Need to remove concrete floor in bathroom

[john.moshell]

I recently bought a 1968 bungalow that needs some renovations and updating. One of the bathrooms has a crack in the concrete floor where the tub meets the wall. I chisled out the 3" thick piece of concrete that was cracked and noticed that there is severe water damage to a joist that sits below the slab. I believe the previous owners kept using the shower (only one in the house, so it got plenty of use) and let water seap down in the crack.

So....I would like to pull up the concrete slab to find out what I am up against. My question is, what is the easiest way to get this concrete up causing the least damage to what's underneath? I have noticed a lot people just banging on it with a hammer, but I am scared I might be adding weight to the weak joists below. Cutting the concrete is also an option I guess, but do you just set the saw to not cut more than 3" (slab thickness)?

Any suggestions would be helpful. I jumped head first into this project. This is my first house and it was a foreclosure, so I have lots of work ahead of me.

......Thanks in advance for the responses.

[raven]

In short: unless you really _really_ have to, you don't. Inspect underneath for plumbing and elctirical lines and turn them off or reloacte them as you are able and then poynd away. If somthing underneath is rotten and breaks, well, it was going to need replacing anyway, so you've just started on that demo a bit earlier than you were otherwise going to.

Now obviously, if the beams involved are doing major load carrying and are in danger of causing some sort imminent collapse, then you don't want to just start banging about, but then you really oughtn'y be doing _any_ work in the area untill you get things shored up or otherwisee braced.

But for some possibly rotten wood under a bathroom? Just hammer away.

John

[kevin]

I don't get it at all. Normally, "what's underneath" a concrete slab in a home is just dirt and gravel. Is there a basement underneath this concrete floor? If so, you would just go down and look at the joists from below, so I'm assuming there is NOT a basement or crawl space.

The wood you are finding down there could be bits of the wood they used to make the frame into which the concrete was poured. It serves no purpose now at all, and is fine just rotting away under there, since it is buried in dirt anyway.

Now, cracks in concrete are inevitable and unavoidable. How bad was the crack? Just a hairline, or could you slip a pencil down it/ Or more?

Certainly make sure your tub is not leaking, but before you go ripping out your slab, maybe you can fix this problem by (a) ignoring it because it isn't really a problem, or (b), just patching the one spot from above, sealing the area, and making sure the tub isn't leaking anywhere.

-Kevin

[johnnymo]

Good suggestions. I guess I can provide some more info that I forgot. I do have a crawl space and I can't see concrete from the crawlspace, so it was poured in the house and not just inserted as a whole there.

The "crack" basically separated a corner (which I removed to find the rotten board underneath). The joists look ok from the bottom, but that one area that wasn't properly sealed definitely needs replacing. I figured since the slab is missing a corner and the area needs repairing, I could be pro-active and remove the slab.

Thanks for the suggestions....I can already tell this is going to be a fun task.

[Norminn]

A very puzzling scenario! You have the tub pulled out and found a concrete slab beneath it and on top of wood rafters? Tub drains go through the slab? Whole bathroom has concrete slab floor? Any chance it is just an old concrete shower pan that someone put flooring over and put a tub on top? What is there in the crawlspace that comes THROUGH the slab? An old shower pan would be a very likely place for leaks and rot, but I would hack away at a floor not knowing where I'm going.

[Speedy Jim]

Sounds to me like you have a cement subfloor. Wooden "slats" are laid between the joists to create a base for the concrete mix, which may only be 2 to 4" deep. The mix may have steel mesh in it for strength. The whole system forms a very rigid base for ceramic tile while not overloading the joists.

Jim

[trader4]

You can inspect joists and structure from the crawl space below and you say it looks OK. So, why demo it? If there is only a small area of rot damage and it can be repaired, I'd focus on doing that, not creating a bigger project.

[raven]

He's saying "slab" but what I think he's looking at is a floor that was done as a mud job, (where instead of concrete backer board, and layer of tar paper expanded steel and a dry mix of concrete is put over the subfloor).

Still, leaving that "slab" intact and just work on the damaged area is a good point.

John

[johnnymo]

Yea, so because I pulled that corner piece out which was cracked and had separated from the "slab" I can tell that the concrete measure 3" from wood to the top of the concrete. The top of the concrete is flush with the rest of the house's subfloor. It is flush with the kitchen's subfloor and the hallway to the bedrooms. The cast iron tub is sitting on regular diagonal wood subflooring which is also flush with the top of the concrete.

