Foundation

Michigan Mike has a new project:

In preparation for building my pavilion/guesthouse/poolhouse/folly, I was investigating this "post-tensioned" concrete method and came across this:

Installing Post Tension Foundation

I don't know where to begin with what is wrong with all this except for the tensioning part.

• 16,000 square foot house on a monolithic slab.
• All buried utilities.
• 20 years max before this requires major surgery.
• Cracks big enough for termites will form by then, so another 10 years until structural failure.

Or am I wrong?
Should all housing be considered disposable, until we finally start building everything out of dry stacked cut stone like European cathedrals?

I quibbled:

As for what's wrong with this project, the first thing that hit me was the 16,000 square feet. I suppose if you are a frustrated empire builder you could devote your empire building energies to this house. Something like this would require a sizable full time staff just to keep it clean and in good repair. "Deploy maid squad #1 to the East wing, send the gardeners around to Southeast corner, get the maintenance squad to the home theater ASAP."

Most houses in Texas were built on post tensioned slabs. They were not as elaborate as this, no piers to bedrock, no cast-in-place beams, just a flat slab laid on the dirt. Of course most of them were more like 2,000 square feet (if you count the garage).

You are right about the major surgery, but it will be due to the whims of the owners rather than any weakness in the structure. Thinking you know exactly where you will want the outlet in the living room for the next umpteen years is a bit foolhardy. The slab itself will be structurally sound for 500 years.

As for termites, they are ubiquitous. This house would be no more or less susceptible than any other.

 Update February 2017 replaced missing video with something that I hope is similar. While this video shows work being done on a large house, it is not 16,000 square feet.