@nprofile1q... No, we need less ventilation. Since the vapor barrier is between the inside and outside layers of insulation, there should never be a big enough temperature difference at that point to cause condensation.

@nprofile1q... He does not look like he is enjoying the zoom meeting.

Further muddying the environmental calculus of this project, the insulators left the yard covered in tiny bits of foam from the process of cutting the panels, so I am out vacuuming my front lawn and shrubbery like a crazy person.

I'm not sure I've ever felt more #OCPD.

@nprofile1q... Luckily, the 9 inches of insulation should dampen the racket a good bit.

It seems like so much material, but the engineer did the calculations, and six inches of rigid foam, along with sheet metal roofing and solar cells (eventually) are actually less weight than traditional asphalt shingle roofing, so no structural changes were needed. And unlike shingle roofs, it should never wear out or need to be replaced.

Rigid foam insulation is an expensive choice, and I have no idea if it will ever pay for itself or how long it will take.

A lot of the cost seems to be that it is a very uncommon method for residential structures. The insulators were just saying that they never do this sort of thing, and were just doing their best to figure it out.

However, this seems like the most practical solution for insulating old homes with shallow rafters, so here's hoping it is just their first of many such projects.