I have a house that was built in the 50’s. It is pier and post construction (the house has about a 3 foot crawl space underneath). We noticed in January that the floors, even with carpet, were always cold and often felt damp. ( not actually wet, just from the cold) A friend of ours told us to just buy some insulation, and staple it up there. I was looking online and it said Vapor barrier was needed against the warm side, before the insulation. How do I go about doing this? Do I need to put a vapor barrier on the ground as well?
What is truly needed? What r-rating should I use? DO I just hammer staple the insulation in?

Oh I live in Southern California about 6 miles from the beach. So the temperatures are not extreme cold. But we get alot of moisture, and fog. I have a 2 year old and a one month old so we want the floors to not be a heat suck.

Check with the local inspection dept.; if you meet the local codes, you should be great! here in the south, vapor barriers are being installed in crawl spaces on the floor and against the floor. if you put up the insulation with the vapor barrier attached and the vapor barrier at the top, you would use steel wires to support the insulation, available where you buy the insulation.if you put the vapor barrier down, you can staple it to the bottom of the joists.

Batt insulation is available as “faced” (paper and foil), unfaced or encapsulated. The paper is the vapor barrier and it is installed to the “conditioned” area.So the paper side would be placed against the floor.. Encapsulated is an unfaced batt encapsulated in a plastic bag. Here on the truely left coast, there are several temperature zones, which determine the required insulation values. However, until you travel north of San Francisco, the normal value, in today’s world, for new construction, is R-19. The wire stays are in the shape of an elongated “U”, sharpened on the ends for easy hammer placement, at 16 to 24″ OC. If this a “honey-do” a good pair of coveralls, gloves, dust masks and knit cap are in order. Check with insulation contractors in your area as another source for the materials. Measure the sq.ft. of your floor area and reduce by 10%. Where you have a foundation vent, hold the insulation back 12″ from the the vent screen.