Some ceramic coatings feature additional properties, like preventing moisture migration. Some structures see up to 25 percent of HVAC costs coming from dehumidification needs, but a ceramic coating can also bring savings through moisture management. Additional features can include mold and mildew control, sound attenuation properties, and fire resistance. Spray Coating
You want to know when the job has been done well and when it didn't go as expected. You take accountability for your actions and understand that in business, results matter more than intentions. As empowered decision makers, PPG Coatings Services team members take pride in their ability to help customers overcome their toughest challenges, while sharing in the rewards and satisfaction that come with a job well done.
This is more common with closed cell foam, but it happens with open cell foam, too. Since closed cell foam has a higher R-value per inch, installers generally spray 2" in walls and 3" in rooflines to meet the energy code requirements of R-13 and R-19, respectively. (I'm not going to dive into the energy code here, but these numbers apply to many climate zones, the latter being allowed under the UA tradeoffs rule. See the Energy Nerd's blog on this topic if you want to argue.) Spray Coating Services
Steve: If your spray foam installer leaves the vents open, he will be committing the 2nd of the 4 problems I described above. You will most likely have comfort and efficiency problems. You may well have condensation problems. You will be spending a lot of money on a product that likely won't perform as it should. Don't let him leave the vents open. If the installer you've chosen doesn't understand this, you may want to choose someone else. 
As this example illustrates, it's important to seal the envelope completely. One of spray foam's biggest selling points is its air-sealing ability, but it can't seal places where it's not sprayed. One of the nice things about using spray foam in new construction is that you can do a Blower Door test before the drywall goes in. Even better, you can test for leaks with a fog machine. Spray Coating