Sprayed foam insulation is expensive, partly due to the materials, partly the on-site labor. Extruded foam insulation (Styrofoam and the other brands) is also pricey, but you don't have the labor of someone coming to your house to install/spray it. Recommendations for how to insulate basement walls can be found in the technical articles on www.buildingscience.com

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....

I've often written about foam being better than batts. In a concrete basement below grade there will be no air pressure differential to cause air movement from the outside in. Batts are OK here. The bathroom is not going to be sealed from the rest of the house, so whether the batts are faced or not is not a big deal. That is my view. Others may be more precise about reasons for one or the other. Definitely do insulate. It's a more comfortable room afterwards. The temperature gradient is lessened. Batts are OK. Any kind of batt. If you want to do somthing better, you could use spray foam but that is a whole new learning curve. Batts are easy. Methinks a little knowledge can be a dangerous thing.

Sue, I've heard folks tell that it helps to insulate under the floor. But what about insulating down the basement walls to a few feet under grade? That wouldn't take a lot more insulation, and you'd have some more comfortable space in the basement. In summer, I often turn on the furnace fan late in the afternoon when things get rather hot, here north of the southernmost Great Lake (Erie). That blows some rather cool basement air up into the house. We find that in that semi-cool basement in summer the warm air moving down there from outside tends to deposit some moisture and goods made of iron tend to rust. Some papers, etc. tend to mould and there is some on the walls of a finished basement room. Several years ago our local utility added a timer to our water heater that made it run at 2:00 a.m., when there was low demand for power (with an over-ride button that one could push in case of shortage). Plus they added an insulating blanket. When another jurisdiction took over that project, they removed the timers when they made service calls, plus the insulation, when they installed a replacement heater. At least, they were going to, but I told them to leave that blanket right there - which they didn't mind doing. Hope you can make arrangments that keep you and yours as snug as a bug in a rug (or should that be, " ... as snug as bugs in rugs"?). ole joyful P.S. I guess the number of bugs isn't a big deal for you who, like I, live alone. o j