Does shimming a toilet risk cracking the base?

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Neil.Steiner

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Question:

With my toilet sitting on the flange, without a wax ring in place, I've found that I can place two 1/16" metal washers at 1 o'clock, and one 1/16" metal washer at 3 o'clock to eliminate all wobbliness. I think the washers are zinc or something, but I realize I should replace them with plastic. My question is whether the localized pressure of the washers on the base could lead to the base cracking.

On this site it looks like people use shims all the time, but I wanted to solicit your thoughts first. It occurs to me that if I only have to place shims in two places that are fairly close to each other, the rest of the base must be contacting the floor almost everywhere else, so perhaps there wouldn't be that much pressure where the washers are.


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Background:

I took my first stint at replacing a wax ring on a toilet that use to rock just barely front to back. (The old wax ring had long since disintegrated.) From things that I read, I thought that the rocking might go away when I replaced the wax ring, but it did not. So I removed the new wax ring to identify what I thought might be a bad flange.

Upon inspection, the flange looked great to my untrained eye. The only issue was that the closet bolts had bent the flange upward a little. Thinking the flange was metal, I marveled at the force necessary to do that, but I now believe the flange to be some kind of plastic. (It doesn't sound like metal when I tap it with metal.)
 
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Shimming a bowl is pretty common. Shimming the back of the bowl typically works best. Your flange looks to be plastic, and should be secured to the floor. If you set the bowl down over it, check to see if it needs shimming.

shimming.jpg


Here the bowl is shimmed and the cut off.

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Rubber shims are easier to work with.

With your flange, I would think single wax ring without a horn, A regular wax ring.
Clear caulking around the base when done, leaving some out at the back.

How in the world would someone break a toilet bowl? I can't even imagine that and I have a good imagination
 

Jadnashua

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Keep in mind that the toilet bolts are more for alignment than really holding it in place, especially if it's over tile or wood or other solid surfacing. When setting the toilet, use your body weight to compress the wax, then snug up the bolts rather than cranking down on the bolts. Then, use some sealant around the front 3/4 or so of the base (leave the back open) and that will hold things in place. Do not use silicone as that will glue the toilet too tightly to the floor, but one designed for bathrooms. DAP makes one (used to be called Polyseamseal until it was bought out).

The sealant does two things:
- prevents crud from getting underneath the toilet where it's hard to clean
- helps to hold it in place (a vinyl floor will compress and help hold it, but wood or tile won't without excessive pressure being applied)

FWIW, I usually use coins, as I often have a variety in my pocket and it's one less trip to the store.
 

Neil.Steiner

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@Obama the Plumber, Thanks for the suggestion to use a regular wax ring without the horn. I didn't realize that the horn is typically only used when stacking two rings.

I'm also puzzled about the caulking/sealing, and was under the impression that the code here in Virginia did not require it. In any case, none of the three other toilets in my home are caulked at all, and at least two of those installations were done by licensed plumbers. But everyone on on this forum seems to advocate caulking or sealing the front 75%-85%.

As for how someone would break a toilet bowl, I've seen so many warnings against over-tightening the closet nuts, that I assumed the base might be more fragile than it appeared.

Oh, and my flange is not screwed into the concrete floor, but it seems to be held sturdily in place. (Could it be glued?) I don't actually have any idea how it's attached, nor do I know how this is generally done in the case of concrete.
 

Neil.Steiner

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@jadnashua, Thanks for the Polyseamseal suggestion. I didn't intend to use any sealant, but it would seem like everyone else on this forum agrees with you.

I can't imagine that the sealant would prevent any leaking out from the toilet base, given the gap at the back, so I guess it's primarily as you said to hold the toilet in place. (Sounds to this DIYer that it's done more as a best practice than as a code requirement.)
 

Terry

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Well I did break a bowl in the 70's, one of my early installs. I am more careful now. But also because if it's a plastic ring on the flange, you can also break that, and also maybe pull the closet bolts through too. I like to lock them down to the flange with a washer and nut and then the second set of washer and nut with the bolt caps. I go pretty careful on them now.
 
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