Which insulation value set is correct according to the standards given?

Which insulation value set is correct according to the standards given?

• A. R12 for 2x6, R20 for 2x4, R30 blown in
• B. R20 for 2x6, R12 for 2x4, R40 blown in
• C. R24 for 2x6, R16 for 2x4, R50 blown in
• D. R22 for 2x6, R14 for 2x4, R35 blown in

Answer: (B)

The main idea is applying the prescribed insulation values for each part of the building envelope: the wall cavities for different stud sizes and the attic insulation when blown-in. The standard in your study sets R20 for a 2x6 wall cavity, R12 for a 2x4 wall cavity, and R40 for attic blown-in insulation. This aligns with how deeper wall cavities (2x6) can carry more insulation, but the standard caps that specific cavity at R20, while 2x4 walls typically use a lower cavity value (R12). Attic insulation often aims for a high value because it’s a large, open boundary, and blown-in insulation can efficiently achieve around R40. The other options mix values that don’t fit these assumed minimums: some use too low or too high attic values, or mismatched wall cavity values for the given stud sizes. So the set that matches R20 for 2x6, R12 for 2x4, and R40 blown-in best satisfies the standard.

The main idea is applying the prescribed insulation values for each part of the building envelope: the wall cavities for different stud sizes and the attic insulation when blown-in. The standard in your study sets R20 for a 2x6 wall cavity, R12 for a 2x4 wall cavity, and R40 for attic blown-in insulation. This aligns with how deeper wall cavities (2x6) can carry more insulation, but the standard caps that specific cavity at R20, while 2x4 walls typically use a lower cavity value (R12). Attic insulation often aims for a high value because it’s a large, open boundary, and blown-in insulation can efficiently achieve around R40.

The other options mix values that don’t fit these assumed minimums: some use too low or too high attic values, or mismatched wall cavity values for the given stud sizes. So the set that matches R20 for 2x6, R12 for 2x4, and R40 blown-in best satisfies the standard.