Hygro thermal Regions of North AmericaSource: Building Science Corp.

In most of the rest of the country--cold and very cold--at least one-inch extruded (XPS)would be satisfactory, followed by fibrous insulation. The vapour barrier is not necessary, but according to Building Science won't be detrimental if building inspectors insist on it.

What do you think of that configuration?

2 Questions to confirm my process:
1) When I frame the wall in front of the XPS, do I frame right against the XPS or leave a gap (I'll be adding batt insulation in between the studs).
2) Since I'm using the 1" to 1 1/2" XPS, I'm debating whether or not to put vapour barrier between the studs and the drywall. The vapour barrier is relatively inexpensive and fairly easy to install with 2 people... is there any benefit to it aside from the inspectors preference?

Thanks

Fine.

Place the framing against the extruded polyurethane boards (XPS). A vapour barrier is absolutely not needed. If there's still some inspector somewhere who is asking for it, you can always (politely) show them the Building Science Corp. publications.

The leakiest parts of the basement are the abovegrade spaces between the joists and the intersection of the rim (mud sill) and the concrete. You can foam all the space with do-it-yourself polyurethane spray or use XPS between the joists and caulking and small cans of polyurethane spray (Great Stuff etc.) for all the other gaps.