When we hire contractors to remover drywall down to the studs on an outer wall of our house, it is not uncommon to find what I assume is Bermuda grass growing inside the wall, 3 - 4 feet long tendrils among the studs behind the dry wall. Dead looking yellow tendrils. It is a slab foundation house, about 60 years old. The current contractor seemed very concerned when he found a lot of the grass tendrils? Others have not been concerned. We have mulch between the grass and the house, and a small plastic boarder around the grass. The grass is a mixture of (I forget what) but not Bermuda...but of course I sometimes lose the battle of keeping Bermuda grass out of the lawn. Is this a problem?

Hi. I own a 1970's brick ranch in SC, on a crawl space. When I bought the house, the crawl was a swamp. One of my first tasks, installing proper drainage, piping everything well away from the house. As expected, the crawl space was bone dry from that point on, however, the duct work and insulation in the crawl were ruined. After replacing the HVAC , duct work, and insulation, I decided to do a 'semi' encapsulation. I put down a good (not perfect, but good) vapor barrier, closed off all of the vents, and installed a good dehumidifier. I've since been pleased with the results. The crawl is clean, and bone dry...a pleasure to work in, when i have to. Last spring, I happened to see that my county is 'zone 1' for radon. I bought a detector, in May, and my radon levels were below 1 most of the summer. Unfortunately, once the attic fan quit running regularly, my radon levels started creeping up. Since the AC is not running, i'm ventilating the crawl for about 7 hours a day...this helps, but my readings are frequently above 3 pCi/L, and can shoot up to 7 after a good rain. I want to do whatever I can to protect my family, however, I can't afford the $15,000 or so a mitigation company would charge to fully encapsulate the crawl and install mitigation. I'm capable of correctly installing the plumbing and mitigation fan, but i'm not sure that my vapor barrier is air tight enough to allow the mitigation fan to work as intended. I have a total of 52 cinder block piers in the crawl, and the ones on the outside walls, are 2 to 3 inches off the brick veneer. Getting a good seal against the veneer wall will be nearly impossible (see attached photo). Would sealing the vapor barrier at the perimeter, to the earth floor tightly with landscaping pins, be a reasonable option (of course, sealing all pins). Then, I could seal against the center piers in the correct way, and tape all holes and seams. I've read about sealing the edges with sand bags, or pea gravel, but considering I have 228 ft of perimeter wall, that is a daunting task. Bottom line, does the seal have to be 'perfect' for the mitigation fan to be effective? Thanks.