My newly-purchased 1950s home has a below-grade crawlspace with a poorly-poured concrete floor. Specifically, it is very coarse and looks like it was poured and spread with a garden rake. In some places, there are large holes that seem to go down to the dirt. Not good. Also on the list of "not good": we have slightly elevated levels of radon in the home.
Ultimately, we want to use the crawlspace as a clean, dry, conditioned space that is an extension of the basement used for storage.
My plan is to remove the door that separates the crawlspace from the basement, then have my HVAC guy run a supply line or two to the crawl. The supplies supply conditioned air, and the open entry to the crawl will serve as a return. I am also going to seal the outside walls of the space with insulation - but I will save the insulation details for another post.
In order to make the space clean and usable for storage, I obtained a quote for a poured concrete floor. The contractor's intent is to pour a couple of inches of concrete right over the existing "concrete" floor without chipping the old floor out, and then trowel/level it nicely.
My questions are:
Any concerns with pouring concrete right over the existing "concrete" floor?
Assuming that I am OK to proceed with pouring over the existing floor, do I need to stipulate that the contractor lay down a continuous sheet of polyethylene as a vapor barrier? To be clear, if I have the contractor do this, this poly sheet will sit between the old "concrete" and the newly-poured floor. Or is the vapor barrier a lost-cause (or, worse, going to cause a problem) if I do not remove the old floor?
I haven't lived in the house very long, but it looks dry (contractors have agreed). Also, for the record, I do have some water supplies and drains that run through the crawl to the upper floor. That said, how important would it be to install a floor drain? If I were to have a plumber install a drain, would this drain flow into the sewer? To do this, I think that I would have to have the plumber bore a hole through the foundation wall, which sounds like a huge job. So unless it's highly recommended or a code issue, I would rather skip it.
Regarding the radon, I am going to have the concrete contractor install a vent pipe into the floor (both the new floor and even down through the old floor) for sub-slab suction. My radon mitigation contractor will connect this vent pipe to the radon mitigation system.
I would love to hear any comments from the experts. Thanks in advance!