We built in central Texas, foundation problems are a big issue here. We have not heard a single good thing about the tension cables. I have heard of the cables breaking when being pulled. Our builder did not recommend them. Said he used them twice and did not like them at all. I can not remember off hand what it was he did not like about them.

We went with rebar in our slab. I could not tell you the psi off hand, I am sure DH knows. The vapor barrier, I will have to ask about that as well. I remember thick black plastic if that helps any :-)

I am not much help, I am sorry!! I do know that we got more no's then yes on the tension cables. Could just be the folks we talked to.

Good luck and I am sure you will receive some wonderful info from other folks here!

I'm in the same area. The type of slab you use will depend on your soil. The soil will be tested and the report will be used by an engineering company which will recommend a slab based on your soil on your lot. I would have thought that a builder would have gone over this process with you.

Yes, get a geotech survey done and an engineer to design your foundation. My municipality requires an engineer's stamp on the foundation design. We are in Central TX also and have clay mixed in with solid limestone. Our foundation is full steel rebar. There are many here that argue for post tension and I don't know enough about it except to say that all the spec home builders in the area use post tension and the custom builders use rebar. To me, that says post tension is cheap and easy. Which isn't to say it's inferior . . .

Anyway, our concrete is 4000psi and we have stained concrete floors. I believe it would have been 3500psi had we used some other floor material. The vapor barrier is polyethylene, which is the thick black plastic stuff.

Yes, you do need to get your soil tested but it may turn out that either foundation will be suitable for your location. We are in Magnolia. We had a choice and had our slab engineered for a conventional slab, not post tension. The post tension would have been cheaper but my husband felt more comfortable with a conventional foundation. That being said, I have been told it's not the slab that fails, it's the dirt. I can tell you we spent a pretty penny bring dirt in too. If you have a solid foundation under your foundation either one will last.

Thanks to all. I really appreciate the insights. One of the builders that I am talking with is proposing using both rebar and post tension. However, I've heard similar stories about the post tension cables breaking. They also want to go with just a 3000 psi concrete.

We will be talking to other builders.

3000 psi concrete would be fine for the house slab as long as it is fiber re-inforced. Exterior projects such as driveways,patios,rv parking should be 5ooo psi not fiber re-inforced as non fibered finishes smooth whereas fibered does not finish well. Any areas that are to be concrete only floors would be non fibered as well.

We used a post tension slab with our custom builder. It sits on concrete pilings drilled to 15 ft or bedrock, whichever came first. It is a 3-level slab in a sloping yard.

Post tension is not "cheap and easy" if it's done correctly. There's just as many "cheap and easy" rebar slabs around that are poured on 10 feet of new fill, no pilings, that's been "tractor compacted" and people will wonder why their home is doing the hula in 3 years time in Texas clay.

dallasbill, I'm in Central TX and HERE it is cheap and easy. We hit bedrock at about 2-3 feet.

If post tension is so inferior and cheap, grab the popcorn and watch the high end high rise condos in Dallas collapse.
The concrete floors in the Azure, the W, the House by Stark etc. as well as many concrete parking garages are built using post tension slabs.

Post tension is rather high-tech (compared to simple rebar). If done correctly, it is an excellent method.

And another thing is that it doesn't really matter what method you use. Your house will do the "hula" if your pilings/footings are not engineered correctly.

I live in a neighborhood where there is a lot of res. construction - half custom and half spec. All the custom homes are getting steel rebar foundations and it takes a week to finish. All the spec houses are getting post tension and it takes about a day to finish. It's the tension that makes the method work and I see a lot of potential for the tension failing. And guess what? No tension inspections required. I'm not bashing PT, it's just not my cup of tea. Well, maybe I am a little . . .

residential and commercial construction are very very different animals.

We are building Northeast Houston. I received the soil test back yesterday and the engineer recommended piers. I would go with the recommendation of the engineer.

You should like others have said go with what your engineer recommends.

Also a note on the cheap part. In an area with non-expansive soil a regular re-bar/mesh concrete foundation would in many cases be much cheaper. If you have expansive soil then the post-tension becomes cheaper due to less "work" needed to accomplish the same structural integrity. It isn't that one is cheaper as in getting an inferior product, but rather one is cheaper to do for that particular soil condition.

In an area outside reno, nv a developer had the choice of either excavating an average 3 feet of clay type soils and replace with the proper fill or go post tension. On a projected 400 house tract, the post tension was a no brainer.

lyfia... very well said!

No matter what type of foundation you use, the compaction of the soil is key. Even the most expensive pier foundations have failed due to poor pad compaction. Follow the engineer's recommendations for the design and construction of your foundation. Also, pay close attention to the pad site prep instructions you should also receive in the report. The fill should not be placed in quantities greater than 6" lifts and each layer should be thoroughly compacted prior to the placement of the next layer. There are engineering professionals available that test the fill compaction levels as well. The engineer who designed the foundation should make an inspection and sign off prior to the placement of the concrete. As long as you have your foundation engineered, and the guidelines are followed, you have a much better chance of your foundation surviving than the person who just used a certain type of foundation because "that's what he's been doing for 30 years".