Ever since our new dishwasher was installed, our kitchen sink backs up. We do not have a garbage disposal. Do I need a special vent?

Ever since our new dishwasher was installed, our kitchen sink backs up. We do not have a garbage disposal. Do I need a special vent?

A special vent isn't needed. You have a partial blockage somewhere in your drainage. My bet's on the lateral, (horizontal) drain in the wall. Remove the "J" bend from the trap and send a snake up into the wall. You'll hit a elbo about 6" in but once past that you'll have a straight shot of about 5 feet to the sanitary tee and vent stack. Snake the drain line and I'll bet your problem will disappear. Good luck, Tom