Here is my situation. I have a log cabin in the mountains of CO that is built on pier and beam and 32" concrete stem walls, 2X10 floor joists on 16" centers. The only insulation in the crawl space is 3/4" extruded foam on the interior concrete of the stem walls. The area is dry in the winter and by late summer it gets a little damp with the wall vents open. The floors are very cold in the winter. I just installed a Homestead soapstone heater and it heats the 1100 sq ft area with cathedral ceilings pretty well, but know it would do better if I made some improvements in the crawl space. I have been reading a LOT about the proper way to encapsulate a crawlspace and seem to get a variety of opinions. I would like to be able to not have to drain the water lines every time I leave in the winter. I am in the process of installing extruded foam board in the floor joist rim area and foaming around that to get a seal hoping that will improve the heat loss. I am also kicking around the idea on putting down a vapor barrier on the dirt floor and attaching that to the existing foam board on the concrete exterior walls. Here are some questions that I need answered. 1) can you get the liner to stay attached to the existing foam board on the walls and get a good seal? 2) since I don't have forced air or any air movement in the crawl space (I plan to completely close off the vents) should I consider a de-humidifier? I don't think they work very well when it is above 45F but know absolutely nothing about dehumidifiers. 3) am I kidding myself to think once I get everything done that I have listed above that I can keep from draining the water pipes when I leave for a few weeks even if I have a couple of light bulbs on in the crawl space? I would not leave the well pump on either. I would like to leave a small heater on just to keep part of the house around 45-50F. It does get pretty cold at the 9200' elevation. I plan to eventually retire there and want to get it right. Any help would be very much appreciated.