moisture in crawl space - navigating my options
I have a home built in (very humid!) Atlanta in 1950, and expanded in 1970, so it's on two dirt crawl spaces. We're having issues with moisture in one specific area of the newer crawl that shows up after heavy rains - we notice because of a strong muddy smell (and sometimes a mildew-y smell follows that). We've gone under to look when the smell is there, and there is moisture that seems to be coming through the brick. We've never seen puddles of standing water, but there is mud splashed on the walls, so that suggests we may have had some puddles in the past. The ground on the outside of the house in that area is shady, and tends to hold moisture (there is moss growing there) but it slopes away from the house. We have gutters that we haven't always done a great job of keeping clear.
The older crawl does not have a vapor barrier at all, and is powder dry. The newer crawl has a 6 mil vapor barrier, but it doesn't cover all of the ground. There are vents for both crawls that are just open year round, covered with mesh - I don't think they can be closed. We have a new, expensive HVAC unit installed in the older crawl. There's no insulation under our house at all (sometimes I can see sunlight through the floorboards near the vents!), but I think that's a whole 'nother issue.
We've had 6 different companies come out to look, and each has a very different answer for us, at very different price points. I think we've got a consensus that this isn't a major foundation issue, and that while there is some mold and mildew in the crawl, that it's minor and isn't going to require any real remediation effort.
The options that are seeming the most sensible (er, cheapest) to us are to either:
option from contractor 1 - install a french drain to lead water away from the problem area, and then install a 6 mil vapor barrier in on the ground only in the crawl, and leave the brick uncovered. (cheapest quote)
option from contractor 2 - lay a thicker (12 mil) vapor barrier on the ground in the crawl, and run a thinner (10mil) vapor barrier up the brick, so that the entire crawl is covered up to the wood beams. (second cheapest quote)
But we've also had a contractor tell us we don't have a problem at all, one suggest we need a dehumidifier / air exchange system installed, one suggest we need total crawl space encapsulation, and one suggest we need $20k of foundation repair. No one seems to be on the same page about what to do! And I'm out of contractor referrals, and the internet is failing me.
Anyone dealt with this kind of thing, or know anything about it, or know where I could turn for advice?