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Installing a new toilet on old fashioned plumbing

Reviewed by:
The Old House Web

My house was built in the 1940s. The existing toilet has two tie-down bolts on each side of the base. As far as I know, new toilets only have one tie-down bolt on each side. If I want to replace the old toilet with a new one, how do I solve this problem? Can I use only one bolt on each side?

A toilet is connected to the waste line with something called a closet flange. This is a ring with a number of holes and slots around the perimeter. It's attached to the end of the waste line, just where it comes through the floor. The holes are used to screw the flange to the subfloor, and the slots accommodate bolts that make the connection with the toilet.

When everything is assembled, the toilet is attached firmly to both the floor and the waste line and all is well. But unless the toilet can be bolted to the flange, you have a problem.

You're right, modern toilets are manufactured with two holes at the base, one on either side. It's possible, but somehow unlikely, that the old flange will work with a new toilet. But you can check.

After you pull the old toilet, look at the bolt pattern on the closet flange. If two of the bolt holes are opposite each other at the center of the waste line, you may be in business. If not, a new toilet won't line up correctly with the waste line.

The other key is the distance between the wall behind the toilet and the center of the waste line, which is called the rough in. For modern toilets, this is typically 12 inches. If this is not the case in your house, there are a couple of options.

One is to remove the existing closet flange and replace it with a new one. In this era of plastic pipe, components are simply glued together with PVC cement. That makes repairs pretty simple. With a house built in the 1940s, the waste line is probably cast iron, and the closet flange may have been joined to the waste line with melted lead.

This may seem ridiculously antiquated, but there's really no end to the plumbing mysteries you can uncover in an old house. We once discovered, during a bathroom remodel in an 18th century house, that all of the waste lines were made entirely out of lead.

To solve some of these vexing problems, the plumbing industry has developed a surprising variety of specialty parts and fittings. There may be a repair flange or spanner flange that suits your situation.

Of course, the easiest thing to do here is call a plumber. He or she will know how to deal with the problem and, as important, have the right tools. But if you want to tackle this yourself, take a photograph (even if it's on your cell phone) of the existing closet flange. Measure the rough in. Then go to a good plumbing supply house and ask about a repair part or adapter. If there's a simple fix, you can do the repair yourself. If it's more complicated, call in a pro.

Just don't give up on the idea of installing a new toilet. That's the right thing to do.

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