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

To determine how many inches of brown cellulose insulation are required to achieve an R-value of R38, given that the insulation has an R-factor of 3.1 per inch, you need to divide the desired R-value by the R-factor per inch.

Starting with the formula:

Required inches of insulation = Desired R-value / R-factor per inch.

Substituting in the values, we have:

Required inches of insulation = 38 / 3.1.

When you perform that calculation:

38 ÷ 3.1 = approximately 12.26 inches.

Given that insulation thickness is generally measured in whole inches, you would round this to 12 inches.

This means that to achieve an R-value of R38 with brown cellulose insulation, you would need about 12 inches of insulation. This aligns with the correct answer, which accurately reflects the calculations based on the given R-factor.

Knowing how to calculate the thickness of insulation required for specific R-values is essential, as it ensures that the building meets energy efficiency standards. This understanding helps in making informed decisions about insulation materials and their application in construction projects.