Is it mandatory/recommended to apply cement on all threaded parts of a P-trap. I need to install a new one, and am wondering if I also need to get a plumbing cement. Also, if I purchase a P-trap with cleanout, is a cement necessary on a cleanout nut? (I would not, because otherwise the whole purpose of cleanout is undermined, whenever you need to clean the trap, you're going to have a hard time trying to unscrew it/)
Thanks.
Best Answer
You do not use cement or any sealant on the threads of a p-trap. It would not do any good and would bond the threads and so prevent adjustment. The purpose of the threads in these drain elements is to compress the joint. The seal is made by rubber or plastic ring seals or the faces of the two parts of the p-trap.