In article ,
said...
A guy at Owens-Corning 1-800-get-pink told me not to insulate an unheated
and uncooled space like a garage, and maybe like your porch, because natural
"breathing" is hindered and the room stays uncomfortable and possibly
stinky/moldy. Normal walls are not vented. Existing techniques are tried and
true, and I don't think you should invent a new method of building.

I have my garage insulated so that I can run a heater in the winter when I
want to. It doesn't get that musty because the doors are open often
enough.

Still, in this guy's situation it sounds like he knows he's going to have
moisture so he should probably not insulate or even close up the walls
until the moisture source is blockable.