Nice article worthy, thanks for that... I love this part... "DonâÂÂt vent dryers or other appliances into the crawl" Who would do that? Every load of washing machine water direct into your crawlspace. Sheesh. For closed conditioned crawl spaces the recommendations were... â¢Insulate the perimeter walls to the level suggested for above-grade walls in your climate. â¢Exterior perimeter wall insulation is a good option to consider, especially in new construction. It eliminates the problems of moisture management associated with interior wall insulation and provides the possible benefits of additional thermal mass within the structure. The downside is you have to protect the insulation from termites and the above- grade portion of the insulation from deterioration caused by weather exposure. â¢When insulating a crawl from the interior, you should protect rim joists from condensation with foam insulation. â¢Use water-resistant insulating materials, such as rigid-foam board or spray foam properly protected to meet fire ratings. Avoid using air-permeable insulation, such as fiberglass batts or spray-on cellulose. â¢Power venting a sealed crawl space to the exterior can reduce the movement of air from the crawl space into the house. This can improve IAQ, but at the added cost of operating and maintaining the exhaust fan. I just might do that. i.e. insulate the walls and rim joists cuz our floors over the crawl space zone of the house are really cold in the winter. The issue there is "properly protected". Per the fire ratings, XPS sheets are to be covered w drywall or finished. Obviously a crawlspace you're not going to finish in drywall like you would a full height basement. So they don't really address what to do there -- cant leave it exposed but you're not gonna frame and finish... Thoughts?

I live a few miles west of Indianapolis, same climate as you. Here is what we do. lay 6 mil plastic on the ground overlap 12" and run it up the wall 12". Insulate between the floor joist from the box sill out 2' what ever the thickness of the floor joist. (do not insulate all of the floor). Staple r-16 to the plate and let in droop 6" onto the floor. Close and seal all crawl vents. We also condition the space by installing 2 vents into the existing duct. This will prevent condensation and keep the space dry. You may think that you're wasting heat but you're heating the floors and there will be a noticeable difference. We have been doing this for 30 years and it does work very good.

Haha I think the OP meant 'attic'. Took me a minute to interpret the title too. Vapor barrier is there to prevent warm moist air from a heated space from infiltrating the insulation and condensing as it reaches the cold side, which can cause mold and rot. If the attic is unheated (no heating outlets) it probably doesn't matter, which is why you're getting some "no" answers. Sounds like you put a dividing wall to block off the outer part of the attic to create that 'crawlspace' (which I thought were only UNDER a house but what do I know) and that wall has insulation and vapor barrier. Even if the main space is heated, as long as the dividing wall has a vapor barrier and the crawlspace is unheated, I would think you don't need vapor barrier in the crawlspace. But I'm an amateur just going on basic principles.

South Carolina