The county inspector visited and recommended - not insisting - that we
insulate an old walk in.
He suggested using R25 foam boards on the walls and then covering it
with FRP.

Does that sound reasonable?
What kind of glue could we use?
How long once we take the food out do we need to let the walk in get to
room temp? (one day? two days? more?)
Any other ideas on accomplishing this task?

Thanks for any ideas anyone might have.

Mike

PS: If you are in the San Francisco Bay Area and might want to tackle
this, I would like to talk to you.
(My current plan is to have my part time handyman do the job.)