Attic Remodel-No Plumbing-Where oh where to run 3" sewer

Ok. I am back again.

I am adding a bathroom off of a gameroom upstairs. The bathroom will be built in existing attic space. I have water, hot and cold, but no 3" sewer line. I have three full baths downstairs on slab on grade. Two of them I could drop the 3" line down their interior walls. One is at the very back of the house. Here, plumbing should be closer to the slab correct? The other in the middle of the house. Plumbing here is a little deeper and may be harder to get to. Either will work. The question now is do I bust up the concrete slab with a large hole and tie in from above the slab. I could do this in either bathroom. Or do I get someone to dig a hole and approx 6 foot tunnel under my house and punch a 4 inch hole thru slab and tie in pipes from underneath. This would be done to the bathroom in the back of the house. Closer to exterior walls. Anyone have experience with this?

Had a professional plumber take a look at my job. $1,600 just to run a 3" line down a wall and tie into main drain under slab. Yikes. Thats why I am back to doing this myself.

You guys have been great with all the info and I appreciate it.

Dave

One problem with the tunnel is that it will be hard to properly backfill it so it supports the pipe and the floor. I would vote for the slab unless you have a very expensive floor that will have to be replaced.

There is probably a footing around the house that is quite thick and may be 2 ft deep if you are not in a frost area; 4 ft deep if you are where it occasionally get to 20 below. You will tunnel under that footing, which is supporting your wall and roof. Maybe a structural problem, maybe not if your tunnel is only 2 or 3 ft wide.

Breaking concrete isn't that tough if it isn't reinforced, after you get the first hole through, and if it isn't more than about 4" thick.

You might want to go down to the local place where contractors hire illegals to do day-work, and get a couple of them with 10# sledges, a steel bar, and a mattock to dig out the concrete and earth on the first day.

If there are rocks near the surface as they are here in The Granite State, you may get some surprises you are not prepared to deal with.

6 ft tunnel under house

If this is you're approach,you have no buss. taking on this project

If you think $1600 is high, wait 'til you see the bill for digging a six foot tunnel under your slab. OSHA will be all over that job!


Seriously, this job is just a little beyond DIY. Get some help from a good licensed plumber, He will know what to do, and he will probably let you do a lot of the demolition and "grunt" work if you are willing. This will keep the cost down.