First, your location is very important on whether you have predominantly heating days or cooling days. But on a detached garage, it may not be as critical with all the air infiltration anyways.
For a radiant barrier to work it requires an air space (start at 3/4" min) right next to it. Putting the face on the inside makes it a little hard if you are insulating the walls, especially a 2x4 thickness. In this respect you get more out of insulation and airsealing than you do a radiant barrier. Hopefully you didn't pay a premium for the OSB.
If you now decide to leave the insulation out, you would retain the benefits of the radiant barrier, but in a garage you are not measuring that benefit on a conditioned space (like in rooms below an attic), but rather on the objects stored in the garage.
If you had put the foil facing out, like is commonly done in hot regions, then you install furring over that to create the airspace.
Check your product being faced to the inside: If the foil is perforated for moisture, then it probably won't hurt to have a housewrap installed. If the foil is non-perforated (where you also tape all the seams and it is marketed as a barrier to replace housewrap), then you might have problems with condensation behind the insulation (although unconditioned airy garage may not see those conditions often).
For a radiant barrier to work it requires an air space (start at 3/4" min) right next to it. Putting the face on the inside makes it a little hard if you are insulating the walls, especially a 2x4 thickness. In this respect you get more out of insulation and airsealing than you do a radiant barrier. Hopefully you didn't pay a premium for the OSB.
If you now decide to leave the insulation out, you would retain the benefits of the radiant barrier, but in a garage you are not measuring that benefit on a conditioned space (like in rooms below an attic), but rather on the objects stored in the garage.
If you had put the foil facing out, like is commonly done in hot regions, then you install furring over that to create the airspace.
Check your product being faced to the inside: If the foil is perforated for moisture, then it probably won't hurt to have a housewrap installed. If the foil is non-perforated (where you also tape all the seams and it is marketed as a barrier to replace housewrap), then you might have problems with condensation behind the insulation (although unconditioned airy garage may not see those conditions often).
