Part 3 - Applying DIY Spray Foam Insulation


1. Wear a respirator with cartridges and filters rated for the kit foam you are going to use (ask the manufacturer), safety glasses, coveralls, and disposable gloves. New foam is super sticky and will stick to cloths permanently. Also, have a container of Vaseline to dip your mixers in.

2. Have a large trash bag available for making test shots of the foam to periodically check to make sure you are still making good foam. If a valve is clogged or a mixer is bad you could be making bad foam and you won't know it until it is too late. This may seem like a waste of foam but it is not as much of a waste as bad foam being in your walls. If your test bag is more than halfway full get a new one, heat will build up in the thick pile of foam and could melt the bag.

3. Change or test the mixer on the foam gun (with a test shot in the bag) after every 30-60 seconds without being used. If the mixer is ever suspect switch to a new one. Dip the back (the side that plugs into the gun) of each new mixer in Vaseline before replacing, this will help keep the gun head clean. When you are done using the kit for a while leave the last mixer on the gun and start with fresh mixer the next time you use the kit. Have spare mixers available where you are working.

4. Store the kit in warm dry place that will maintain the canisters between 70-80 F (21-27 C).

5. Make sure the surface you will be spraying on is dry and at least 50 F (10 C) during the time of application and for at least 24 hours afterwards.

6. Mask around the area you are going to spray. Clear the area of any and all valuables. Mask nearby electrical outlets, switches, breaker boxes. Kit foam will create overspray that sticks tenaciously to everything.

7. Plan your application so you can spray long shots of foam at once with minimal waiting while you position for a new shot, this will reduce the number of times you have to change the mixer. Always do test shots into the trash bag and wait to see how the foam rises if the gun has been sitting for more than 60 seconds.

8. Avoid doing low velocity, detailed foam sealing with kit foam (i.e. sealing narrow gaps or around window frames). Chemicals that go too slowly though the mixer will clog the mixer and make bad foam. One-part can foam, also called gun foam, is much better for detailed air sealing.

9. Swirl the tanks every so often while foaming to make sure the chemicals don't stratify in the tanks.

10. Apply the foam in layers no thicker than 2" at a time. On really hot surfaces 100 F (38 C) or more you may not want to spray. The underside of a roof on a summer day can easily reach 100 F or more. There are advanced procedures that allow you to spray on surfaces that are too hot or too cold but those are beyond the DIY realm.

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Return to Part 1 - Purchasing DIY Spray Foam Insulation

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