I am adding a shower to my existing 1/2 bath. to do the plumbing I can do the p trap and go straight over to the main house drain. Do I still have to have a vent??
Local codes may be different in each area. Check with your local building inspector. If there is already a vent because you have a sink and toilet, you could possibly tie into that for drain and vent. I remodeled recently and moved the kitchen from one side of the house to the other. Where I ended up placing the sink and dishwasher, was on the same wall as a bathroom I had installed 3 years ago, on the opposite side. This allowed me to tie into the drain and water in the wall, which already had a vent stack. Inspector was perfectly satisfied with this setup. So again, I would ask your local inspector. A permit is most likely needed, and would have to have an inspection for rough and final. Best to get the vent issue taken care of before rough inspection.