Concrete guys - Post-tension?

[vectorit]

Question for you concrete guys...

I needed to have something installed in my garage, and the installer needs to anchor it to the floor by drilling down through the slab to install bolts.

He asked "Do you know if the slab is post-tension"?

I have seen the stamps in floors before, warning that the slab was post tension. But in my case being residential, I can not find a stamp in the concrete indicating if it is a post-tension slab.

The installer told me that there is builders in my area, that did do slabs as post-tension but he couldn't tell me all of the builders names.

My house was built in 2001, and from what I have learned so far that right at that year builders starting doing post-tension in my area.

So... If a builder was to do post-tension, are they required to stamp the warning in plain view? like at the threshold of the door way or something?

Is there a way to tell a post-tension slab by looking at some tell tale signs on the borders or something?

[pritch]

Originally Posted by vectorit

Is there a way to tell a post-tension slab by looking at some tell tale signs on the borders or something?

Yes, but...you would have to expose the outside of your foundation from the level of the top of the slab down at least 6 or 8 inches. You should be able to see a series of patches where the contractor would have grouted over the anchors. Hard to say how often they would be, every 4 feet or so would be fairly common. You definatly don't want to cut into one as the tendons have thousands of pounds of tension on them.

[Fitz]

Originally Posted by vectorit

Question for you concrete guys...

I needed to have something installed in my garage, and the installer needs to anchor it to the floor by drilling down through the slab to install bolts.

He asked "Do you know if the slab is post-tension"?

I have seen the stamps in floors before, warning that the slab was post tension. But in my case being residential, I can not find a stamp in the concrete indicating if it is a post-tension slab.

The installer told me that there is builders in my area, that did do slabs as post-tension but he couldn't tell me all of the builders names.

My house was built in 2001, and from what I have learned so far that right at that year builders starting doing post-tension in my area.

So... If a builder was to do post-tension, are they required to stamp the warning in plain view? like at the threshold of the door way or something?

Is there a way to tell a post-tension slab by looking at some tell tale signs on the borders or something?

In most states where soil conditions warrant the use of post tension slabs the building codes require the builder to cast the words "Post Tension" right into the slab at the perimeter of the "most commonly used" opening. In my case, the main garage door opening. Any relatively cheap stud finder (read as SEARS) will determine if your slab is post tension or not. Lay a reference edge (2 by four) on the floor perpendicular to the exterior wall and move it along the edge. Here in Arizona the spacing of the cables is 12 inches OC. If you don't find any, rotate the straight edge 90 degrees and do it again. Studfinders are actually magnetic sensors and work by sensing the small magnetic field changes caused by the nails used to attach drywall. They will not miss the steel cables used to tension a slab.

If that still doesn't indicate any cables the slab isn't likely to be a post tension slab.