How to Rough-In a Toilet

What You'll Need
Tape measure
Screws and screwdriver
Two adjustable wrenches
Ratchet wrench and sockets
Tubing cutter

The term "rough in toilet" means to set the plumbing of the toilet. In order to install a new toilet you need a rough-in measurement which is compatible with the toilet you wish to purchase. The toilet bowl’s hold-down bolts and the distance to the wall from these bolts is called the toilet rough-in. If these are compatible and line up with the waste outlet hole, you have the conditions to allow you to rough-in a toilet.

Step 1 – Measure Wall to Toilet Distance

Measure the rough-in by checking the distance from the hold-down bolts to the back wall. Using a tape measure, check this distance to ascertain the type of toilet you can purchase. The common design is for a 1-foot (12 inch) rough-in; the alternative is usually 10 inches. This is all done because it is imperative that the toilet match up with the drainage-pipe outlet. The other major consideration is whether the toilet will drain from the base or from the back.

You will now have the information to go out and buy the toilet of your choice within the range you are naturally restricted to due to your rough-in toilet measurement and drainage location.

Step 2 – Begin the Rough-in Toilet Installation

The rough-in toilet installation should begin with marking a line from the wall to a point 1 foot away from the wall and at least 15 inches from the nearest side wall. Also, if necessary, allow 22 inches from the wall in front of the toilet. The alternative distance from the back wall is 10 inches so adopt this measurement if this is the case.

Step 2 – Rough-in Toilet

Now simply install the toilet following the manufacturer’s instructions. It is recommended that you lay the flooring you require before installing the new toilet.

Fix a plywood base to the floor and center it over the drainage pipe outlet if it is in the floor and not in the rear wall. Fix the toilet flange which came with the toilet to this and secure the flange to the plywood base. Secure the toilet to the flange and plywood base. Use screws to make the flange secure. 

Step 3 – Connect the Toilet

Connect the toilet to the drainage pipe. Fix the toilet to the flange by mounting it on the flange mounting bolts and tightening the nuts firmly into place whilst being aware not to over tighten which can lead to the mounting holes cracking.

Run a cooper pipe for a water supply to enable the toilet to connect to it and also install a shut-off valve.

Connect the tank to the bowl by attaching the tank bolts first then locating and fixing them to the bowl using a wrench. Again be wary of over tightening. 

Step 4 – Finally

Finally, you will need to cover the plywood base with suitable flooring material to match or complement the rest of the flooring.