worthy -- thanks for replying... unfortunately, I can not slide in the XPS behind the studs. By local code, we had to install fire blocking on the end of the wall. So now it is closed off. And, I can't install XPS in between the studs becuase I already have electrical and piping running through the studs. The gap between the wall and the stud is only a little more than 1/2". So even if I could slide in the XPS behind the studs, I would only get about r 3 value.... Thats why I figured it is almost better to put no insulation. The pipes arent gonna freeze; Plus, if I do get moisture back there, then there will be no fiberglass insulation to get wet. With no insulation, the wall will just dry out. (with the help of my dehumidifers and the bathroom vent fan, of course) If I get a chance, I will post a picture tonight of the studded wall with the roughed-in plumbing and electrical. thanks again. mm I'll try to post a picture later....

OK, now I understand. I would use only pressure treated or metal structural support and styrofoam for insulation. Then, green wallboard (moisture resistant). I would install it with screws, but not tape the seams. Cover the seams with a nice piece of wood trim which could easiy be removed accessing the drywall sections. Would only be necessary to locate the screws for the center studs for the section when removing one. As for an entirely removable section, I believe it would be necessary to attach the drywall to plywood or another surface. My concern, based on the conditions you describe, is that the plywood would warp and ruin the wall. Another thought - install a flush door (either hinged or a door panel) where the problem areas need inspection. Hope this helps a bit.

Cute little devils, aren't they? The two inches of mice droppings are actually probably bat guano, not mouse droppings. Very good for the garden, though, full of nitrogen. You can shop vac them up (the droppings, not the bats!) and it will clean up and leave less smell residue than mouse droppings as there is usually less of a bat urine smell (maybe they pee outdoors on the wing), unlike mice who pee where they poop. Once you've got them removed, you'll need to do a meticulous job of re-sealing of even tiny cracks or other bats will find your attic and re-colonize. So, before they are removed study the exterior well to see where they are entering; this is best done in the evening and very early morning when they are returning from a night's bug-catching. But you will have to look for alternate holes as well, as they are really fixated on their roosts and return year after year to the same ones. Depending on where you are, you can also just wait for them to leave for their winter hibernation dens, then seal the walls up to prevent them from coming back next spring. That would save the cost of a bat-removal. Another thing you might do is provide some bright lighting to the area at night through sunrise. Bats like to sleep in the dark and you might discourage them from coming in to roost. But make sure it's safe lighting that won't cause a fire. Bats eats zillions of biting bugs every night, so removing a large colony will change the bug dynamics at your place. But on the other side of the coin, bats can be vectors for rabies, and it is possible for sleeping people (especially young children) to have contact with rabid bats and not realize it until too late. If you should find a dead bat in a sleeping room, contact your doctor and health department immediately. On the whole, bats are nice, useful, critters. I have tons of them in my barns, and even my attics. (I reluctantly tolerate them there, but would rather they stayed in the barn.) They all fly off somewhere for the winter; I'm not sure how I would feel if they were around 12 months of the year. After all the bats are gone, you can look and see if any insulation must be replaced. The good thing about bats is that the dropping piles are usually fairly concentrated so you won't have much too much to do. There are some great books on bats. Looking at pictures of them will scare the bejabbers out of you, though. I lived for many years in areas with large (14" wingspan) fruit-eating bats and medium sized vampire (biting) bats, so the much smaller ones in North America seem pretty tame. Though I hate having one flying around in the house! Just keep thinking of the thousands of mosquitos and black flies and biting gnats they eat every night.....! It's surprising you had two inches of droppings, that takes awhile to accumulate. Fifty years ago, when I was a young girl, my family spent a fair amount of time at Angkor Wat in Cambodia. In those days it wasn't a big, international tourist attraction and one could wander pretty much at will through the various temples. My sister and I sometimes clambered up over piles of bat dung a yard or more high to get into some of the buildings. Now that's a LOT of bat poop! And man, did it stink in that heat....! Molly~

Yes, it appears to be glazed structural terra cotta. In that case, you don't want to anchor anything to the walls as it's a fragile material. So you could use closed-cell spray foam to the desired R Value. Or just an inch or so depending on your climate, followed by fibrous insulation between wood or light steel framing. You might want to have the wall inspected first by a qualified expert as the blocks are usually cited as having a 75-year lifespan.