Boring hole - missing post-tension, rebar

[sfav8r]

We need to drill a small hole (1") through a 10" slab. My concern is that I don't know if the floor is a post-tension slab or if there is other conduit in the slab. This is near an existing panel and I believe we have identified all the electrical conduit, but there could be other pipes, post-tension cables, rebar, etc.

It's a small hole, but I'm curious what other do in this situation. Like Client Eastwood says "Do you feel luck punk?"

I was thinking of jsut adding the the estimate that the building engineer must approve the boring location and let them figure it out, but I suspect if we hit something, that piece of paper may not be enough. They may say we should have x-rayed.

 

[brian john]

We need to drill a small hole (1") through a 10" slab. My concern is that I don't know if the floor is a post-tension slab or if there is other conduit in the slab. This is near an existing panel and I believe we have identified all the electrical conduit, but there could be other pipes, post-tension cables, rebar, etc.

It's a small hole, but I'm curious what other do in this situation. Like Client Eastwood says "Do you feel luck punk?"

I was thinking of jsut adding the the estimate that the building engineer must approve the boring location and let them figure it out, but I suspect if we hit something, that piece of paper may not be enough. They may say we should have x-rayed.

Can you say XRAY...sub it out add it in the estimate and spell out EXACTLY what you are doing cheaper than buying a building.

 

[infinity]

I've worked in buildings like that before and the building owner made x-rays of all penetrations mandatory. Not a bad idea IMO.

 

[ultramegabob]

What does it cost to have someone come out and X-Ray for a hole?

 

[cowboyjwc]

Well you could just drill the hole and if you hear a loud pop then you know it's post tension and if the bit gets stuck they it has rebar. :grin:

I would bet that at 10" thick there are a couple of layers of rebar.

Even if you found the plans they still wouldn't tell you where the steel or cables are. I vote x-ray also.

 

[LarryFine]

They may say we should have x-rayed.

I would say they should, or add the cost to the bill.

 

[chevyx92]

We need to drill a small hole (1") through a 10" slab. My concern is that I don't know if the floor is a post-tension slab or if there is other conduit in the slab. This is near an existing panel and I believe we have identified all the electrical conduit, but there could be other pipes, post-tension cables, rebar, etc.

It's a small hole, but I'm curious what other do in this situation. Like Client Eastwood says "Do you feel luck punk?"

I was thinking of jsut adding the the estimate that the building engineer must approve the boring location and let them figure it out, but I suspect if we hit something, that piece of paper may not be enough. They may say we should have x-rayed.

How do you know its a 10" slab, just curious.

 

[Cow]

Some things aren't worth the risk, just x-ray it and be done with it.

 

[ohmhead]

Well heres what happens when you hit a post tension cable it has 8000 to 12000 lbs of tension on it if it breaks it will fly out of the wedge cap like a bullet anything in its path is bad news .
This doesnt happening all the time some just break and stay put!

But when its 30 floors up it gets lots of attention from the construction team below !

Sometimes they break and can not come out of the slab thur there plastic tube they come out thur the slab rolling up and everything in that path is gone like chunks of concrete flying !

How do i know this twice in my life time on two jobs someone core drilled one and once someone chip one and cut it now just so you know you can repair a cut post tension cable if it just breaks and does not come out or you pay the money to push in a new cable .

Advise to go by take pictures of every electrical room during construction document it then if you need to drill most structual engineers will let you with out exrays.

 

[sfav8r]

I contacted a local x-ray company and the cost is quite reasonable, about $200. Not even worth thinking about. They can be here with 2-days notice.

Thanks for all the input.

chevyx92, you asked about the depth of the concrete. We were able to determine the depth because there is an existing conduit running through and we measured the wire then measure the conduit top and bottom.

 

[Sierrasparky]

Worth every penny!