I think a router might do a good job for a channel for the wire. You could tapcon a wood block on the foam for the electrical boxes.

I'm slowly doing my basement and put one layer of 2" foam with 1x2 furring strips. Now, I had the bright idea of putting another 2" layer of foam on top of that by cutting channels in the new layer to fit over the furring strips. I've done about 5 so far with the router and it seems to be working okay. I've switched over to insulating the rim joints, so that's what I'm doing now.

I'm not even sure how well the dens armor plus drywall I got will mount to the wall. I'm hoping for the best.

Here is a link to a pic of the first layer:
http://farm4.static.flickr.com/3200/2973454464_840a53d356.jpg?v=0

Did you use the preslotted XPS like HD sells,ie your fur strips are flush with the pink board. I can not tell by the photos? Also, if that is how you did it, would you just mount a shallow outlet box to the fir strip? Would 5/8" drywall then cover the box or would it still stick out?

It is 2" unslotted.
I think it's likely recesses would have to be made for boxes and wire.
Why 5/8"?

I thought 5/8 would cover a shallow outlet box mounted on the fir strip. Then again there is the wire to deal with. I think that is the negative to using the XPS w/out framing in front....running the wiring.

I think that is the negative to using the XPS w/out framing in front....running the wiring.

Yep. As well, some jurisdictions may require armoured cable (BX). Until a few years ago, shallow boxes were prohibited here--though you could buy them everywhere.

velvetfoot's installation looks great. Though if he's adding another layer of XPS, it would have been a whole lot simpler and cheaper to put XPS on the walls directly, then conventionally frame and fill with fg.

I like the router method. I can router a pocket 3/4" dp for the box and a channel for the conduit. This way the box is not in direct contact with the wall and 1x furring strips can be used.

Thanks.

OK, I starting ripping out the old basement this weekend and the walls are not flat, so I will be framing a 2x4 wall over the 2" xps.

My next job is insulating the rim joist area. I was considering using eps in the rim joists. Does this sound ok? It is left over from the old basment so I figured I could save some money and re-use it. It is in perfect condition. So I have a few questions about caulking.

What type of caulk should I use with the eps?

What type of caulk should I use with the xps?

And lastly, what should I use to seal the sill plate at the foundation, foam or caulk?

Thanks.

Those foam cans are a mess.
I'm trying to use them as little as possible.
I've been schmeering latex (dap230 or something) caulk in the rim joist area with xeps.
I say 'schmeer' 'cause you can't get you get the caulk gun on the bottom joint.
I've been putting in several (4) blocks of 2" xps in each bay and caulking between each. I'm gonna link up with the wall foam for a continuous layer - that's the plan anyways. You go through a lot of caulk, plus it's taking forever. I'm committed now though and stubborn.
You're supposed to use non-petroleum based products with the foam, but I found the polyurethane foam was real stiff, and with all the schmeering with the fingers, the latex is probably better for the skin too as well as fumes and cost.
I don't know if the latex has petroleum, but it doesn't appear to be melting the foam.
My plan is to leave the foaming til last, since you have to use the whole can at once.

I used slotted 2" xps nailed on with 3" ramset nail tru a 2.5" roofing washer taped the vertical seams using house wrap tape and used low expansion foam to seal floor, 2 x 4 wall apx 2" air space from xps with fiberglass insulation (R13) then 2 x 2 dri core panels on floor, 8" total from foundation to sheetrock, town inspected no problems. 4" thick Mineral wool firestop @ top plate airspace!!

why not fame right up against the xps?

An airspace provides a thermal break between the xps and lumber.

The foam board (EPS,XPS or isocyanurate) is the thermal break.

That's why the Wallmate and equivalent systems are designed the way they are. The same with Superior Walls, where the studs are cast in place directly against the XPS and in the Building Science Corp. recommended systems (See Link below).

Here is a link that might be useful: Basement Insulation Systems

BTW, testing shows that mineral wool is not effective as an air barrier compared to alternatives. (See Results of various assemblies in the link below.)

Here is a link that might be useful: Air Barrier Connection Techniques

Scrap all that. Build a regular 2x4 wall an inch from the foundation and then spray closed-cell foam 2" thick and the rim joist. You can leave the bays open and have room for your outlets/etc. and then put your drywall on. Done.

Absolutely!

But be prepared for sticker shock.

Also, Zones 4-8 where governed by IECC 2015 will need a higher R-Value than provided by 2 in. of ccspf.

Worthy, do you have an updated link for the air barrier data? I’m interested in reading it!

The constant problem with internet footnotes!

This seems to be the original link with a new address.See "Conclusions"

....

"Given their high permeability, open cell gaskets, mineral wool and
perforated polyethylene air barrier joints should not be used as air
barriers."