Running into metal while drilling concrete

More over and drill another hole, easy enough to fill the old hole.

Bad Dog bit: http://www.baddogtools.com/videos2.html

http://www.baddogtools.com/multi-purpose-drill-bits.html

Make ABSOLUTELY certain you do not have a prestressed or post tensioned concrete slab. In either case, the steel strands can explode if you cut through them with a drill bit.

Post tension slabs aren't that common in residential. They would also see that the cable is in an enclosed housing and wouldn't have concrete around the cable itself. It would also look like a cable not solid rod of metal. Seems like they are hitting rebar and not a pre-stressed tendon.

Chitown, I am curious what your basis is to conclude that the OPS likely ran into rebar. The OPS makes no observations about what he ran into, only that he thinks it was metal. He also states the slab was 4 inches thick. I have examined dozens of houses built down south with post tensioned or prestressed slabs, very common in expansive clay country. Not so common in Pennsylvania, as you note, but certainly possible. My experience with normal reinforced 4 inch slabs is that there is typically welded wire fabric reinforcement rather than steel bars. I was simply trying to warn the OPS about the potential for hitting stressed tendons, if you cut them it is an experience you will probably regret.

Daniel Holzman said:

Chitown, I am curious what your basis is to conclude that the OPS likely ran into rebar. The OPS makes no observations about what he ran into, only that he thinks it was metal. He also states the slab was 4 inches thick. I have examined dozens of houses built down south with post tensioned or prestressed slabs, very common in expansive clay country. Not so common in Pennsylvania, as you note, but certainly possible. My experience with normal reinforced 4 inch slabs is that there is typically welded wire fabric reinforcement rather than steel bars. I was simply trying to warn the OPS about the potential for hitting stressed tendons, if you cut them it is an experience you will probably regret.

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You already listed some reasons. It's only 4" thick, which is a bit on the thin side for a post tension slab (usually greater than 6"). He didn't hit the sheathing, which is larger than a metal cable and not metal itself. His area of the country. So there were a lot of reasons I doubt he's hitting a cable from a post tension system. Oh, and that's another, he said rebar and not cable.

I also think that saying it's "very common" is a bit of a stretch. It's becoming more common, but I wouldn't personally use the term "very common".

As for using the term rebar, I was just mirroring what he said, instead of saying it was wire from a mesh, it's what he referred to it as and I saw no harm in continuing the vernacular.

I guess I would have also expected more help when cautioning someone concerning something that they obviously don't know much about. You told him to be careful and make sure, but didn't follow up with how to be careful and how to make sure.

it should be stamped

mj12 said:

it should be stamped

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You should be able to see the cable caps or ends around the perimeter.