Toilet Rough-in Sizes – Important Things to Know

Toilet Rough-in Sizes – Important Things to Know
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What is a Toilet Rough-in?

The toilet rough-in is the distance between the rear finished wall of a toilet and the center of the toilet drainpipe.

A toilet drainpipe is the pipe through which toilet waste leaves the toilet and connects to the sewer lines. Standard drainpipe are 3 inches in diameter although 4 inch drainpipes are also used

A toilet flange is installed on top of the drainpipe. The toilet flange which is also known as a closet flange is a circular pipe fitting which holds the toilet firmly on the floor.

how-to-measure-a-toilet-rough-in

Two bolts slotted on each side of the flange are connected to the toilets and tightened with washers and nuts. Often, the bolts are trimmed down and the nuts covered with plastic caps matching the color of the toilet.

If therefore a toilet has been installed and you need to measure the rough-in of the toilet, simply measure the distance between the rear wall and one of the two toilet bolts. You can also measure both sides for extra accuracy.

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Most toilets have a rough-in of 12 inches. It is however not uncommon to see 14 and 10 inch rough-in toilets. This is especially the case in old houses.

In order to correctly measure the rough-in of your toilet, you need to know the type of toilet you have. There are 3 types of toilets in as far us toilet rough-in is concerned:

  1. Standard toilet
  2. Corner toilet
  3. Rear discharge toilet

You will only need a measuring tape and probably a pen and paper to measure the rough in of your toilet.

How to Measure Toilet Rough-in of a Standard Toilet

While talking about toilet rough-in, a standard toilet is the one that is installed flush to the bathroom wall. These are the most common types of toilets.

In this case, you will need to measure the distance between the rear finished wall and the center of the toilet drainpipe. It is important I emphasize on the importance of FINISHED wall.

If you are taking the measurement from a stud wall, most often a ½ inch drywall will be installed. So if you get a 12 ½ inch rough-in from the stud wall the correct rough-in will in essence be 12 inches.

It is always important that you also take the measurement from the finished wall and not the baseboard. Doing this can give you an error of up to a ½ inch.

Again, if the toilet is installed, you can always take the measurement from the wall to the toilet bolt cap.

How to Measure Toilet Rough-in of a Corner Toilet

Corner toilets are compact toilet installed at the corner of a bathroom. They are especially installed in small bathrooms economize on space.

To measure the rough-in of a corner toilet, you will need to measure the distance between the finished wall of either of the 2 adjacent walls and the center of the toilet drain pipe.

Unlike a standard toilet, you cannot measure the rough-in of a corner toilet from the wall to the toilet bolt caps. When you do that, you will not account for the distance between the bolt cap and the center of the drainpipe

How to Measure the Rough-in of a Rear-Discharge Toilet

Waste in a standard toilet exit the toilet bowl through the bathroom floor and into the sewer lines. In a rear-discharge toilet, the waste exit the toilet bowl through the bathroom wall.

To get the rough-in of a rear-discharge toilet, measure the distance between the finished floor and the center of the toilet outlet pipe.

Can You Replace a 14-inch Rough-in Toilet with a 12-inch Rough-in Toilet?

You can replace a toilet with a rough-in of 14 inches with one with a 12 inch rough-in but you cannot replace a toilet with a 12-inch rough-in with a 14-inch rough-in toilet.

Think of it like a parking spot. You can park your car where a bus had been parked but you can’t park a bus in a spot meant for a car.

The one thing you will notice after replacing a 14 inch rough-in toilet with a 12 inch rough-in toilet is that there will be a 2-inch gap between the toilet tank and the wall. If you don’t mind the gap then you should be good to go.

If you however don’t like the idea of a toilet sticking out into the bathroom especially when you have a small bathroom, you could use TOTO Unifit Adapter.

The toilet Rough-in adapter will be installed on the toilet flange. The toilet adapters are specific to the rough-in you need to correct. A 14-inch rough-in toilet adaptor will therefore push the toilet back to the wall by 2 inches when being installed to a 12-inch rough toilet.

The bad news is that it does not work on all toilets models. Only a limited models of Toto, which are all skirted toilets are compatible to this adaptor. One of the most popular among those toilet models is the Toto Soiree.

10-inch Rough-in Toilets

If you have an old toilet with a 10 inch rough-in which you need to replace a with a modern toilet of the same rough-in, these are some of the best toilets with a 10-inch rough-in:

1. Toto Drake II Elongated Universal Height toilet

  • Elongated toilet bowl
  • 1.28 gallons per flush
  • Two-piece toilet
  • Toilet dimensions: 28.8 x 16.5 x 29.4 inches

2. KOHLER K-3889-0 Highline Comfort Height Toilet

  • Elongated toilet bowl
  • 1.28 gallons per flush
  • Two-piece toilet
  • Toilet dimensions: 27.25 x 17.62 x 30.5 inches

3. American Standard Cadet 3 Round Front Flowise Toilet

  • Round toilet bowl
  • 1.28 gallons per flush
  • Two-piece toilet
  • Toilet Dimensions: 26.2 x 17 x 29.1 inches

14-inch Rough-in Toilets

If you are looking to replace an old toilet with a rough-in of 14 inches with a new one of the same rough-in, this are some of the best 14-inch rough-in toilets:

1. KOHLER Wellworth Toilet

  • Round toilet bowl
  • Standard height
  • 1.28 gallons per flush
  • Two-piece toilet
  • Toilet dimensions: 29.62 x 18.25 x 28.75 inches

2. Kohler K-3949-0 Highline Comfort Height Toilet

  • Elongated toilet bowl
  • 1.28 gallons per flush
  • Toilet dimensions: 31-5/8 x 18-1/4 x 30-3/4 inches

3. American Standard 215FC104.020 Toilet

  • Elongated toilet bowl
  • 1.28 gallons per flush
  • Toilet dimensions: 30.38 x 17.38 x 30.13 inches

Conclusion

Knowing how to measure the rough-in of a toilet can save you a lot pain and time. There is no was feeling than buying a toilet only to find that it cannot fit in your bathroom. Most toilet have a rough-in of 10, 12 or 14 inches. The measurement you will get is not always accurate. An error of a ½ inch is tolerated. Just simply round off your measurement to the nearest rough-in.



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