How to Measure Walls for Insulation
Measure each wall section separately, calculate its gross area, subtract openings where appropriate, then add the net areas together.
Step 1: measure wall width and height
For a rectangular wall, area = width × height. Keep all measurements in the same unit before multiplying.
Step 2: subtract openings
Measure doors, windows or other areas that will not be insulated and subtract those areas from the gross wall area. If small openings still create cutting waste, keep the waste allowance separate rather than hiding it inside the measured area.
Step 3: combine wall sections
For rooms, extensions or mixed wall sections, calculate each section independently and total the net areas. The Insulation Multi-Area Planner can combine wall, floor and ceiling areas before package rounding.
Step 4: apply product coverage
Once you have the net area, use the coverage stated for the exact insulation product and then add a visible allowance for cuts or project conditions.