To Remove Concrete Slab in Bathrooms?

fletch7 · 08-03-2011, 12:50 PM

I am currently in the planning phase for two bathroom remodels on the second floor of my house that was built circa 1910. In addition to many other efforts, I am redoing the tile floors. The tiles appear to be set directly into a 4" thick concrete slab. I've been able to knock a few of the tiles loose with just a hammer and chisel but others just fractured with the bases remaining attached to the concrete. I will likely rent a chipping hammer to get down into the surface of the concrete but now I am questioning whether or not to just take the whole concrete slab out as well. Is this advisable to remove with a sledge? The plumbing (to radiators, toilet, sinks etc) running through the concrete will be easier to deal with if I can create a new subfloor. Also, I will be alleviating thousands of pounds of load from the joists which have bowed over all the years (probably due to creep from exposure to leaks in the bathrooms). What I definitely don't want to do is destroy the plumbing that I wish to keep in place.

Ron6519 · 08-04-2011, 03:42 PM

Quote:

Originally Posted by fletch7

I am currently in the planning phase for two bathroom remodels on the second floor of my house that was built circa 1910. In addition to many other efforts, I am redoing the tile floors. The tiles appear to be set directly into a 4" thick concrete slab. I've been able to knock a few of the tiles loose with just a hammer and chisel but others just fractured with the bases remaining attached to the concrete. I will likely rent a chipping hammer to get down into the surface of the concrete but now I am questioning whether or not to just take the whole concrete slab out as well. Is this advisable to remove with a sledge? The plumbing (to radiators, toilet, sinks etc) running through the concrete will be easier to deal with if I can create a new subfloor. Also, I will be alleviating thousands of pounds of load from the joists which have bowed over all the years (probably due to creep from exposure to leaks in the bathrooms). What I definitely don't want to do is destroy the plumbing that I wish to keep in place.

I would think that, that age plumbing would be replaced when you did the bath. The supply and drain pipes especially. Switching out the heating pipes would also not be a bad idea.
I'd try to minimize traumea to the floor and walls as there are things next to and under this room.
You might find a pour break at the joist tops on this floor. Older baths I've worked on had cleats attached to the joist and 1x4's dropped in and the bay filled to the top with concrete. The tile guys would raise up the concrete to the finished height while installing the tiles.
Once you got to the joists, you could work the seam(between the 2 pours) and the concrete would come off pretty easily. The concrete in the bays would just lift out.

fletch7 · 08-04-2011, 05:03 PM

Thanks for your input. I wondered how the builders could have possibly set the tile on a relatively large concrete slab without it drying. It makes sense that it was done in stages. As far as the plumbing, I will be replacing the supply and drains, but planned on keeping the heating system unchanged. Just didn't want to mess with an additional system unless there is a reason to.

Bud Cline · 08-04-2011, 05:06 PM

You may find that your floor joists have been hatcheted ( I can explain that if need be) and will need to be repaired before you can go back with your new subfloor.

How will you regain the height?

The sub floors you have now are in fact the absolute best method of installing floor tile there is. It just isn't done that much these days. There are easier lighter weight methods but they aren't as good as what you already have.

If you joists are bowed now they will be bowed when the new subfloor is installed if you don't repair them.

Why can't you leave everything as is and tile over it?

Ron6519 · 08-04-2011, 06:20 PM

Quote:

Originally Posted by fletch7

Thanks for your input. I wondered how the builders could have possibly set the tile on a relatively large concrete slab without it drying. It makes sense that it was done in stages. As far as the plumbing, I will be replacing the supply and drains, but planned on keeping the heating system unchanged. Just didn't want to mess with an additional system unless there is a reason to.

You would need to see the heating pipes condition before deciding what to do. Replacing some pipes under a slab now is easier then doing it later when steam is rising through the floor and water is coming through the ceiling below.

fletch7 · 08-05-2011, 09:09 AM

Quote:

Originally Posted by Bud Cline

You may find that your floor joists have been hatcheted ( I can explain that if need be) and will need to be repaired before you can go back with your new subfloor.

How will you regain the height?

The sub floors you have now are in fact the absolute best method of installing floor tile there is. It just isn't done that much these days. There are easier lighter weight methods but they aren't as good as what you already have.

If you joists are bowed now they will be bowed when the new subfloor is installed if you don't repair them.

Why can't you leave everything as is and tile over it?

I suppose I should have mentioned that the existing tile has a number of cracks running across the width of the floor (perpendicular to the joists). The concrete beneath is cracked as well. I don't think it would be a good idea to tile over any of this. At the very least, I think I need to remove the existing tile, relevel the floor and then lay new tile. Would the cracked concrete below cause problems? My thought was it probably cracked early on and is more stable now.

If I removed the concrete all together, I planned to regain the height with the appropriate thickness stock laid perpendicular to the existing joists. This will be more difficult if the joists are hatcheted. How would you suggest I repair the hatcheting if it is there?

The sagging issue was more a factor of adding weight. I will be adding a new tub and laundry area to the expanded bathroom. I just thought removing some load and adding another would prevent further sagging.

Bud Cline · 08-05-2011, 09:18 AM

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I suppose I should have mentioned that the existing tile has a number of cracks running across the width of the floor (perpendicular to the joists). The concrete beneath is cracked as well.

Well yowah! I suppose that would have been some useable input.

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If I removed the concrete all together, I planned to regain the height with the appropriate thickness stock

Appropriate thickness stock, appropriate thickness stock, h-m-m-m-m, I guess I don't know what appropriate thickness stock is.

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This will be more difficult if the joists are hatcheted. How would you suggest I repair the hatcheting if it is there?

Sistering maybe.

fletch7 · 08-05-2011, 09:58 AM

Quote:

Originally Posted by Bud Cline

Appropriate thickness stock, appropriate thickness stock, h-m-m-m-m, I guess I don't know what appropriate thickness stock is.

Well I don't know the height difference right now but, e.g. if it is 2" I might use 2x4s. If the joists are hatcheted, I can also sister the new joists as you say up to height.