Replacing house trap with cleanout; removing air inlet

D107

Preliminary to installing a CIPP sewer line on roots ravaged line, contractor needs to chop out a bit of the small trap pit to get the right angle to install the lining. In the process he recommends removing the old cast iron trap and air vent and installing a raised cleanout. He will then repair the damage from the chopout.

Before removing the trap I would like him to inspect all the house fixtures to make sure they are all vented propertly—whether through main stack or studor vents. I don't suppose there's a way or reason to connect the old cast iron air vent to the new cleanout?

I will have to check with my town to see if I need to pull a permit to do this, in which case this lining contractor—a journeyman plumber—has a licensed plumber he works with to get that permit. Obiously there will be some sheetrocking work to do after the vent stack is removed. Does this all seem reasonable? —see photos.

Also, do homeowners every install a hinged check valve that prevents waste from sewage from backing up into the house? I've seen them on apartment buildings.

Jamie Hall

Yes you need to pull a permit for that, and yes a licensed plumber has to oversee the work.

Now as to whether to remove the house trap or not — opinion has always been somewhat divided on that. The house trap does have the benefit that if you have dry traps on lines in the house, you don't get that good sewer smell. On the other hand, they can clog — though very rarely, unless people are abusing the water closets with things that ought not to get into them, or you are dumping a lot of grease or fat. Which you also shouldn't do.

The quickest and easiest way to find improper venting is with a smoke candle. The plumber should be able to do that.

D107

@Jamie Hall Thanks. Well the other choice is for the contractor to replace the old trap with pvc after the lining is done. In that case the vent stack can remain I guess, as long as he can get the angle he needs for the lining without removing it. With the trap removed, it seems to avoid sewer smell not only would all the fixtures have to be correctly vented but there should no pinhole leaks in the cast iron foundation vent (air inlet), connected immediate CI waste lines or nearby floor cleanouts.