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

can lights are recessed lights if Insulation Contact IC they have holes in the housing. you will be able to see light thru the holes when in the attic. retrofit by boxing in with ice chest with 4" clearance on top and sides, cutting ice chest to fit tightly to attic floor and caulking in place. or buy air tight inserts to retrofit from inside the house. hvac boots are the supply box that attaches to attic floor and supply grill on inside of house. I use mastic tape remove the supply grill from inside the house and seal sheetrock to inside of supply box (hvac boot) at the same time mastic seal plenums (supply and return) to equipment, and mastic seal ducts where they take off from supply plenum. I use hardcast brand mastic tape and paint on mastic that is applied with a brush. electrical & plumbing penetrations are also sealed prior to insulation install. if you insulate without doing any of this you will still see a savings, but to do these things before insulating you will improve the indoor air quality of the house (esp if using cellulose) the average house has 30% duct/return leakage. in our hot humid climate these leakage areas introduct humidity laden air into the house. hvac has to work harder to remove humidity. while I understand the frustration of adding to the list when wanting to simply blow insulation and be done with it..these areas make a huge difference in how the house performs. insulation is essentially useless when air moves through it. to complete the air barrier, and minimize duct/return leakage is the right thing to do. also be aware that cellulose creates a fine 'dust' (actually borate treated newspaper) that enters through small cracks in attic floor into house. we can help advise your diy if you'd like. best of luck.

We are climate zone 5 & 4 (green) - thanks for the link! We do plan to use the rigid foam, seal around it, and then use mineral wool bats between the studs and as extra insulation in the rim joists (which will also have sealed rigid foam). I think this will bring us up to code. I would prefer not to use the spray foam. Our daughter is more chemically sensitive than the rest of us and I am concerned she will react to 3 giant walls full of spray foam. Looks like we will be ripping out the studs! Ugh! Thank you so much for the advice!

You need to fir out the interior and create a stud wall around the entire perimeter. You also need insulation below the floor, and at the ceiling line. The stud wall will give you room to run the required electrical and attach drywall. You will also need to update your windows in any bedroom to those that permit emergency escape. You also need a plan for the rough plumbing creation, which in your location will easily freeze. Which is why many homes have basements. And all of that presumes that the building has an approved foundation type for a residence, and the local municipality will permit its reassignment from agricultural to residential. The typical pole barn foundation into dirt is not approved for a residence. A pier and beam foundation would, if the piers are concrete and below the frost line. But that causes many more issues with the needed insulation and plumbing in your location. It's unlikely that the building could be as cheaply converted to a residential classification as a new build designed to fulfill those requirements be built correctly from the beginning. Retrofitting is always much more expensive. Especially without a proper foundation.