[jimbomaybe]

I have foam board up in garage (have done the doors), I am thinking of using the plastic panels to protect the insulation on the walls, Tapcon w/ finish washers to attach the panels , any better ideas ?

[Dana1963]

There many construction adhesives such as Liquid Nails. Home Depot or Lowe’s

[retiredguy123]

Exterior wall insulation has a vapor barrier on the outside surface to prevent moisture penetration. If you create a second vapor barrier on the inside surface, you could possibly trap moisture between the two vapor barriers. So, if you use plastic panels, I would make sure that you don't sandwich the insulation between two vapor barriers.

[jimbomaybe]

the foam board has a metallic reflective coating/layer that is and should be facing to the outside, the foam board I have installed is on the interior of the masonry block much the same way the rest of the house was done, if moisture get through that I will have bigger problems, but I understand the concern, the new construction has sleepers between the foam board insulation and the drywall that gives an air space between the two, I have wondered about filing that space with insulating pellets ???

[villagetinker]

Jimbomaybe, At this point I am confused by your posts, but here is what I would do:
I would leave the 'space' (second post) and just place the plastic panels on the sleepers.
I would use the tapcon screws you mentioned however yo may need to be careful that you do not crack the plastic.
I would not seal the top or bottom seams of the plastic panels to the floor or ceiling, this would allow some breathing in case there is moisture build up I THINK.
All of this is assuming that you are talking about solid plastic panels. If you are just after a covering, you might look into a perforated panel (like the soffit panels), this would provide covering and allow ventilation for moisture.
You might also check with a home inspector like Frank DeAngelo on the matter to see if something is being missed, and if there are other concerns not being addressed, like recessed outlets, etc.
Good luck with your project.