Revised :
With little real information to go on. The only info I could get from the manufacturer (LP) is to leave a 3/4 air gap. That's come a little late because I had to keep moving forward.
So - what I've actually done.
North wall. Little to no direct sunlight. Rockwool filling between studs > 7/16 OSB. That's it.
South Wall. 50% direct sunlight. Added 1" strip of wood to front faces of studs. Filled cavity flush to front with Rockwool. Achieved a 1" air gap to radiant barrier. And will cover with 7/16 OSB.
Going vapor barrier free - in hopes that the walls can still "breath" as needed year round.
The roof I am going to bite the bullet and do foam board + spray foam between the joists.
Guess I will find out in a few years if this is a total disaster.
I have spent hours trying to figure this one out. I have a new detached garage on concrete slab floor. The building was installed by tuff shed. There is a silver radiant barrier on all the walls and the roof.
Step 1. How to insulate the walls?
The walls themselves dont get that match direct sunlight - so I am thinking of sacrificing the radiant quality and putting insulation right on the surface. Ie no air gap. Total mistake?
The current idea:
Inside = 7/16 OSB > Insulation R15 Rockwool (between studs)> Exterior wall
Garage will be heated and cooled. Located in Colorado Zone 5.
The main questions are:
does there need to be a vapor barrier? Or Vapor Retarder? And if so - where?
should I put in a spacer to hold off the Rockwool from direct contact with the silver? If so - does that space need a way to vent?
If Rockwool is the wrong material - boards are an option also. But seem much more labor intensive spray foaming all the edges and offer lesser R value. And again the questions about keeping a 1-inch air gap or going flush against the backing are still in play.
Step 2: The Roof. Which I am saving for another day....
Thank you!
