WOW !!! Sounds like an industrious a project (the kind I like).
This completely changes my viewpoint, but before I offer any other suggestions, let me make sure I understand exactly what is going on:
You have a 23-year-old modular home, a ranch (1 story) measuring 40X24 feet. It is a modular, and not a mobile home, right? (Mobile homes have wheels attached, modular homes, sometimes called prefabs, come semi-assembled, then the pieces are bolted together at the site). If itís 40X24, then it was two 40X12 pieces brought by trailer to your site, then bolted together.
Okay, so you have this 1 story house, and, besides the repairs, you want to essentially lift it off its foundation, then upgrade the foundation, build a NEW first floor, then take the original house and put it on top of the newly constructed first floor, creating a 2-story, with the second story the original part of the house. In other words, when you are all done, you will have a 2-story home, with the original ranch home up on the second, and a new first floor. Do I have the story right?
Iím assuming you have weighed the cost of doing all this against just demolishing it all and building from scratch. You know, you will have to hire a crane to lift the existing modular at least 15 feet high, and you may even need to take the 2 halves apart and lift each one separately. Separating the halves means finding the bolt-seams in the walls, removing the drywall, then disconnecting the plumbing and electrical, unboltingÖhave you investigated all that? I could see that as being potentially expensive.
If thatís the case, then we need to throw out our previous discussions and revisit everything. You are essentially building a new house from the foundation through first floor, which means we can approach this from a new construction viewpoint. The suggestions I gave before were more towards existing home problems. I believe I can offer a more economical solution than the one you are planning, but Iíll wait to see if I understand your plans correctly. This is much more than just a crawlspace wetness issue. WOW!