What size of insulation goes on top of double layer to make 6" x 4" if the first layer is 6" x 2"?

• A. 8" x 2"
• B. 9" x 2"
• C. 10" x 2"
• D. 12" x 2"

Answer: (C)

To get a final size of 6" by 4" from a first layer of 6" by 2", you’re expanding the second dimension (the width) from 2" to 4" while keeping the other dimension (the length) at 6". The top layer needs to have the same width (2") and be long enough to accommodate that layout so the overall footprint becomes 6" by 4". Among the given options, the piece that fits this arrangement is 10" long by 2" wide. So the top layer should be 10" x 2".