Tempting, but you can’t glue PVC to metal


HomeHome / Blog / Tempting, but you can’t glue PVC to metal

Jan 25, 2024

Tempting, but you can’t glue PVC to metal

Q: On my top floor the waste stack has a hub with a 1 1\\2 -inch fitting with no

Q: On my top floor the waste stack has a hub with a 1 1\\2 -inch fitting with no threads. 1 1\\2 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 current plastic to cover the exposed dirt and walls without having to remove the plastic that's currently installed? -Jay C.

A: There's no problem with adding additional plastic sheeting over what's already there to cover up the bare spots. I’d recommend using 6-mil black plastic sheeting, which you can buy at any home center or hardware store. It comes in different widths and lengths, so just get whatever size roll you can easily handle under the house, the wider the better.

Overlap the new material over the old material by 12 to 24 inches. At the foundation walls, run the sheeting up the walls about 6 to 12 inches, and seal it to the walls using mastic, construction adhesive, heavy-duty sealing tape (duct tape won't hold), or a pressure treated nailing strip. Don't let the plastic get all the way up to the floor joists, since that can create a hidden pathway for termites; always maintain a minimum of 6 inches between the top of the plastic and the bottom of the joists/sill plate.

Q: I’m in the process of relocating my dryer vent and the new location will be going through my floor and into the basement. My question is; in order for me not to make a mistake I was thinking of installing a 3″ reducer in the floor and then attach the normal 4″ piping on both sides of the reducer, one attaching to the dryer and the other exhausting out of the house. Does this make sense or do I need to explain further? The reducer would be located in the wall and using the 3″ reducer pipe would give me a little more wiggle room when coming up through the basement into the wall and then 90 degree into the laundry room. -Kevin S.

A: You definitely don't want to use a reducer between the two 4″ pipes. What will happen at the reduction point is that lint will get trapped there, creating a potential fire and moisture problem. Even more importantly, that reducer will prevent a 4″ brush from passing completely through the ducts when it comes time to clean the system.

Either purchase a 4″ hole saw, which will allow you to drill a clean hole where the pipe passes through the floor, or cut a slightly oversize hole to allow you the wiggle room you’re looking for, then use a 4″ trim plate to cleanly finish off the installation. Trim plates are available wherever you buy your other ducting materials.

Q: Can you please explain me what is the difference between Product Warranties and Design Warranties ? -Kevin M.

A: A design warranty offers a warranty against a defect or a problem with the way something was originally designed, before it's actually made. A product warranty is a warranty against defects in the actual product itself.

Have a home repair or remodeling question for Paul? He can be reached by email at [email protected].

Sign up for email newsletters

Follow Us