# How to replace subfloor from BELOW w/out removing tile above?



## meanwhile (Dec 13, 2007)

Help! We have discovered that the sub-floor to kitchen has rotten from below. The floor joist are good and one section of sub-floor was given more strength by placing treated plywood on top of it and "picture frame" framing it in. But - several other sections are so rotted that we can see bits of the tile in the kitchen above.

I cannot afford to gut the whole kitchen and I do not want to crack the tile above.

One contractor told my husband that he can remove the WHOLE plywood sub-floor from below without removing any tile and he said he would not crack any tile either. I think he is either lying or just foolish. I don't see any way to completely remove the sub-floor under a tile floor and not have the tile fall to the ground or crack.

Is there a product that we could scrape or smear onto the rotten sub-floor similar to a bondo used in cars or like a wood-hardener product...that would harden and then provide the support to the tile, and then we would put a new sheet of treated plywood over that and frame it to the floor joist?

Thank you for any tips at all.


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## glenn amolenaar (Mar 3, 2007)

The only way to do it is remove all the bad wood , rotted wood just makes more rot, the best way is from top not bottom. Be careful and you can save tiles. The only way to do it from bottom is scap pieces which is a bad idea.

Glenn


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## wally (Oct 9, 2007)

This contractor is on crack run him down the road, noway can replace the subfloor from below..wally


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## Cash (Apr 24, 2007)

There are hardeners you can buy in home supply and hardware stores, but in my experience they aren't worth the money. From your description, the rot sounds pretty bad. Wish I could be more optimistic, but I think your best (only?) solution is remove and replace from above.


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## DAVID In Wisconsin (Dec 3, 2002)

The floor has to be torn out and replaced from the top. Your contractor is out of his mind. There are so many things wrong with his idea that I'm not sure where to start.


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## Beeman (Dec 29, 2002)

First question is what rotted the floor? Surely tile wasn't placed over rotted floor to begin with. I would bet when you rip out the tile and subfloor you might find damage to the top of the joists. There has to be a problem causing the rot and this must be fixed first. 
No, I don't see any way possible anyone could replace a subfloor from below. I think he'd probably cut pieces and stick them between the joists covering the problem and just make it worse.


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## rambler (Jan 20, 2004)

Like Beeman says, what caused the problem, have to fix the cause.

Then the top of the joists need to be looked at, likely they are soft too.

Really only way to do is start from the top down.

With the subfloor so bad, should be pretty easy to save the tile & reuse?

--->Paul


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## meanwhile (Dec 13, 2007)

Ouch - the house is for sale and we really did not want to rip out the whole kitchen. The tile was put down by a contractor about 12 years ago. He said he had put new boards down for sub-floor (which he did say was bad back then) but he lied and did not. We were new to everything and did not know to check and when he was later fired.......etc.....long story but he was finally fired - but we did not know to check under the tile that was already down.

Ouch - OK, thanks - we have another contractor and an inspector coming Monday to look and give opinions too. Thank you very much.


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## wvstuck (Sep 19, 2008)

If you have a contractor come in and make it look great for the sale, and a year later the repair is not holding so well and the contractor is out of buinsess... Who do you think is going to pay to repair a "patch and sell Job"... You will, in most states the buyer can come back on the seller if it appears they had knowledge of a problem and tried to cover it up for the sale.

There is no way to repair a sub floor without taking the floor up and repairing ALL damage. Sorry but it can't be done, and you may end up paying a lot more down the road, when you may not be able to.


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## meanwhile (Dec 13, 2007)

wvstuck: 
Thank you for the warning but no one is covering up anything in this case. You are so right and it is good to point these things out in case someone does not know but in this case, the buyers are aware and they have their own contractor looking at it too. 

I have to be able to plan to make the repairs myself if the current contract does not work out. If they go thru with the sale, then they will have to make the repairs any way they choose. I am preparing ahead of time in case I am the one who has to make the decision. 

My husband has an inspector and a contractor coming out Monday and we will see how bad it is then. Thanks for the tips everyone.


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## cfabe (Feb 27, 2005)

I will agree with the others who say it needs to all be torn out. There's no way you're going to be able to remove the subflooring from under the tile without disturbing it. Now if this is just a small area of the floor, it may be possible to remove the tiles without damaging them, cut out and replace the rotten subfloor, and then replace the tiles making it look okay. It might be hard to match the grout color exactly but it should be close.


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## Watcher48 (Aug 30, 2007)

Ya got to tear the thing out. Chances are you have no plastic down on the dirt in the crawl space. The moisture in the crawl space has rotted it. I would check your home owners insurance if you have it. I suspect you may find some other suprises.


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## Micahn (Nov 19, 2005)

If it is for sale get 3 prices and have in the contract that you know the floor is bad and let them take that out of the price of the home. That way you would not be out of pocket for the repair if money is tight.


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## Jim-mi (May 15, 2002)

If its not done right, your opening a can of worms that will sooner or later bite you in the back side . . big time.


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## Ross (May 9, 2002)

The first contractor was likely going to spray mold control, rip ply wood or OSB to fill the gap, stick it to the rotted wood underneath and sister a couple of 2x4's to the joists for support. Which isn't a repair..... its a patch.


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## meanwhile (Dec 13, 2007)

Hello and thank you again for all the tips and suggestions. The contractor we had come out agreed with all of you who point out there may be other problems and he also said the whole sub floor needs to come out BUT - he also agreed with the Buyers' contractor who claims he can remove the sub floor one piece at a time *without* taking out the tile! I was stunned since I really do not think they can take out pieces of sub floor and not crack up the tile or even the tile might just fall to the ground.

But - we have decided that we are not going to fix any of it and the Buyers can make their own decisions after they own the house. They sent the inspector back under there and so they know the extent of the problem and since they plan to remodel the house anyway - they can deal with it then.

If the sale does not go through, then we will have all the paper work to disclose to the next buyer. 

Thank you -


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## kjmatson (Jul 22, 2008)

Hold on a second, you have pressure treated plywood in your kitchen floor?


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## The Paw (May 19, 2006)

I am guessing that the subfloor might be 1 x 4 planking laid diagonally, in which case you might be able to take out one piece at a time without disturbing the tiles. Sounds labour intensive though, it might be just as cheap to take up the tile.


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## Farmerwilly2 (Oct 14, 2006)

My first thought was that the contractors involved were idiots. After berating myself for a snap judgement I will allow that they were the ones that actually looked at it so they are the ones that know what is actually involved. I suppose if the tile is layed on a cement backer and they think they can cut the backer free from the subfloor and cut the subfloor free from the joists then perhaps they could do it. Seems like a lot of work for a half-butt job. I agree with selling it 'as-is' and let the new owners decide what they want to do.


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## cfabe (Feb 27, 2005)

I've done a few tile floors using various systems (direct onto cement, plywood w/ cement board, plywood w/ Ditra membrane, etc. And I just don't think there's any way to do the job right and not damage the tile. The only way possible would be if an isolation membrane like Dirta was used, it may be possible to slide out the subfloor from underneath, but it would be such a cumbersome job that the labor costs would probably run up above what all new tile would cost. Plus those membrane systems are still pretty rare on residential construction.


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