Insulation Rolls: Counting Rolls Around Obstacles
Joists, pipes, and wiring all create trimming waste. A 10 percent allowance keeps the coverage continuous instead of patchy.
What is the Insulation Rolls Calculator?
Enter the area to insulate and the coverage of one roll, and the tool adds a 10 percent allowance for trimming around joists, pipes, and edges before rounding up. The allowance is shown separately from the exact roll count.
How to use it
- Measure the area in square metres.
- Enter the coverage of one roll.
- Click Count Rolls.
Worked example
50 sq m at 10 sq m per roll needs 5 rolls exactly, or 5.5 with waste, rounded up to 6 rolls.
Should I compress insulation to fit?
No. Compressing it reduces its insulating value, so cut it to fit loosely instead of squashing it in.
Frequently asked questions
Does roll width matter?
Yes, matching roll width to joist spacing reduces cutting and waste.
What about double layers?
Double the area figure first if you plan two layers, then apply the allowance.