Calculating Board Feet with Spray Foam Insulation

When applying spray foam insulation it will tell you how much board feet it covers. e.g. two part foam kit for 200 board foot. What does that mean exactly? Will it cover 200 feet? How do you calculate how much you would need for you job?

Board Feet has it’s origins in the lumber industry- it is a calculation of lumber volume. So 1 board foot would cover a square 1 foot by 1 foot by 1 inch.

So 200 board foot spray foam insulation kit would cover 200 squares that are 1 foot by 1 foot by 1 inch. Now suppose you want to calculate how many two part foam spray kits you would need to cover 400 square feet. The first thing you need to determine is the level of thickness. So say you want to spray it on 2 inches thick.

So you would need four 200 board feet spray foam insulation kits- here’s the calculation:

• two 200 board feet kits will cover 400 sq feet 1 inch thick. For 2 inches thick you double the quantity.

That is the minimum you would need and to be on the safe side- maybe add another kit because spray foam kits give the board feet coverage under optimum circumstances such as:

1. applicator is a pro and knows how to apply it perfectly
2. the temperature is warm

Given that won’t always be the case, it’s better to get a little bit extra to cover the entire area properly.