When we bought this house we had radon testing done. Radon tends to concentrate under slabs so we weren’t surprised when it came in high under the guest house. The sellers put in a radon remediation system in for that part of the house. The installers drill a hole thru the slab and install a 4″ PVC pipe which runs outside the house and then above the roof line. Right as the pipe exits the house there is a blower which runs 24×7 and sucks air from underneath the slab and vents it above the roof line.
While it wasn’t too high under the main house it also wasn’t zero. We knew we were going to seal the crawlspace, which would eliminate the foundation vents so we figured that we might as well put in a second radon system. Since the main house is built above a crawlspace the installation is a little different. Because there is no slab, the installers lay down drain tile followed by heavy plastic. This isolates the dirt from the rest of the house. The radon blower is hooked up to the drain tile and vents above the roof line. The installers ordinarily use 6 mil plastic, but I ordered some heavy duty 16 mil vapor barrier. It’s seriously tough stuff and will wear a lot better than regular plastic sheeting. I knew I was going to be under the house quite a bit working on various projects and didn’t want to be poking holes in the plastic. I don’t have any before pictures of the crawlspace, but it was pretty gross. Smelly, musty, dirt. Lot’s of insulation had fallen and there was plenty of evidence of small animals making their homes there.
It’s not a glamorous project, but it serves a purpose. We’re glad we had it done as it has reduced the moisture under our house. There is evidence of mold on some of the floor joists, but now that the moisture is gone, it’s not spreading. Once I get the floors all buttoned up, I’m going to rent a fogger and fog for mold. For the work I’ve been doing, I’ve used a bleach solution to wipe down affected areas before covering them up. For example, when I reinforced the floor joists in areas, I’d wipe down both sides before sistering a joist to it. This way I wasn’t covering up mold spoors and inviting a problem later on. My sister gave me a natural mold killer based on oregano oil. I’ve tried it in a few spots and I’m curious to see how it performs because it sure smells better than bleach.