Sounds right to me. With two inches of XPS on the wall, a vapour barrier (Kraft paper) is no danger, according to Building Science Corp. (The XPS slows the vapour drive in both directions.) I've been required by Code to use a polyethylene vapour barrier over XPS and fg and still have not experienced moisture or mould problems. This post was edited by worthy on Mon, Jan 6, 14 at 18:03

"First, unless your local authority requires it, I know of no code requiring insulation for basement ceiling joists (or 1st floor joists). I live in an area of winter lows between -20 & -30 and there was no such requirement at a 2008 completion date; and NY bases their code on the IRC. " Chapter 11 of the IRC from the 2000 through 2009 versions all have required basements to be insulated....even in New York state for 2008 builds. See the link below. The International Energy Conservation Code (adopted in most US states) also requires it. ------------ Basements is nearly all US locations are required to be insulated either in the ceiling or foundation walls. How much insulation is determined by where you live, what type insulation you will use, where the insulation will be located, whether or not your basement walls are considered below grade or above grade, and from what materials the basement walls will be constructed. For most locations, newly constructed basements either need to be insulated in the ceiling of the basement using a minimum of R-30 or on walls using R-13 cavity insulation (batt) or R-10 of continuous (rigid foam). As mentioned, the best insulation is rigid foam located on the outside of the foundation. But rigid foam cannot be used in regions of high termite infestation and must be parged with mortar when installed on the outside above grade. Rigid foam used on the interior of the basement walls can also work, but as mentioned, it must be thermally isolated from the habitable space to prevent ignition in a fire. This can be done by framing walls in front of foam applied to the masonry foundation...then installing wallboard to themally isolate it...or by installing faom insulation like Thermax which has a foil coating which can be considered a thermal barrier. Bottom line is that insulation for Virginia and most places in the US is mandatory in new home construction. The only question is where the insulation and how much is required to be installed. Here is a link that might be useful: New York State Building Code

Hi illinigirl, The standard insulation used under basement floors is rigid insulation (XPS -- extruded polystrene). It comes in 2 inch thick often blue pieces of styrofoam. Dow manufacturers it among others. It is not spray foam. We used it in our build -- we are in southern Canada. The labour to lay the rigid insulation sheets was not high. The guys had to dig away a bit more gravel so the basement ceiling level was not compromised. They used the red tuck tape to attach the sheets to each other. This allowed the concrete flat workers to pour the floor with wheel barrow loads. I am not sure yet what a difference it will make as we are partway through our build. We have hydronic in-floor heat that was just turned on for the basement level. The floor is wonderfully warm (mostly due to the in-floor coils). We were required by code to place the rigid insulation because of our planned in-floor heat. Otherwise, I understand, the heat from the coils would not just heat upwards and instead would have been wasted heating underground? We did place the rigid insulation around the perimeter of our our unheated garage. I will go and step on the parts of the garage floor that have the insulation vs the parts that don't to see if I can detect a big difference and report back. Our architect spec'd for this rigid insulation under the basement slab. At the time, we had not planned for the in-floor heat. In other words, he felt it was a good practice even without in floor. The rigid insulation sheets are not cheap. We paid $25.00 a sheet (each one is 2 feet by 8 feet). We are in Canada where everything seems pricier. You can calculate the area needing coverage and see how much your builder is charging for labour vs material to help you decide if the price is reasonable. Don't forget the tack tape is also not cheap. Best of luck. Carol

Air space between the insulated wall and the foundation wall invites condensation and should be avoided. Your interior weeping tile system is not all that unusual. However, it poses a problem of how to install water impervious insulation. Normally, you would simply attach rigid foamboard such XPS (extruded polystyrene) with concrete fasteners, then frame over that. But it looks like the membrane on your wall was painted over; penetrate it with fasteners and you'll be reducing its efficiency. You could experiment with foamboard adhesive. Spraying the existing wall with ccspf is an alternative. But it's expensive and you'll be out of the house for a day due to fumes. No need to notch the 2x4s if you put 1.5"-2" thick foamboard on the walls. When I finish basements, I always put 1'' thick strips of XPS under the bottom plate to reduce the chance of rot from minor leaks and the upward drive of moisture through the floor. As for the septic pipes, cut the insulation as close as you can, then use handheld expanding polyurethane foam sealants, such as Great Stuff, to fill the gaps.