Calculate the Rvalue for a similar wall construction as show

Calculate the R-value for a similar wall construction as shown in the figure and described below:

1: Outside Surface (15mph wind) 2: Wood Siding 3: Sheathing 4: Insulation Area 5: Nominal 2\"x4\" Wood Studs 6: Gypsum Board 7: Inside Surface (Still Air) R = 0.17 R = 0.81 R 1.32 R=11.00 R = 4.35 R = 0.45 R = 0.68 2 3 45 6 7 i) Calculate the R-Value for the wall above assuming it is infinitely tall and the i) Revise the wall to 2x6 stud construction with studs on 20\" centers and the use ii) Add a 2\" polystyrene layer to the exterior of the wall of part ii). (Document the wood studs are installed on 16\" centers of R18 batts source of your information on polystyrene material properties)

Solution

1) the total r value of the composite materials in the wall

=0.17 +0.81 + 1.32 + 11 +4.35 + 0.45 +0.68

= 19.32

2) by using 2x6 wood studs and R18 butts, the r value becomes 6.88

So the total r value becomes 21.82

3) 2\" of polystyrene at 5 per inch will have an R value of 10

So total R value becomes 29.32