Dirt floor conditioned crawlspace with horizontal 80% furnace, and mold remediation
I guess the title is a mouthful - I have discussed my house a couple times, but in short here's the synopsis of the relevant bits:
- built 1917 in SE Michigan, the house is on a dirt crawlspace with no formal foundation.
- the house is heated by a 80% efficient furnace which is located in the crawlspace.
- the crawlspace exterior is enclosed by rotted wood planks with stone fascia over it.
- I have been adding footings, posts and beams to provide support with the goal of replacing the stacks of cement blocks sitting directly on dirt.
- I have added a sump pit and pump at a low spot, this has eliminated flooding.
- I run a dehumidifier.
- There are 2 vents in the crawlspace, and it is conditioned.
My intent is to install plastic sheeting on the floor. Mold is visible on the dirt, a black light inspection shows specks of probable comtaminates on the 2 original footers under the only original structural beam in the crawlspace and on those cement blocks. Mold is visible to the naked eye on dirt under the furnace.
A suggestion that seems to have merit is venting the crawlspace to outside, creating negative pressure in the crawlspace to prevent mold intrusion into the living space. I'm wondering if the presence of the furnace makes this a problem, but I would rationalize perhaps not if it just means CO2 pulls into the crawlspace and out through the forced air.
I'm also planning to enclose the furnace and duct outside air directly to the enclosure, which maybe resolves the issue above, but then there's the question of what order do I need to do things - in particular, would I need to lay plastic under the furnace before building the enclosure, then hold off on the rest of the plastic for the crawlspace until after the ventilation is in operation and I dig out suspected contaminated dirt?
Please do NOT consider any "before" picture of my house as any kind of endorsement of any particular construction method. In fact, you should probably assume that if I post a "before" picture, I am posting it because I am soliciting advice on a proper replacement for one of MANY things done wrong by a previous owner.