The Roof! The Roof! The Roof is All Moldy!

Our caller at the top of Hour 2 has a low-pitched rock roof on her 1950s-built house that has never been replaced or redone, and now they’ve found mold up there! How serious could it be and what's the treatment to repair it?  Next up, a listener needs to know if she can place epoxy or acrylic over a heating element for a radiant-heat floor.  Morris has an old house built in 1951 that suddenly has plumbing issues, particularly a leaky kitchen faucet. Apparently, the anchor valve is frozen, so how would he go about fixing all these issues?  If the final caller were to install carpet as a stair runner, does it have to have a finished edge, and does it have to be a certain kind of tack board? See omnystudio.com/listener for privacy information.