# Replacing subfloor in 2nd floor bathroom



## Jniz (Feb 7, 2019)

Doing a remodel of our guest upstairs bathroom. I removed all the old tile and cement board to find a bit of expected water damage to the subfloor near the tub (we had a soft spot).

When I looked at the subfloor I saw it was only 1/4" Plywood. I believe it should be 23/32". I don't think I can or should just patch it with more 1/4" I need to remove the whole bathroom floor and replace it with thicker plywood even though this will effect my door height. 

Would love and appreciate any thoughts you folks might have.


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## chandler48 (Jun 5, 2017)

Just so we are on the same pew and same hymnbook, you say your complete subfloor system is 1/4" plywood? Highly unlikely. Can you post pictures of what you see? Yes, the subfloor should be a minimum of 3/4" Advantech or similar, based on the size of joists, their spacing and the total unsupported span of the joists.


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## Jniz (Feb 7, 2019)

Here is a picture of the floor with a section of the subfloor cut out, and some of the rot in the background. 

I also took a picture of the tile and cement tht was on the plywood that we already removed.


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## chandler48 (Jun 5, 2017)

You didn't have "cement board", but a poured substrate onto which the tile was laid. Very common in those days. I would pull all the subflooring, replace it with Advantech, then 1/4" Durock and then tile. Do the math to see how that matches the adjoining flooring.


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## Jniz (Feb 7, 2019)

Thanks. That is what I was looking at doing. Looks like it might be 1/8"-1/4- inch higher then the hardwood floor in the hallway after the tile goes in, but we will manage.

Thanks for the help


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## SPS-1 (Oct 21, 2008)

That's OSB in the first picture, not plywood. And I would be surprised if it is only 1/4"


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## Nealtw (Jun 22, 2017)

It doesn't matter what it us. get it out then look at what needs to be done to support the edges of the new floor and any walls that might be left hanging.


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