How many samples are required for 38 LF of TSI?

• A. 3
• B. 2
• C. 4
• D. 5

Answer: (A)

For thermal system insulation, you collect 3 bulk samples for every 40 linear feet of TSI, or any portion of that 40-foot block. This knob helps ensure the samples represent possible variations along the run. Since 38 feet falls within the first 40-foot block, 3 samples are required. If the length were longer than 40 feet, you’d add additional sets of 3 samples for each subsequent 40-foot block (e.g., 41–80 feet would require 6 samples).