Just like it sounds, to rough in is to do the basic plumbing install, to get it in place so the other stages of construction or remodeling can move forward. When those stages, like drywall and tiles, are complete, then the plumbing job can be finished. Here’s a step by step outline of a rough in for a toilet installation. Bear in mind that each situation is slightly different so this only provides a basic outline and list of considerations.
Step 1 – Find and Mark Your Location
Determine where the toilet is going to be positioned and mark its center on the wall. Measure out 13 ½ inches and mark the location, this is where the closet flange will be located. Center the flange on top of the mark and draw a line around the outside of it.
Step 2 – Cut out the Drain Hole
Cut the marked section out and position the flange in the hole with the edges sitting solidly on the floor. Ensure the two elongated slots are on the sides (your toilet bowl bolts onto the flange using these two slots) and screw the flange to the floor. Since the closet flange needs to be flush with the finished floor, you may need to put shims under the flange before bolting it to the floor if your are going to be using a raised floor (like ceramic tile).
Step 3 – Install Drain Piping
Underneath the floor install your drain and vent components. You want to direct the flow towards the main waste stack. Use a 3-inch long 90 degree turn fitting and run it into a 3x 3×2 Y fitting positioned so the 2-inch lead can be piped back to the main vent pipe. Continue the 3-inch piping to the main waste stack and connect into it with a 3-inch Y fitting.
Step 4 – Install the Supply Line
To install the water supply line run the water supply directly up through the floor or inside the wall near the side of the toilet tank that has the water supply link fixture on it. Position a “T” fitting on top of the supply line, with the water line going into the bottom of the “T”, the middle outlet of the “T’ facing out through the wall and the top of the “T” extending up in behind the wall.
Attach an 8-inch section of pipe extending through the wall to supply the toilet and attach a piece of pipe (about 12 inches long) onto this up pointing “T” side. Solder or attach cap fitting to this section to create an air chamber that will prevent “water hammer.”
Now that the plumbing us roughed in, you can finish the rest of the bathroom, install the toilet and hook it up to the drain and supply lines.
Some important considerations when installing plumbing
Drain Slope – The ideal slope for a drain is ¼-inch per foot. Too little slope means water (and solids) may not drain while too much slope could cause the water to drain away too fast, leaving solids behind and you can end up with clogged pipes.
Vent Angles – Proper angles on vent pipes are necessary. Vents need to angle upwards at a 45-degree angle or more away from level to ensure they won’t ever fill with water. A vent filled with water obviously can’t work
Cleanouts – Accessible cleanouts are required. Local plumbing codes specify where cleanouts are required in a plumbing system. No matter how well a system is designed and built, clogs can occur and you need to be able open up the drain and clean it out manually.
Comfort Room – People need space. For someone to comfortably use a toilet, a minimum of 15 inches from the center of a toilet to a wall or vanity on either side, as well as 18 inches from the front of a toilet to the facing wall should be provided.
**This article originally published here: http://www.doityourself.com/stry/rough-in-plumbing#.U1v1dvldWSo