Post tension cable slab for garage

[bradpac]

I'm in the process of getting bids to build a probably stick built 30x30 detached garage in central Texas. Still looking for the right guy, if anyone can send me a name that would be great.

But my question, I have gotten one bid back that mentions using post tension cables in the foundation for the garage. We are east of Austin on highly expansive black clay soil and our house does have this foundation construction, but I have never heard of it used in a garage and wanted to get opinions on if it was necessary or if it might be a detriment for mounting things later on down the road. I would think as long as I mark the cable locations and don't hit one it should be fine.

 

[My Old Tools]

I have been on black clay soil as well. Post tension is used in homes, but in my experience, larger grade beams and larger and more rebar is just as effective.

 

[Zmann]

as long as you mark the locations you should be fine

 

[K'ledgeBldr]

For a 30X30 garage I think PTC is overboard.

I'd go the route of MOT's suggestion- larger grade beams, and larger rebar.

 

[nadogail]

Some of my rental houses in Chula Vista, CA have post tension slabs as garage floors, they are marked with a DO NOT CUT OR DRILL warning.

These were built before I bought them; had I a choice I would have preferred conventional rebar and larger grade beams.

 

[Git]

Our entire house in S Cal has a post tension cable slab and I have bolted some smaller things to the garage slab. Keep in mind that the cables are run in a 'conduit'. Since I don't know where the cables are, I drill a fairly small hole first and I check to see if I can see the conduit or if I suddenly have pvc remnants coming up out of the hole, it would be time to stop

Personally, I can't see how your typical concrete drill bit could actually cut into the steel cable to begin with - if you were using a coring bit, that would be a different story...

 

[bradpac]

This same guy says his usual spec is 36" deep beams 12ft on center, plus post tension. Probably why he's more than I can afford.

 

[Retroman]

Not really a conduit but a plastic sleeve that is greased inside to facilitate the tensioning of the cables. I am in the cutting and coring business and have cut and cored thru many of these cables I can tell you it only takes one strand to be cut and then the rest of that cable lets go. Have never damaged one with a Roto-Hammer when drilling to set anchors. My house and attached garage have cables and the garage is not stamped.

 

[zeke67]

The main point for the OP, if you are going to put a lift or anything else you plan to bolt down, make sure you have them mark where the cables are, keep a copy of the plans, or take pictures. For sure if you are a planning a lift right away, you need to dusucss ahead of time where you want to put it.

 

[Git]

Not really a conduit but a plastic sleeve that is greased inside to facilitate the tensioning of the cables. I am in the cutting and coring business and have cut and cored thru many of these cables I can tell you it only takes one strand to be cut and then the rest of that cable lets go. Have never damaged one with a Roto-Hammer when drilling to set anchors. My house and attached garage have cables and the garage is not stamped.

That is good to know - thanks

Would you agree that it would be pretty hard to damage one of the cables with your typical cheapo type masonry bit or not?

 

[Retroman]

That is good to know - thanks

Would you agree that it would be pretty hard to damage one of the cables with your typical cheapo type masonry bit or not?

Yes that is the type of bit I used to drill the hole for the anchor to bolt down the core drill. Bit just stops like your hitting rebar and does not damage the cable other than a hole in the sleeve which I guess could eventually cause the cable to rust. I suppose if you kept after it long enough it may damage the cable but if you stop when the bit stops advancing in the hole your fine but Diamond bits, blades and and air jack hammers will take them out right quick.

 

[Git]

Yes that is the type of bit I used to drill the hole for the anchor to bolt down the core drill. Bit just stops like your hitting rebar and does not damage the cable other than a hole in the sleeve which I guess could eventually cause the cable to rust. I suppose if you kept after it long enough it may damage the cable but if you stop when the bit stops advancing in the hole your fine but Diamond bits, blades and and air jack hammers will take them out right quick.

thanks

 

[nyy845]

Just an FYI, you can also locate PT cables with GPR (Ground Penetrating Radar).