Leaky toilet = rotten plywood [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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05-27-2019, 12:34 PM
Helping a veteran with his house. His toilet was loose for an extended period of time. When I went into the crawlspace and chiseled away the spray foam from under the subfloor, the plywood is completely rotten and easily scraped away (as well as a joist) for a good 2 feet around the toilet. He is lucky he did not fall through!

Looking from underneath in the crawlspace, you can see the hardie board under the tile.

I have replaced the rotted joist, and am looking at options for the tile to keep the costs down. He does not have any spare tiles. I am assuming finding a match for the 15" tile will be impossible. Hard to believe the tile is actually intact from above, but roped it off so they don't step on it.

1) If I cut away the tiles above the rotted plywood (wet saw with diamond blade through the grout(?)), place the plywood and replace the just the tile, I'll be left with tile with Hardie board attached to the tile. How difficult to remove the hardie board from the tile? Or can I just lay that tile (with the hardie board attached to the tile) on the plywood with thin set??

2) Totally replace all tile in the bathroom. would rather leave the plywood subfloor as it still has the spray foam. But removing the tile from the hardie board sounds like a nightmare...

Trying to do this the easiest and cheapest way. Cutting away all the sewage laced decay was pretty nasty.


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05-27-2019, 01:08 PM
Welcome back, Tom. :)

To get the rotted plywood out, you'll have to cut it back to the joists, and you'll want the patch to span over at least three joists. That'll mean cutting more tile and backer away from the subfloor.

The problem is, you never know how easy or difficult the demolition will be until you start. Then the question is, where do you stop?

Is the Hardibacker 1/2" or 1/4"? Depending on how it was installed, it may come up easy. Or you may be tearing it up in chunks no bigger than your hand. There's just no way to know for sure ahead of time.

How many square feet is the entire bathroom? Sometimes you can spend so much time and effort trying to get a section replaced, that in the end it would have been more efficient to just be able to tear it all out and start over. I know you want to keep the costs down, but your time is worth something, as well as knowing that the job was done well.

The big box stores always have some cheap tile on sale for a buck or less a square foot, and I bet if you go talk to the manager and tell him your situation, he might let you get some tile backer at a dirt cheap price, or for free. Especially since this is a veteran that you're doing the work for. If you're doing the work for free, that's another thing I'd mention.

05-27-2019, 01:09 PM
I just thought of one other thing: since he's a veteran, the local VFW might be willing to pony up for some materials. You might also check with a local church.

05-27-2019, 04:02 PM
Tom, where are you (or the vet) located? As Kevin said, there are many regional Veteran Service Organizations that may be of assistance.

Uh raah!

05-28-2019, 03:56 AM
Thanks for the info Kevin, the bathroom is 7x12 with 1/4" hardie backer. The good news - the Hardie was just screwed into the plywood, no thinset.

You are probably correct, in the long run - it will be easier to just rip up the tile with new Hardie.

Doing the work for free, already replaced an exterior wall with siding and fixing a lot of poor plumbing with leaks.

You would have thought that the bathroom would have had some unusual smells with the amount of damage - I was shocked. I would not spray foam around plumbing drains - especially toilet fixtures. You have no idea if it was leaking.

When he asked me, "I want to show you something - is this bad?" and swiveled the front of the toilet 2" to the left then 4" to the right, my heart sank...

They have another bathroom where I can put this on the back burner until
I finish the wall project and have more time.

05-28-2019, 06:00 AM
Good luck, Tom. It's a good thing you're doing. :yo:. :usflag:

05-28-2019, 10:01 AM
I'm in the midst of a very similar job myself (https://www.johnbridge.com/vbulletin/showthread.php?t=126992)

I found an oscillating/multi tool with a grout blade very effective at cutting out the tiles, then a wood blade for cutting out the subfloor.

05-30-2019, 06:25 AM
Thanks Jeff, reviewed your post & it looks like you had your hands full as well!

I used my multi-tool for the plywood, spray foam removal and investigating rot in the joists. Forgot about the grout attachment, so thanks for the tip!