Hey folks! Thanks in advance for any advice and/or help on this matter.

I'm currently working on a renovation project in my sun room. I live in a 1939 brick cape cod and am working on an addition (I suspect it was done in the 70s) that is made of cinder block on concrete slab and the dreaded flat roof. I had the roof redone a couple of years ago and am finally getting around to finishing this thing up.

Basically I have stripped everything down to the studs (they aren't really studs but rather 3/4 in boards leveled and nailed into the cinder block) and am wondering how to insulate this bad boy. I think I want to use 1/2 inch (this fits with the current wall structure) R-matte plus 3 insulation. I got a 4x8 piece to test out and it's easy enough to cut and fit into the wall sections. There is only a small gap between the cinder block and the edge of the studs. After insulating I am doing pallet walls on three of the 4 walls, the fourth will be exposed brick. The room has no insulation and I figured something was better than nothing.

I will not be insulating the ceiling and will infact be keeping it exposed for both esthetics and ease at this juncture in the game. I'm aware I won't be getting the best bang for my buck but this is where I'm at. It's possible I will decide to put a hard ceiling in later on which is why I want to insulate the walls now just incase.

Will the r-matte work? Will an adhesive be enough to stick them to the wall prior to nailing in the pallet sections? Do I need a vapor barrier/thermal barrier? Lastly I need to put the foil side towards the outside and not the inside correct?

I hope I explained this well enough. Our goal here is to have a rustic feel in the sun room which is why we are doing pallet walls. I want to at least attempt to do the best I can in terms of insulating while I can. I'm open to other suggestions and again I appreciate anyone's advice!