Preventing mold in new screen porch

[thuff]

We have just built a new screen porch. I am in the process of insulating the walls so next few years I can replace all the screen windows with true storm windows. But this is the problem I am running into, I want to prevent the water from running down the inside of the wall and getting the rigid foam insulation wet. Also if I vent the bottom of the wall where the tongue and groove is going on the interior walls will this prevent mold from growing inside the wall cavities? Or I am going to get mold even without venting it?

[B]

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.

[Brad]

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.