Cutting concrete slab

[MiamiCuse]

I need to cut a trench in a 4" thick concrete slab for plumbing work, the trench needs to be 20" wide, and the trench runs along the direction of an exterior wall. However, the centerline of the trench is only 18" from the wall, so when the trench is cut, there will only be 8" of slab left on the side of the wall.

Is 8" enough of the slab to be left there? or should I just knock out the

8" and make the trench 28" wide?

When I am done with the work, and need to pour concrete to fill in the trench, I will need to drill rebars into the old concrete slab, will having

8" of slab on that one side help any?

If I knock that 8" out, will I drill the rebars into the 8" thick concrete block wall instead?

Thanks,

MC

[Caesar Romano]

On Thu, 3 Sep 2009 21:57:36 -0400, "MiamiCuse" wrote Re Cutting concrete slab:

Just make the trench 28" wide. It will make life a lot easier for you.

No. It will be a hinderance.

No, just connect to the slab.

[Jim Elbrecht]

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What Caesar said- plus, there's a good chance that the slab is just floating on the footer, anyway, so just make your cut 28" from the wall, whack a few times with a sledge and it should all lift out.

And when you cut it-- use a *wet* diamond blade. For the cost of renting a big saw you can buy a 7 1/4" diamond blade that you'll find real handy. As long as you don't cut a lot of rebar they seem to last forever. I have a 40 yr old Black and Decker 7 1/4 skil saw that I use.. The bearings were complaining when I relegated it to that position several years ago. They still squeal like pigs when the saw starts and stops--- but it keeps on keeping on.

A trickle of water from a hose provides the wetness and eliminates dust. [I plug it into a GFI extension cord- so far I haven't tripped it.]

Jim