My situation is tricky. I have a standing crawl space underneath my kitchen. It has a dirt floor, stone walls, a small basement window, sump pump and an access door. Oil tank is located against the inside stone wall. I can also get into this space through a door in my basement. The house was built in the 1920's. We've been in the house for 4 years and previous owned did put batt insulation in the floor joists but that's about it. Since we moved in, I did the following:
Replaced the old wood window with a replacement
Used foam where I felt obvious drafts
6mill on the dirt floor taped seams
Added more insulation (unfaced) in joists that were not covered
Added some insulation on the walls attaching them from the top
My kitchen floor above the space is vinyl and still pretty cold although the crawl space feels ok temp wise. It stays pretty dry for the most part. One thing I've noticed, after pulling up the plastic a little to check the ground, is a good deal of moisture under the plastic. I'm assuming that the plastic is doing the job. However, after pulling it back, there were a few salamanders underneath. Made me think twice about using the plastic on dirt. Building Science didn't say anything about using plastic on the dirt floor.
Basically, I'm planning on using unfaced batt under the floor instead of the faced, leaving a small space between the sub floor and insulation. Next, as suggested in the bulidng science article above (figure 7), use foil faced isocyanurate rigid foam over the insulation and actual joists. Not sure what to do regarding the 6 mill plastic over the dirt. I don't want salamanders making their way into my house. I'm looking for some advice on this from poeple that know more about it. Does this sound like a good plan or would you suggest a different approach? Thanks.