Anyone an expert on crawlspaces?

[pscot]

3. Two things

You have to allow air to circulate or moisture will get up into the house.

You need a vapor barrier between the ground and your floor. Jacketed insulation stapled between the joists is fine. Face the foil or paper side down. The insulation comes in 6 foot batts, either 18 or 24 inches wide, depending on the joist spacing. Screen all vents. Critters love the fiberglass; it makes nice warm nests where they make lots more critters. They'll make a shambles of your expensive insulation. It's possible to do it yourself if you're reasonably handy. You can get spring thingies that bend up between the joists and hold the stuff in place. It's not a pleasant job. Good luck.