Once we get rid of all the mold, what's the best way to moisture-proof our crawlspace?
So we escaped hurricane Irene and made it to Disney World
just fine! Hurrah! But that meant we weren't home during Irene, and didn't know whether the crawlspace under our house flooded or not. And there was a decidedly musty aroma in the house when we got back from vacation... suspicious.
Soooo we went to take a look at the crawlspace under our house, and found that the insulation under the floor was visibly water-damaged, with the vapor barrier hanging down in places. We don't know if it was from the hurricane or not, but we suspect it's actually been falling apart for some time and we never thought to look before. So I used ServiceMagic to get quotes from three mold remediation dudes.
Mold Remediation Guy #1 wants to remove the old insulation, put down a mold bio-cide, apply a foundation sealant and anti-microbial encapsulation, and then put in R-19 insulation.
Mold Remediation guy #2 wants to remove the old insulation, sand the joists and subfloor, fog the area with a mold-killing chemical, put in R-30 insulation, and install a dehumidifier.
Mold Remediation Guy #3 has not yet given us a quote, but he did find a hive of bumble bees down there, which we had removed yesterday. >_<
Both #1 and #2 said the old insulation was done wrong -- #1 says it was the wrong kind, and #2 said it was put in backwards with the foil facing up and not down. They seem to agree the vapor barrier shouldn't have been between the insulation and the air of the crawlspace, but should instead have been between the subfloor and the insulation. Sigh. Before we had it put in about eight years ago, there was no insulation under there at all.
More information that might be helpful: The crawlspace is external access, about three feet high, apparently home to millions of giant crickets. It has no windows and is not ventilated. This is on Long Island, New York, so quite humid and a lot of variance in temperature.
To get into the crawlspace, you go down a few cement steps to a little wooden door in the side of the house. There is a drain at the bottom of the steps, but I'm not sure if it's working, and I suspect that if the steps aren't covered, water would enter the crawlspace when it rains. The steps have until the last week or so been covered by a ramshackle contraption built by the previous owner consisting of plywood covered by astroturf, but this is now rotting to pieces.
tl;dr: I have no idea how to pick between the foundation seal and the dehumidifier. Which is better to keep moisture out of the crawlspace under my house? Or is there some other thing I should be doing and they're both wrong?
Bonus questions: Should we replace the crawlspace door with something more air or water-tight? Do people traditionally cover the steps down to an external crawlspace, and if so, with what? How do we find out if that drain is still functional, and what do we do if it isn't? In general, is there anything I need to know about keeping this awful space under the house dry?!