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Tree79
Concrete slab under 2nd floor bathroom

I just bought a 100 year old house and an in the process of gutting out the second floor bathroom. I have discovered the subfloor is a 4" slab of concrete. I am wondering if it would be a good idea to remove the concrete and install a wood subfloor. It really isn't hurting anything other than being super heavy. I will be moving the stool and bathtub around so I'll have to cut a couple new holes to run the plumbing but beyond that I
Was questioning the pros and cons of keeping it. Thoughts?

dj1
Re: Concrete slab under 2nd floor bathroom

Without seeing it, it sounds like removing the slab will not be a bad idea.

How is the slab supported? I've seen a lot of 2" light concrete on second floors, for sound proofing purposes, but a 4" slab?

Can you take pictures? if you do, load them up to a host like photobucket, then post the link here.

HoustonRemodeler
Re: Concrete slab under 2nd floor bathroom

This sounds like a mid century classic "mud" floor. Many times they deteriorate around the terlit. Sometimes they crack.

If yours is in fine shape AND you can handle the added height of tiling over it AND you are not changing the layout of the bathroom, you are good to tile over it. Mapei EcoPrimGrip is designed for this purpose.

But we can't see from here.

Tree79
Re: Concrete slab under 2nd floor bathroom

Took some pics but was having issues navigating photobucket. Confirmed there is approx 4" of concrete. Started pulling tile up and along with a very strong urine smell in thin set by toilet there are two cracks running the width of the bathroom floor as well as about a 2 sq ft corner cracked where the tub will go as well as what appears to be a multi timed patch job in front of the stool. Cracks were not known until I pulled up the sticky square tiles that were placed over the original tiles. Pretty much decided because of those cracks to completely remove the concrete and put plywood down instead.

HoustonRemodeler
Re: Concrete slab under 2nd floor bathroom

Removal is your best bet as the wetted ceement may very well have rotted the joists.

Let us know what you find.

Mastercarpentry
Re: Concrete slab under 2nd floor bathroom

With the cracking, removal is the only option. Whatever structure it once had is now gone and the cracking will only get worse taking whatever is on top with it. Be prepared for lots of surprises along the way- this ain't going to be a small-budget job, just a necessary one.

Phil

Re: Concrete slab under 2nd floor bathroom

The tiles appear to be set directly into a 4" thick concrete slab

LindA
Re: Concrete slab under 2nd floor bathroom

We have a similar issue but the "cement" under the old tile is a mixture of brick, rocks, and other debris and is about 6 inches thick we are removing it What a mess. what should we put to replace the "cement"?

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