Question about grouting tile under vs. around toilet

mitri89March 14, 2010

Is it okay if the tile underneath the toilet is not grouted? In 3 of our bathrooms for our new construction home the tile was laid about a month ago but not grouted. In the meantime the plumber installed toilets. Now the tile guy is ready to grout and is saying it's okay to just grout around the toilet instead of removing the toilets and grouting the tiles underneath. Is this really okay, or is there a reason we should insist that the toilets are removed for the grouting?

Thanks so much!

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No way. I'd lift the toilet. If the wax ring begins to fail, no grout means major water damage, whereas you have some wiggle room with grout.

    Bookmark   March 15, 2010 at 1:02AM
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That's what my gut was telling me, but I just wanted to be sure. We will insist that they be lifted. Thank you!!

    Bookmark   March 15, 2010 at 1:20AM
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It doesn't hurt anything not to grout under the toilet, but that's not how it SHOULD be done. Why the plumber installed the toilets over ungrouted tile in the first place is another issue. The big question, though, is why did it take a month for this guy to come back and grout?

    Bookmark   March 15, 2010 at 9:04AM
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It is a huge mistake not to grout under the toilet. Speaking from prior experience I can tell you story after story of leaky toilets and the nasty damage they do to a home over the years going unnoticed. Lets look at how a toilet should be installed and what happens over time so you understand why it needs to be grouted.

A toilets (WC) flange should be installed on top of the finished floor. This is rarely seen in renovations as most plumbers are not aware of the finished floors height and aren't travelling around with plywood in various thickness and don't take the time to build "Doughnuts" to raise the flange.

Typical Install Number One;

With this said in most cases the flange is recessed below the height of the finished floor. Toilets are designed to have aprox 1/8" to 1/4" clearance from the flange and their underside. If the flange is installed on the subfloor and the tile setter installed 1/2" plywood, Ditra, Thinset and tile you have added nearly an inch if not more to this equation.

Rarely again do you see #10 or # 12 screws used as most guys have #8 screws hanging about. In this typical set up an if the hole drilled for the WC flange was drill perfect you will get 4 screws biting into 5/8" of plywood (or worse OSB). The plumber will add extenders or double up on the wax rings. Over time with many uses and flushes often these built up rigs start to leak. With a little moisture these flanges start to fail as the screws start letting go. Then the leak is greater and you get the picture.

Install Number Two;

This time you have a perfect install. The flange is sitting on the finished floor and the flange has been secure with 2 1/2" screws and is biting into over an 1" of built up subfloor below the tile.

Your plumber uses one standard wax ring and your good to go - Problem....

The problem is you bought your toilet from a box store. Box stores bet down suppliers for cheaper and cheaper product. Many products sold in the box stores are not made to the same specs or standards as those sold through regular plumbing channels. Often a toilet from a box store will rock when sitting on flat floor.

Your install was tight day one but hidden below was a small leak - not much a trickle with every flush. Most people don't know that grout is not waterproof - it's not (most grouts that is). So this leak under your toilet goes on and on and on.

A better install;

Same as above but you check for rocking toilets at the box store or even for that matter at your plumbing supplier. Take it out of the box. Sit on it. Does it sound funny when you tap it? Does it rock? Is the glaze perfect? Check and then check again - this takes maybe 2-5 minutes of your time and can save you thousands and thousands down the road.

Install an extra layer of plywood below the subfloor between the joist so that when the WC flange gets screwed down you are screwing into 1 1/2" of wood. Spray the underside of this area to seal any voids with spray foam. Use a good silicone and seal any rough spots from above after tiling.

Install that toilet and flush it 10 times back to back and inspect for leaks. If you have a WC flange that can't move and the toilet is sealed there is no way of it leaking. Don't use silicone all around the base of the toilet as this traps any future leak from escaping under the toilets backside. Check this area when you clean from time to time and never let a toilet rock - if it's rocking it needs to be looked at!

Now imagine that this area is not grouted under the toilet - the water has a clear path to run under the tile and spread throughout the room or worse travel down the back wall and start forming mould on your son's bedroom wall. Maybe the path runs 10 feet sideways and starts soaking a support beam - bugs love wet wood and they move in. 10 years later you want to install new toilet and spruce up this room because it just has a funny odor and you discover the leak, the mould and worse that your homes structure is compromised.

Worst case scenarios I know - but each is a repair I have done for clients over the past 7 years. We get one a year and after each one I look for more and more ways of preventing this from ever happening.

Treat water as your homes number one enemy because it is, never let a toilet rock, always set the flange on top of the finished floor, never silicone the whole toilet base to the floor and always grout underneath your toilet.

Every time - Every job.


John Whipple

"When it's perfect - it's good enough."

    Bookmark   March 15, 2010 at 10:39AM
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Thank you both. They are going to remove the toilets and grout underneath. I appreciate the information you provided. It makes total sense! Thanks again!!

    Bookmark   March 15, 2010 at 3:31PM
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