I am wondering if anyone has any opinions about insulating under the floor above an unheated basement. I have already insulated the sill space on top of the foundation walls between the floor joists, and maybe that helped but the floors still seem to be very cold. I have an oil-fired boiler in the basement which in theory should keep the basement no less then 60 degrees just from heat loss from the boiler, but it seems like it gets a lot colder than that down there, especially this winter (New England). Also, I plan to finish the basement someday, and part of that plan, I assume would be to provide heat to the basement. Will this necessitate ripping out the floor insulation or will it not hurt anything to keep it at that point? Thanks for any responses.