Post tension slab labeling

Aren’t post tension slabs suppose to be labeled? Is the labeling usually put into the garage slab floor?

On the garage foundation there is a stamp that says “Post tension slab, do not cut or core”. Yes. There are machines that will find the cable and their placement. Residential is rare but is used in Texas. We have them in our jail that I helped construct. I watched it being done.

Not rare at all in residential, in fact, it’s very common.

The warning requirement only applies to residential. It is not required in commercial applications.

In residential, the slab should be stamped. Generally it’s done in the garage so that it remains visible. If there is no stamp, there must be a permanent sign posted.

Really. I read it was rare. What states?

It is common here in Arizona. i will attach a few pictures.

I was placing cables in residential foundations in the '80’s. Almost every home built in the last decade or so in CA has a PT slab/foundation.

I think it’s pretty popular in TX as well.

Here is the stamp.

I have yet to find one here in Silver, have you found some in Cruces?

If the slab is PT and there is no warning mark, it should be called out. Once the sidewalks are poured and ground cover is placed, it can be difficult to determine if cables are present.

While I am talking to the structure experts let me ask this. What determines where they put the siding on the vertical walls. I watch a lot of homes being built and I can find no rhyme or reason to where the chip board is added and where it isn’t. I would like to see a set of plans that the framers use but so far I haven’t had the chance.

Generally, it has to do with the required shear-strength (the design strength) of the wall. Sometimes it’s paneling (as you have pictured), and other times it will be steel panels or “strong-walls.”



I haven’t seen the steel. Is it common to see some walls with no panels? Here in AZ I have seen the same model, one house facing north and the other facing south with the chip board on different walls. Prevailing winds???

Possibly. It’s all a matter of “design criteria” in your area. Most of CA is in SDC 1 and SDC 2 (Seismic Design Category), so these steel panels are common. AZ’s designs are (I’m sure) different from ours.

Where the wall dimensions limit the amount of lumber that can be used to obtain the required strength, these strong walls are the substitute.

I will try to find pics of the ones at the jail

Here ya go. Orange County Florida Jail

Post Tension Cables in Slab 1.jpg

Post tension slab is the foundation of choice around Texas with the exception of few enclaves and the older homes.

I haven’t seen a stamp, label, certificate…onsite in over seven years, this is my 10th year inspecting and have been watching or building residential and commercial since the mid sixties.

Not to argue or disagee with others but this “must” be a regional thing or they ignore it around here.


Do you have a reference citing for, “If there is no stamp, there must be a permanent sign posted.”

It is stamped here in AZ and a tag is also on the main water valve shut off.

The Post Tensioning Institute (PTI) is the “authority” with regards to PT. It is their recommendation, but I’m not sure how it is mandated.

I agree with Barry, lots of PT slabs around here but I have never seen the stamp or sign nor do I write up the lack of one. It makes sense though and I may start recommending the labeling.


Thanks fo the reply