The first step in any successful project is making sure you know what you are setting out to accomplish. For metal
ducts that are “sweating”, a 1” layer of cured closed-cell foam will prevent that condensation from forming. Wrap
insulation isn’t as effective as spray foam as foam will bond to the surface, eliminating that little bit of empty
space where future condensation can occur.


Your total required number of spray foam kits is determined by your total board-feet need. A board-foot is
one squared foot at one inch thick. With a duct, it’s usually easiest to round up to the next half or whole number when calculating and keep it in terms of feet. Trying to do the math using inches makes it overly complicated. For
example, a duct run that is 16”X16” and 150 feet long, if doing all four sides would be 1.5’ X 4 sides = 6 feet
around. 6’ around X 150 feet long is 900 squared feet. Add about 10% or so for waste. Divide your total board-feet
need by 600 (the board-feet a Foam it Green 602 kit can cover), round it up to the next whole kit, and place your


It’s difficult if not impossible to get foam off of surfaces it hits. So, be sure to take the time to cover anything you do
not want foam stuck to including floors, windows, equipment in the area, and even you once you start
spraying! Along with the recommended PPE, the sprayer should have no exposed skin or hair during application.
How do you get foam out of a beard? In a word, scissors. As always, make sure your target spray surfaces measure
between 65F-85F, so with air conditioning ducts, they should be off for long enough to get up to this
temperature. The foam can be painted when done, and a latex based paint is usually the best way to go. Foam it
Green is ASTM E84 Class 1 Fire-retardant insulation.


Target a wet foam application thickness of 1/3” as that will expand to one inch cured. When spraying overhead, it’s
recommended to leave off the fan spray tip and simply use the mixing nozzle alone. Get your hand a bit closer when
pointing up, and use a lighter trigger pull so you don’t “bounce” the foam off the surface.

Our Recommendation

Standard Closed Cell Spray Foam!

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