Toilet Drain Through Floor Joist

Where and how to drill joists for electrical cables or plumbing runs depends on what type of floor framing you have.

Toilet drain through floor joist.

Well you only need an inch of drop for every four feet for a pipe 2 1 2 or smaller. Do not even think to drill a hole for your toilet drain on your floor joist. Good luck with your project. The holes will have to follow a straight line that goes across the floor and has to either go up or go down so the pipe has a slope.

The holes must follow a straight line across the floor and must ascend or descend so the pipe will be sloped 1 4 inch per foot. Away from the top and bottom. A fall of 1 4 inch per lineal foot is the best slope for drainpipes. When you run your pipes through a joist you will have to be careful with your work.

How to install drain lines through the floor layout. If joists are 16 inches on center and pipes run across them at a right angle holes should differ in height by about 3 8 inch. 3 pipe is 3 1 2 od and 4 pipe is 4 5 od. Although notches aren t allowed in the center third of a joist s length you can drill holes anywhere along the length of the floor joist in that 5 1 4 in.

Step 4 cut the holes. Area in the middle of the 2 10 joist where the hole can go. While plain water will drain with. So if you ve got a 2x10 you ll be able to squeak a piece of 4 pipe through if you carefully centre it in the joists from top to bottom.

Mark where the overflow at the top. Keep the hole at least 2 in. And most abs toilet drain piping i ve seen is 4 not 3. That s only 4 over 16 feet.

From the top and the bottom if it s a dimensional lumber joist. That gives you a 5 1 4 in. The slope should be about 1 4 for each foot of pipe. The bigger hole you can drill on 2x10 it will be 1 inch and you need at least 4 try to build some how a bulk head downstairs if it is possible.

So your hole sizes will need to be a bit greater than that. And you can cut holes in the joists within the permitted range. Drill holes with a diameter of no more than one third the depth of the joist staying 2 in. Running drainpipe through joists calls for meticulous work.

So just measure carefully to maintain the minimum slope following the joist manufacturer s rules and you ll be fine.