Come to think of it thats exactley where I have seen it on ducting. I agree with you about the wall but I was thinking of using it to cover my veg cab.if it is what i think you are describing, i use it to seal my ductwork and repair holes, etc.. but by the time you covered a wall with it - it would probably be MUCH cheaper to just use mylar.
Thanks I might go pick up a roll try it out.i like it - it is very sticky, stiff, and strong and tears easier than duct tape.