Can the concrete be poured between the joists and over the top of the joists by a half inch making it flush with the rest of the house. If so that would suck trying break that concrete out of there.

I obviously need to look at it more from the underside tonight to figure out if this is going to be worth it or not. Let me take a look tonight. The other bathroom (1/2 bath) only has a two inch slab and is in good shape.

[JimL]

Leave it alone and only patch what needs patching.

[Italian]

You have already gotten some really bad advice so I thought I would chime in.

"and noticed that there is severe water damage to a joist that sits below the slab"

Any time you have water damage to wood you must be able to see the total wood area to asses the exstent of the damage there is no other way of doing it. This is a very odd situation but I have seen this concrete between joists before. Unfortunally it is a method that is full of problems. If you are going to do this house right take this whole thing out in this bath and the other one, examine the joists, repair as needed and put in a real sub floor. Chances are based on the age of the house and the fact that you have a crawl space the floor joists are probably sitting on pier blocks. If there was continued water under the house you could have pier blocks that have shifted or soil that has eroded out near a block or some other damage from the water under the house. This all needs to be checked out before you just put a "band-aid" on this floor because if there is something down there it will come back to haunt you.... Yes you can do it another way but this is the right way.....

I have

not cut more

Chances are you do not have a gas saw and will just be using a circular saw in which case you will only be able to get about 2 1/2 inches down with so I would not worry about that. I would make several cuts in the concrete first dividing the areat up into about 18" sections. then use a "sledge hammer" to break the concrete. Start in a corner or the edge of the part of the floor that is already missing and work backwards....Concrete breaks very easily if it has some where to go. First hit the crack in the immediate area to the piece that is missing then on the very edge of the part that is already broken off. Repeate this sequence till you have removed it all. remember allways hit the concrete on the cuts closes to the piece you just broke off and then about 2 or 3" in from the edge. If you start in the center of the floor or in the center of a slab of concrete it will take yo forever because the concrete needs space to break. When taking out concrete always start on an edge NEVER in the middle

[e-mail] wrote:

[johnnymo]

Well....I examined the underside of the bathroom a little closer last night. It appears that about 3 subfloor boards are not looking very pretty. I will feel more comfortable pulling out the concrete to get a good assessment and fix what needs to be fixed.

I guess I will try the sawing method. It sounds a little dusty, but I guess it is the easy way and then bang out the cut pieces. I guess there is recommended blade for cutting tile/concrete?

Thanks for the suggestions. It is going to be fun. Wish me luck.

[Italian]

Use a good quality Diamond blade splurge on this blade believe me it is worth it. To keep the dust down have a helper spray (with a garden hose or pump sprayer) a small stream of water onto the blade while cutting...not too much just enough to keep the dust wet you will catch on quickly how to adjust the stream of water..

Yes you can use a carbide blade to cut c> Well....I examined the underside of the bathroom a little closer last

[kevin]

I have never seen or even heard of such a crazy way to do a subfloor. But still I wonder if you aren't making this too hard. Lets assume you want to remove the concrete. You seem to indicate that it is sunk about

2 1/2 inches down into the joist bays, and then comes up about 1/2 inch over the top of the joists. It must be resting on something since you can't see the concrete from the crawl space. I'm going to guess that there is some wood slats of some sort below the concrete, since that 1/2 inch lip would not hold the concrete so great.

Can you go into the crawl space and just cut out the rotten and remaining slats. Being careful of course to not let the concrete fall on you while doing this. After, you have just a 1/2 of concrete on top of each joist. Bust that up, or cut it, and the whole bay would fall down into the crawlspace.

But I am probably missing something given the convoluted history of this thread. Good luck anyway. And get some pics will ya already.

[Art]

It may be much thinner. My mud base is probably an inch thick.

[johnnymo]

Done....thanks for everyone's suggestions. I took a sledge hammer to it. Since I had the missing corner piece, the concrete started to separate nicely soley focussing on that area first. I did kind of starting hitting at the slab from straight above, which ended up going straight through the rotten subfloor below, so I modified my method and started swinging more at an angle toward the areas that I had already removed and it worked much better. Probably took me an 1 hour and half to remove a 5'x7'x3" slab. Joist look good, subfloor has got to go around the tub.

Thanks again for the suggestions.

[raven]

Told ya.

You're welcome and thanks for letting us know how it came out.

John