We live in a 1960's single floor concrete slab house with concrete block interior/exterior walls. We had to replace the pipes under the slab in the kitchen and currently still have the floor torn up waiting for better weather to start the floor repair process. The thought occurred to me about putting in an additional vent to help with the constant clogging/blocking issues we always had and the previous owners always fought with (plumbers always blamed it on poor venting). The sink is on an outside concrete wall and currently has a PVC Air Admittance Valve. The nearest "Aesthetically" safe area to put a roof vent in is about 10ft away across the room, and about 15ft away from the 4" main. This sink is the only item on this drain line to the 4" main. The pantry in the picture runs from floor to ceiling and there is an existing clean out we would wye off of for the vent. All plumbing from the trap to the 4" is 1.5".
Would this help or make a difference in the plumbing situation for this run? A vent from the sink area would either need to go through the counter top and a cabinet or out the concrete wall and up the back of the house, through a soffit and then roof right next to our back door.
Best Answer
In my area, a kitchen/bath waste arm must be no more than 3ft long unless an air admittance valve is used at the fixture. If an air admittance valve is located 10 feet away it won't do anything.