Q: On my top floor the waste stack has a hub with a 1 12 -inch fitting with no threads. 1 12 inch PVC slides in snug and tight. Can I glue it? -Jim T. A: You can’t glue PVC pipe directly to metal pipe of any type. PVC cement creates a solvent bond with plastic only, and doesn’t adhere to metal. If your code allows it, the pipe can be inserted into a rubber seal that fits inside the hub, then sealed in place with a sealant specifically made for this application. A retailer of plumbing parts should have all the pieces you need. Once again, you need to be sure that your plumbing codes allow this type of insertion seal. If not, you may need to cut off the hub portion of the old fitting and then use an approved band clamp to join the two pipes. Q: I smelled a moldy type smell in my 22 year old house. When I went underneath I found a number of areas not covered by plastic. That exposed earth did smell moldy, and appeared to have a crust of some sort on the dirt. I also noticed the plastic sheeting did not go up the walls at all. In a few areas dirt and tiny roots have seeped through. The ground was dryer than I worried it might be. Can I put additional plastic over the cu...