Insulation, Radiant and Vapor Barriers - XPS against wall with french drain/floating slab

http://i897.photobucket.com/albums/ac177/Skoorb100/insulation.jpg
http://i897.photobucket.com/albums/ac177/Skoorb100/insulation.jpg

I am putting some XPS insulation against my wall. I have that french drain situation at the bottom. I had planned to leave a thin vertical distance between the bottom of the foam and the slab, is this best?

Also, can anybody recommend a best-brand construction adhesive to attach this to the wall? I want to avoid mechanical fasteners because I think glue is quicker and will be seamless. Is it going to hold up in the moist environment of a wall for years and years?

I've used liquid nails or construction adhesive, but check to see if they say anything about moisture. The issue with glue is you have to hold it in place until the glue drys. Adding a few fasteners and some straps might be best, at least until it dries. You also need to cover it with something to meet fire codes.
Here are a couple of links for reading: Wet Wall Proposal (http://www.buildingfoundation.umn.edu/WetWallProposal/WetWallProp.htm)
RR-0509c: Renovating Existing Basements — (http://www.buildingscience.com/documents/reports/rr-0509c-renovating-existing-basements/view?searchterm=basement)

Bud

Yeah I think you're probably right, just a couple of furring strips vertical near the middle few feet so that I can still have the stud wall flush with the foam. Speaking of which, if you've come upon any recommendation on whether studs should be against the foam or not, let me know. The foam is very minorly able to move moisture so I'm thinking have the studs stand off just a 1/4" or something to avoid wicking minor amounts of moisture into the wood.

I've seen the buildingscience link you sent but will now read the other one.

BTW what tape do you use and when you use adhesive do you glue the foam's joints together, too? Seems expensive, though.

I'm going to avoid S pattern of glue and instead go vertical so that there are some channels on the back to drain any water.

Most construction adhesives will eat XPS foam. You will want to use foamboard adhesive. PL300 / Liquid Nails foamboard adhesive / Powergrab foamboard adhesive, or similar. You will likely need a few fasteners unless you plan to brace the sheets to the wall until the adhesive sets up.

I've started applying, going with the PL300. The stuff is crazy expensive, though. It's $3.50 for a 10oz tube and it's easy enough to go through a tube for only two 2' sheets, so we're talking $100 in adhesive for a basement if really done thoroughly, Liquid Nails heavy duty I've not tried yet but it says it's safe for polystyrene. It's also cheaper and much easier to get in 28oz tubes.

The cheapest, and in fact quickest, would be tapcons but it's hard to find large washers with thin holes that are also sufficiently weatherized, plus I wonder if the tapcon would get cold from being in contact with the brick and provide a small area for condensation.

Question, what are you putting over that polystyrene? You might have said and I missed it. But it needs a fire barrier, like 1/2" drywall.

And you are correct, the 28 oz tubes will be a better price. Besides you won't have to reload every time you turn around.

Bud

Question, what are you putting over that polystyrene? You might have said and I missed it. But it needs a fire barrier, like 1/2" drywall.

And you are correct, the 28 oz tubes will be a better price. Besides you won't have to reload every time you turn around.

BudIt will be exposed until I drywall it as part of the finishing during the first half of next year. I had not intended on covering the band joist or rim joist areas directly with anything. I don't know if I need to have drywall specifically up against them or whether the envelope of the rest of the room (drywall wall and ceiling) will be sufficient but if the inspector makes me drywall the joist bays now that I've rigid foam + great stuffed them, I'll do it.