Pre stressed concrete

[robinhood150]

How do I know if my house has a pre-stressed concrete foundation? I need to bolt down a safe to the floor. My house was built in 1998 here at Gilbert AZ and it's a typical tract home.

[Travis Waldher]

I would find it very unlikely.

http://en.wikipedia.org/wiki/Prestressed_concrete

prestressed and reinforced aren't the same thing. I won't say all homes, but almost every home will have a reinforced concrete foundation/pad.

[WIX]

Some house foundations are done by post tensioning. A way to tell is to look around the perimeter of foundation/slab for groups of 3"-4" holes filled in with grout. That would be the end of a cable. More than likely your house is just reinforced with rebar.

[robinhood150]

Yeah, I gathered it would be unlikely, but at least one person at work has it. I'm not sure what kind of house he has though and I heard they're more common with pre-fabbed homes. It would be nice to know for sure because once I drill through one of those tension cables it's too late.

[robinhood150]

Some house foundations are done by post tensioning. A way to tell is to look around the perimeter of foundation/slab for groups of 3"-4" holes filled in with grout. That would be the end of a cable. More than likely your house is just reinforced with rebar.

Would I need to dig down a little to see them or are they near the top?

[rokdog03]

I have done both conventional slabs and post tension. And if its post tension it should be stamped "DO NOT CUT OR CORE" in your garage flloor. Also the post tension slabs i have done are 7 inches thick and at the exterior walls their are turn downs where its a thicker, And usually the cables are centered.If its conventional foundation the footings and stems can vary in size based on soil conditions but the slab itself is usually only 4 inches thick. Even if you drilled thru a cable i wouldnt stress about it. And dont let people tell you that if you hit a cable its gonna explode thru the slab and hurt someone cause it wont.

[Chris]

Right, so clearly you've never seen a deck explode?It can FULLY happen, even with just ONE cable.
I had a guy lose most of his left hand due to ONE cable at 25k psi come out of the slab. :shaking::shaking:

With more it's even worse, I had a section of 20 banded cables straighten out once and it took the concrete out in a section 10'x20' and it was a 14" deck. We found pieces of concrete 500 feet away from the explosion.

[rokdog03]

Well all the houses i have built in az have been stressed to 3500lbs to 4500lbs. And i am on a apartment job right now that we are replacing 41 cables due to the framer hitting them when drilling for red heads and chemical anchors. Also the plumber has hit quite a few chipping up the floor and not one explosion. Maybe im just lucky.Who knows.

[bgaidan]

Cables in a residential slab vs. something in a structural deck (bridge?) are significantly different. A cable tensioned to 3k-4k isn't going to explode.

[Chris]

Cables in a residential slab vs. something in a structural deck (bridge?) are significantly different. A cable tensioned to 3k-4k isn't going to explode.
The first example I mentioned was in a house slab. It can happen, period.