Insulation, Radiant and Vapor Barriers - painted block garage wall

I am insulating my detached, one car, cement block garage for use as a workshop. I live in eastern PA so year round temps can vary.

The outside walls have foam board under vinyl siding on three sides and brick on the front. I have installed an insulated garage door, a good quality double pane window, and I have painted the interior with a waterproofing paint.

To save space I would like to use foam board insulation instead of framing out the walls. Is the paint enough of a moisture barrier? Is is okay to install insulation board against the painted block?

Thanks.

Are you planning to cover the foam board? Typically exposed foam board inside violates firecode: it needs to be covered with sheet rock.

Hi sorry for the delayed response. Actually you have asked the question that I am now looking into. Do you know if there is foam board insulation product that does not require the additional layer of drywall? I am also planning to remodel my basement and this would be useful there as well.
Thanks. Al

It am not aware of any that has IRC approval.

You will need a non-combustible covering (typically drywall).

If you have any questions about the "waterproof" paint, do not even consider fiberglass. It just hold too much moisture, is ineffective if it has any moisture and does not dry out in place.

For the garage, you could use 2x2s @16" or 24" with rigid extruded polystyrene insulation in between to save space.

Dick

I am looking into using an extruded polystyrene Owens Corning product that you can attach using furring strips. Then cover with fire rated drywall.

Do you know what is used by the Owens Corning basement finishing system? I had called OC but they are keeping it a secret.

Thanks,
Al