Thank you, Perpetual,for taking the time to comment.
The renovated attic space will retain vaulted ceilings.
Respectfully, I chuckled at your belief that my concerns about contractor wordsmithing are unfounded. Not trying to be a wise guy, but here's why I say this:
Today, I visited my Building Inspector here in Connecticut.
I was shocked when he said that he would reject any open cell foam contractor proposal or work that did not first establish an eave/soffitt -to-ridge vent system to achieve a ventillated airspace, thus creating air movement between the open cell foam and the roof deck.
This completely challenges two open cell contractors' proposals to spray directly to the roof deck, and in addition, seal off all eave/soffitt/ridge vents completely.
I don't know who to believe, the contractors or the town! Furthermore, once sprayed, I don't know how he would inspect to even determine the existence of deck ventillation. My hunch is that no-one in my town must be taking out permits, because I know for a fact that open cell guys are spraying directly to the roof deck all over the place.
He did confirmed that Vapor barrier is required over open cell, followed by 20 second block such as 1/2" sheetrock. I was delighted to hear him state that it was ok to also use architectural hardwood veneer panels using 1/2" mdf, or even some mteallic radiant wrap materials.
Now, I never intended to spring for a total closed cell job.
To offset the cost of closed cell, I was investigating flash & batt, using just 1 or 2" of closed cell, followed by fiberglass. The inspector recommended this approach and indicated that a vapor barrier would then be unnecessary because it was already achieved by the closed cell attached directly to the roof deck.
Furthermore, he stated that concerns about closed cell "shrinking", "not-adhering" or "breaking free" can happen, due poor applicator skill (not deficient product) and that it mostly affect the rafters and studs, not the roof deck. He concluded that these problems always show up at inspection.....not down the road. 'Not sure I buy that one either.
Since the plan calls for vaulted ceilings, I was told that meeting the required R-18 overall forces me to complete a REScheck Compliannce Certificate from www.Energycodes.gov.
I plan to throw that one at the contractors.
So, is Mass similar to CT in these regards?