How to Do Rough-In Plumbing. When you are preparing to build or renovate a bathroom, there are certain standards that must be met when you perform rough-in plumbing. Although this can be a challenging endeavor, by following the proper procedures, you can get a bathroom plumb ready.

The Toilet

Step 1

Measure 12 inches from the wall (the finished wall) to the center of the toilet flange.

Step 2

Secure the flange to the sub-floor by using 3 inch stainless screws.

Step 3

Connect the elbow to the floor flange. The ABS elbow should be 3 inches in diameter and have a 90-degree angle.

Step 4

Position a vent at least 5 inches from the flange. The diameter of the vent can be 1 ½ inches.

Step 5

Consider including a cleanout for the toilet if you are installing it in a concrete floor or a cellar where the stack (sometimes called a "stink stack") goes into a crawlspace or the cellar.

Step 6

Make sure you install the supply for cold water 9 ¼ inches from the floor. The cold water supply should also be 6 inches to the left of the toilet and include a 3/8 inch (outside diameter) compression fitting.

Step 7

Fit a "closet supply tube" to the compression fitting with a compression ferrule and install a closet (a fitting that's tapered) to the other end of the tank's supply tube.

A Drop-in or Counter Top Sink

Step 8

Construct the drain so it is in the center of the sink and 18 ½ inches from the floor (the finished floor in this case).

Step 9

Use a 1 ½ inch hub as well as a 1 ¼ inch ABS "slip joint adapter" to install the 1 ¼ inch waste pipe. Fit the adapter on the tail piece that comes through the bottom of the sink.

Step 10

Put a 1 ¼ inch or 1 ½ inch vent with 5 feet of the "p-trap," or the pipe that goes up through the wall, behind the sink. Use a sanitary tee to attach the pipe to the sink's waste.

Step 11

Include a cleanout below the p-trap using a slip joint adapter as well as a union p-trap.

Step 12

Add cold and hot water supplies and make sure they are on the sink centerline. They should be 21 inches from the floor, and end with 3/8 inch compression fittings. Put risers of lav supply tubes on the sink faucets.

The Pedestal Sink

Step 13

Go below the sink when performing rough-in plumbing for pedestal sinks. When the sink is 32 inches tall, install the drain so it's centered inside the sink and 18 ½ inches above the floor.

Step 14

Create a vent in the same manner as with a drop-in or counter top sink. The cleanout will be the same as well. Hide as much of the drain as possible behind the sink's pedestal.

Step 15

Utilize 4-inch centers when you install the shut-offs. Remember to install the backing necessary to keep the pedestal of the sink upright.

The Tub and Shower

Step 16

Access below the floor to install the drain for the tub. The drain should be 1 ½ inches in diameter, and should go through the floor where it connects to the stack by means of a sanitary tee. The placement of the sanitary tee will depend on your joists. The drain for the shower is 2 inches.

Step 17

Establish a connection from the drain to the waste of the tub and the overflow, and install it before you install the tub.

Step 18

Decide on a style of stopper for the tub and install it.

Step 19

Attach the surround on the sub floor before you finish framing if it is in one piece. If the surround is in two pieces, you can install it after the framing, or during a renovation, as the pieces will fit through the door.

Step 20

Insulate and install a vapor barrier if the tub goes against an outside wall.

Step 21

Apply the stack as a wet vent, if it is at least 5 feet from the p-trap. Otherwise, go through the wall and use a 1 ½ inch vent.

Step 22

Check your local codes for the proper clean out on a tub installation. You might be able to avoid installing one, especially if the p-trap is inaccessible beneath the floor (as is often the case).

Step 23

Install the control valve before finishing the walls. The valve should be 54 inches above the finished floor as well as 15 inches above the rim of the bath tub. Install it 10 ½ inches above the rim if you have only a shower.

Step 24

Place a spout that includes a diverted 4 inches above the tub. You also can put the "tub only" install 4 inches above.

Step 25

Fasten the shower head 78 inches above the sub-floor, and make sure you connect the cold and hot water supplies to the control valve. Check for leaks by turning on the water. Measure 76 ½ inches above the floor and install the shower curtain rod.