Thanks so much for the tips
I think I've been dissuaded about the straw bales idea... I didn't even think about the flammability factor... I was just thinking it would really attract mice n such and I figured our kitties would take care of that problem.I think the styrofoam insulation sheets sound like a much easier/practical idea and plus we will be using heat tape as well. Doubling up on the insulation on the northside sounds like a good idea too. Anyone have a general idea how much that styrofoam sheeting costs? We are on a tight budget (as most homesteaders are) Maybe it wouldn't hurt to do the pumpkin leaf bag thing as well haha... I can see it now
Around here, the 2 inch thick "pink" or "blue" insulation board costs $1 per sqft.
I would use the pink or blue stuff (this is extruded polystyrene) rather than the white stuff, which is a little cheaper, but won't hold up to the weater as well. With the pink or blue you could actually bury the bottom of the insulation board a few inches into the dirt, so you get a good wind seal on the bottom. Ideally, it would be good to have the area under the home sealed up so that cold air cannot infiltrate past the foam board. It would be good to put poly film down on the ground under the whole mobile home to keep moisture from the soil from causing problems in the unvented space.
If you want to get an idea how fast you might pay back the cost of the materials in heating bill savings, you can get a rough idea from this calculator:
For example, assuming a 1000 sqft home, in a 5000 deg-day climate, with a current floor R value of 4 and a total R value of 15 after the foamboard is installed, I get a fuel saving of $410 in for natural gas at $1.50 per therm, or $600 for propane at $2 per gallon -- pretty good
You can plug in your actual home size and location to get a better number.