After having witnessed the closed cell installation, I was sure that the spraying of the open cell foam would be pretty straightforward. Not so! It actually is quite challenging.
If you look at the expansion rate of the liquid into foam, you may understand why I was so eager to get the three inch thermal break gap plugged. Same for the drywall we put around the window and door openings.
I knew that the listed expansion rate for the open cell foam is 1 in 100. But seeing it grow, expand and spread out into every little space is something else.
Because of the high expansion rate, it is rather difficult to consistently apply a two inch layer on the wall. Over spraying happened quite a bit, which resulted in a layer thicker than two inches; sometimes filling the entire wall framing.
The ceiling was easier. Here we specified a three inch application to air seal the space between the garden unit and first floor. In addition to the air seal, the open cell foam also reduces noise transfer between the two living spaces.
Here are some of the basic specifications for the open cell foam: