Measure the largest window first to determine whether the square footage is over or under 12.5. If it is under, you don’t have to measure the rest 🙂
What you need to know before you start:
How many windows on each floor? Measure the length and width of each window. Then multiply those two numbers to get the square footage.
How many windows on each floor?
1st Floor: Windows up to 10′ high
2nd Floor: Windows up to 20′ high
3rd Floor: Windows up to 28′ high
Glass doors are treated as windows
Do they have grilles or divided lites? Divided lites are multiple panes of glass separated by wood or metal. Grilles are mounted over the glass surface.