Post tension foundation?

[MFortie]

Curious about post tension construction...

I'm not really familiar with it (I do know WHAT it is) and am wondering if all things being equal, is it good?

I assume it's used where the soils dictate that type of construction?

Given two houses, same floorplan, etc. -- one being in an area that calls for post tension construction and one in an area that uses traditional reinforced concrete slabs, which one is preferable? (Everything else being equal.)

Thanks,

Mark

 

[nine4gmc]

In for info, we just bought a house with a post tension slab. Thanks for posting.

 

[8man]

Post tension is designed for the slab to "float" with the movement of the soils, if there is any. That means you will have cracks in the walls (inside and out) with a post tension if there is movement and they will tell you "it is designed to move like that."

Also think about it this way, the cables are laid and then they pour the concrete into the form. Concrete slurry is heavy and as it is poured in there is an opportunity for the force of the concrete to move the cables. Then when they pull the tension on the cables, if they aren't straight they will pull against not for the structure. If the cables aren't straight they can't do their job properly.

So all things equal I go with traditional reinforced slabs. In some areas I have to use piers drilled into the soil to reach a load bearing clay, but the houses don't move that way. In some areas I have to "beef" up the beams to provide the structural strength to hold the house without movement. This provides security against the movement of the soils.

The first house I built for myself had post tension and we had a crack in the front brick wall by the time we moved in. I swore I'd never do that to anyone again.

 

[HAY YOU]

If given a choice I'd go post tension. There is rebar still in the slab along with post tension cables which are in tubes. Every concrete story job or concrete bridge girder is post tensioned.

 

[404]

Keep an eye on the cable ends for post tension. Cable corrosion or end attachment failure are a problem. Post tension uses less material at higher stresses, costs less for the builder to do.

 

[SILVERPLATE]

I just completed a home in Texas that is post tension and piers. I have about 50 piers drilled anywhere from 3 feet to 15 feet deep, filled with rebar and concrete. The post tension slab sets on top.

 

[buzz4041]

Post tension is the norm in our area due to soil conditions. As long as it is properly tensioned you should not have any problems with it. We have a sprinkler system all around the foundation of the house also to keep the ground from shrinking in the summer which will also play havoc on a foundation. Many people that do not do this have foundation problems in our area.