Concrete Cutting for Shower Drain


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Old 06-03-06, 12:10 PM
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Concrete Cutting for Shower Drain

I had a previous thread asking for a price guesstimate of installing a shower in a slab construction. Well I got the bids back and they seem outragous. I'm also a contract and I charge nowhere nearly what they do for there hourly rates for contract work and not time and material. They ranged from 2.5k to 2.9k for 8 hours of claimed work to cut a 2x2' of concrete away and tie onto a 4" cast like with a trap and come up and put a drain stubbed out of the floor for a shower. The contract was only to set the drain pipe and shower pan, no hot or cold lines..etc. Now on to the new question.

I've done quiet a bit of research and feel compentent enough to tackle the tieing into the cast line and doing the normal pvc shower trap stub up. My question relates to cutting the slab, its 4" thick. I've got access to a saw and a electric jack hammer. Would I saw all the way through two foot on each side of the area I need open, then score across with the saw twice and break it into 1x1 blocks with the jack hammer? Also what are the dangers with using this saw kickback etc...? I'm looking for tips from anyone whos cut a slab before, so I don't make mistakes with this. My wifes approach is I can do the work for $200 roughly, hecks its worth the attempt worst that can happen is theres already a hole cut and I pay less to a plumber.

Also when I fill it back in would I drill holes in the sides of the slab and slide rebar into the old and tie it in with the new pour?

Thank you,

Roy
 
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Old 06-03-06, 12:36 PM
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What kind of saw are you thinking of?

Partner saw, wheeled floor saw, electric, gas?

if you use a gas powered, VENTILATION!

with all saws, eye protection. ear protection would be good too. I haven't had any problems with kick back with the partner saw. It pulls away from you and because you are using an abrasive blade, there are no teeth to grab and kick it. Not saying it can't happen. just never had a problem with it myself. Just keep good control and unless you a a very small guy, you should be able to handle it.

If you can use water, do it. It will save the blade (some saws require it) and it helps keep the dust down. Be careful as to where the water goes though.

Your ideas sound sound. Try to avoid cutting into whatever is below the concrete. If it is dirt, it will dull the saw blade.

Actually I don't think the jack hammer would be neccessary if you cut well. Just cut it as you laid out, get a big pry bar, pry up the slab and use a sledge to break the cut out it you did not get it all the way cut through.
Make your cuts as vertical as possible. If you undercut the remaining slab, it will make it difficult to remove the cut out.

Make sure there is nothing in the slab that you might cut.

Seal the room as best you can, including any HVAC vents to avoid dust getting into them and subsequently throughout the house.

The rebar idea, good idea.
 
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Old 06-03-06, 01:46 PM
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Thanks for the tips Nap.

It would be a partner saw gas powered. I was going to seal off that section of the house with 6 mil poly, and the ducts. Open the back door and stick a box fan sucking in, and open the slider sticking a box fan sucking out, It would turn the place into a wind tunnel. I was going to have my friend spray the area with a mist from the hose and run the wet dry vac.
 
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Old 06-11-06, 10:50 PM
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I think that you may need a hammer, as I would hope that there's some rebar in the slab. The less rebar you cut, the better. If you find that you do have to cut some rebar, you should drill horizontal holes in the slab and epoxy some rebar back in.

Now that I think about it, why use a saw at all? You can patch the jagged concrete opening, and you'll probably have a subfloor over it, with vinyl or tile on top of that.
 
 

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