I presume that the plumbing and HVAC are going parallel to the wall. Are they at the ceiling or partway down? You may be able to build a soffit if the obstructions are near the ceiling. If going vertical then enclose within the wall. I believe I would attach XPS to the concrete foundation which would fill 2" of the 4" gap you're now anticipating. Your greatest need, being that your are in the Pacific NW, is to control the humidity year 'round. A good dehumidifier in your case would be a priority no matter how you insulate.

We are remodeling master bath in FL house--concrete block exterior and bath has three sides on exterior corner-- shower and tub are coming out--and adding larger 4x6 shower on wall where tub is now... contractor who will likely do the job (can't get anyone else to follow through) sent initial scope of work today-- doesn't mention adding any insulation to walls where shower and tub are coming out-- doesn't mention any weather stripping/insulation around window that is in current shower stall...we are taking out existing linen closet on that wall beside shower that is coming out--replacing with larger linen closet and some cabinets under the window--so new dry wall will be needed in some areas... I think this window which was changed out for original several years ago by other owners might be part of reason there is water damage behind tiles in shower... DO these concrete block homes have insulation--there is only a very shallow build out with flat firring stips behind the sheetrock now from what I understand-- if you can't do real insulation, should there be a vapor barrier? nothing like that was mentioned in the scope of work...although he will use a vinyl membrane in the shower stall...

no. put the 1st layer xps between furring strips already there. then put another 2nd layer that will cover both the layer of xps against the block & furring strips. when installing drywall use longer screws and screw thru drywall, top layer of xps & into furring strips. then you'll have the layer against the wall installed inbetween strips, and another layer of 3/4" xps on top. this will give you as much as in basement. not suprised you didn't find R-value. tj..for my radiant barrier in the attic..where the work in hot climates, I paid .05 per sq ft. single sided fsk radiant barrier. this is my material of choice. not much sense in paying more for a more expensive product that works just the same as single sided product. what sells the more expensive product is hype. I'm very pleased with radiant barrier in attic in my hot climate. reflects the heat nicely the actual insulation on the floor of the attic is what keeps attic temps in the attic. not the radiant barrier. the radiant barrier has minimal R-value. its value is in emissivity. even with 4'x8' sheets of iso board ( R-7 foam with foil facing) I can cut with no waste. tape measure, tsquare razor knife. no problem. oh and I get actual R-VALUE. Double-bubble stacked x3 with 1/2" air gap = r50. This is FACT. no its sales hype. if you find R-value of foil bubble foil wrap..please post it. just not from mfg selling the product, a site where the info is unbiased. I'm not the only person to know this is true. those scam artists come out every year taking advantage of older people with RB rolled over insulation in attics. scam. scam. scam. http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/29497/The-Foil-Faced-Bubble-Wrap-Sham-Understanding-Radiant-Barriers read the comments Kvalue folks strike again! LOL!

I'm dealing with water issues before doing a complete reno and found that a previously installed interior drainage system was a little lacking. It's not deep enough, not connected correctly to the sump, etc. It DOES have little weep holes drilled in the first course of the block walls on top of the footer. This is below the below the floor surface of the basement slab and was covered by about an inch of lightweight cement prior to me digging it up. This is common thinking for when it was installed in the 70s/80s. I'm wondering if I shouldn't just put hydraulic cement and a capilary break with drylock over them before I close up the old drainage channel with fresh concrete. Alternatively, I could try to dig the whole system down a bit deeper and actually close it in properly so it will actually function as a path to the sump (gravel and XPS or sealed poly barrier under slab, etc.) the only water problems I've had appear to originate from groundwater around the footers permeating up where these very channels had been dug and not moisture in the wall, but that's not to say the're not continually taking on small amounts of water and the weep holes are "helping" a little. All the building science recommendations seem to apply to poured walls that might be saturated with water but not CONTAINING water cavities. I'd like to make a continuous barrier and seal things up but am afraid I'll make things worse if I don't let these old solutions drain to the inside. Anyone done something similar or have experience blending old solutions with more modern techniques? Dan