I purchased a house about 4 years ago and a year ago I started noticing that my floors were uneven as you walked from one side of the house to the other...it reminded me of a wave, a little down, then back up, then down again. My flooring is a combination of carpet and wood flooring and the wave is more apparent on the carpet. I had a company come out and they went into the crawl space and installed some beams to support the floor in these places, but 1 year later the flooring is wavy in another area. My house has a vented crawl space of about 24 inches with no insulation. It is 43 year old home in South Carolina close to the beach so there is a lot of humidity and there is moisture in the beams and some dry rot. I have had 1 company recommend that I have a crawl space vapor barrier installed along with sealed vents and a dehumidifier for a cost of $20,000. Then another company suggests having the underside of the house spray foamed with a closed sell insulation foam for about $8500. I would appreciate any advice on this problem as I do not know what to do and I would like to sell the house, but need to fix this problem first. Thanks!