide it by the R-factor of 3.1: R-value needed / R-factor per inch = Inches of insulation needed 38 / 3.1 ≈ 12.26 Since insulation is typically measured in whole inches, you would round this number up to the nearest whole inch, which gives you 12 inches. This calculation shows that 12 inches of brown cellulose insulation is necessary to achieve the desired R38 rating, making it the correct choice. Other options present numbers outside of the calculated inches required, which would either result in insufficient insulation (lower R-value) or excessive insulation that goes beyond what is necessary to reach R38.

To achieve an R-value of R38 using cellulose insulation with an R-factor of 3.1 per inch, you need to determine how many inches of insulation are required. The R-value represents the insulation's effectiveness, and the higher the R-value, the better the insulation performs in resisting heat flow.

To calculate the total thickness needed, you can divide the desired R-value by the R-value per inch. In this case, you take the target R-value of 38 and divide it by the R-factor of 3.1:

R-value needed / R-factor per inch = Inches of insulation needed

38 / 3.1 ≈ 12.26

Since insulation is typically measured in whole inches, you would round this number up to the nearest whole inch, which gives you 12 inches. This calculation shows that 12 inches of brown cellulose insulation is necessary to achieve the desired R38 rating, making it the correct choice.

Other options present numbers outside of the calculated inches required, which would either result in insufficient insulation (lower R-value) or excessive insulation that goes beyond what is necessary to reach R38.