Great comments everyone...price ...can be between $2- $3/sf. Anything more is overkill. As to the smell of some companies poly ... there was a run 4+ years ago where a handful of manufacturers that made a poly that was white on one side and black on the other and was reinforced. 1 of 10 after several months to a year started smelling like cat pee and got stronger. I ripped out a handful of these crawl poly's. I wouldn't blame the sealed company's only because we all look for a deal on plastic to pass on to you ... and the odor doesn't start for awhile...that could be 400 crawls in 6 months for a handful of us. That's 40 of them stinking and 30 notice enough. About the DIY'ers ... I have DIY hardwood floors ... brakes... toilets...etc ... It takes me 6 months to get a diligent guy up and going on crawls where I can let him run and inspect his work after. I couldn't imagine the $ lessons learned that a DIY'er gets into. Just know it takes one really experienced crawl space tech and 3 new techs to finish correctly a 2600 sf sealed crawl using 50 labor hours. Know that 50% of your homes air comes from the crawl space so a poorly prepped sealed crawl can trap some pretty nasty mold. Dehu's: to use or not to use??? Tests show that mold has not grown in sealed crawls that use a 4 inch air supply line per 1500sf with average height of 2.5 ft. Though the humidity reduces down in the South (Raleigh Area) to 68%-77% when sealed still leaves high humidity compared to the average homes humidity of 52%. But mold does not grow. Why? I can only guess ... A. Ground, where mold comes from, is sealed off B. Air is slightly circulating from the air supply line on your supply side. And a dehu wholesales $1000 average ... then install and electrical hardwire hookup and gravity fed condensation line. $1600-$1800 should be fair?? And that will take your humidity down to your chosen level ... most, I have found, chose 50%. Now here's the rub ... your dehu is taking up a chunk if not all of your energy efficiency that your conditioned sealed crawl gives to your AC system. So if you don't take the old insulation out and seal in the mold and the defication from the crickets, mice and snakes and you aren't getting any efficiency out of the sealed crawl ... then why invest $ at all??? No savings or better air quality. My recco: pull floor insulation, sanitize entire crawl for SUPERIOR lifetime air quality ... seal crawl and forget the dehu and gain 15.8% energy efficiency on new homes past 2008 ... higher efficiency for older homes. My pet peeve.... if a home has mold on the beams and evidence of cricket poop ... little black pellets all over the joists ... I wont seal it without pulling the insulation and disinfecting the crawl. But 95% of all companies seal the crawl trapping in ALL THAT MESS and that's there standard seal crawl practice. That should be criminal!!! Like all the contractors who knew back in early 1900's that lead based paint was killing children but kept using it because it was cheap ... until 1970's when a law was passed after ??? more than a million baby's past away. I feel mold in the crawl is that same issue that is slow to REAR ITS UGLY HEAD ... buyer beware ... short cuts can hurt you long term. www.SealedSolution.com

This tends to make homes less than desirable when you sell. The garage is unconditioned area of home and aren't included in the heat load calculation when the home is built and people often under estimate the amount of money required to do this right, to be able to make a garage comfort enough to be livable in. If you convert it and the room is uncomfortable you won't want to live out there. Then you find out how much more it will cost to make the room comfortable. It's a double edge sword. You need to think long and hard about this decision and find out true costs to do this the right way. Many times people think they can steal air (heating or cooling) from the HVAC system of the home, just run a duct over. But this doesn't equate to 'comfort'... Under extreme heat or cooling the system will likely not perform well enough and in the process makes the rest of the house uncomfortable to boot. If your house is too small, it is almost always the better way to add to the house. If you can't do that it might be better to consider buying a larger home and selling this one.

^In both plans immedialy above, you could change the swing on the front door so you have a better view at the entry. You could also put up a small wall, half or full, to get that foyer entry. Something interesting.

There are plenty of homes in plenty of places where under the living space floor is air of outdoor temperature. The key is to make sure between the garage ceiling and living space above is well sealed from an air infiltration standpoint (you need that for safety because it's a garage anyway) and adequately insulated. Spray foam of the right kind properly applied to the necessary thickness will do that. For illustration, the attics of houses, maybe yours too, is outdoor temperature in winter. It's not a problem if the air sealing and insulation are properly done. There's no need to heat the garage. An HVAC contractor will give you equipment choices but your builder needs to be on board to properly seal and insulate the space.