I am hoping to get some advice from the collective brain here about insulation. A couple of local people have spoken to me recently about the value and benefits of closed cell spray foam for the 100 year old 900 square foot house I am working on. There is a local guy who has a spray foam business who came out to measure and make a quote on Friday. It would be $11,660 to do the whole house, including the walls, the kitchen roof, the main house attic, the sill/rim joist area and the basement walls down to frost line. The alternative is to put loose fill in the attic floor, rockwool in the walls and kitchen roof, and not worry about the basement for now. I have not run the numbers at current prices but I would guess I'd be looking at $2-4,000 or so if I do that myself. Primary heat will be a wood stove, with a mini split for backup/shoulder seasons. The climate is quite cold, a solid Zone 4 agriculturally.
One thing that surprised me was that he recommended spraying the underside of the roof and the gable ends in the attic, so it would not be insulated off from the rest of the space. He said it would be more efficient because it would keep the heat and cold further away from the actual living space. I am planning to put a floor in the attic and use it for storage.
I forgot to add: the quote is itemized so I can get some things spray foamed and do other things myself if I want to do it that way.
If anyone has any advice about what to do I would be grateful to hear it. I don't have to decide right now, but will need to in the next 2-3 weeks to keep things on schedule. Spray foam is a lot of money, but some people seem to think it is really a lot more efficient and effective and I can afford to do it if it is really that much better.