hey yall question for insulation

[Schoolhouse mama]

so i am looking through trying to find decent r values in foam board insulation, and I can get an r10 and double it. I have called around to about 6 places for spray closed cell insulation and they are wanting to charge me 1200 for my 150 sq ft space. So, because my hubby can't regulate his temp we will stick to the coast quite a bit but definately want to be comfy, we may take off into the mountains in the fall but never winter.

What I am asking
What R value rating should I get for the bus to keep it cool enough.

thanks yall!

[BusFiend]

With or without air conditioning?

R20 would be nice. R13 would suffice.

$1200 for spray insulation is cheap. Most are paying $2000-3000.

[Schoolhouse mama]

Wow for real 2k-3k for spray in geez, we are going to have AC inside also.

[VeldatheWonderbus]

If you're looking to stay cool, make sure that you paint your bus a light color - white or even silver are best for this. Light colors reflect the most sunlight and will absorb less heat. Since I'm looking to be in the mountains (especially in the winter) we went with a midnight blue paint to make sure we absorb as much heat as possible from the sun. You might also consider using mylar/aluminum coated insulation. You need to keep at least 3/4" of open air space between the shell of the bus and the mylar/aluminum face for this stuff to work, and it doesn't have an "r value", but it reflects up to 90% of heat (R values only describe one kind of heat transfer, but this stuff works really well at stopping heat from passing through when installed correctly).

[BusFiend]

That is the conundrum full-timers are placed in. Do we design for summer or winter? Are we "chasing" 70* temps all year long? I think I'm designing for hot climates. It's much more difficult and expensive to cool than heat. Anything we can do to ease the cooling load will pay off. Preventing heat transfer through the roof is the goal. That keeps the summer heat out and the winter heat in. I'm shooting for an R24 in the ceiling.

Has anyone tried the automotive spray treatment? It's supposed to greatly reduce heat transfer. I'll see if I can find the YT demo again.