Garage addition / slab question

[Blue Seducer]

Ok guys, my 24 x 40 garage is full. I am planning to grab the back and stretch it 36' which will make it 24 x 76. The existing slab is post tension. Should I stick with that design for the addition or just go with rebar and wire. The new slab will be tied into the old with dowels.

 

[PAToyota]

Why is the existing slab post-tensioned? The design reasons behind it may apply to using it for the addition as well.

 

[Blue Seducer]

The original design was for a two story structure plus the weight of a 28' offshore powerboat with twin i/o chevy v8's carring 150 gals. of fuel. The boat & trailer package weight is about 10k lbs. I also have two cars in there as well. The new structure will be the same design as original. The house was built with post-tensioned slab as well.

 

[PAToyota]

Around here, post-tensioned concrete construction for residential (as well as most small commercial) is not the usual course of action - that is why I asked. I've designed commercial truck garages with standard tied rebar reinforcing.

Even with the loads you describe, unless there are certain soil bearing conditions that predicate it I would say that the post-tensioning is overkill and you could likely get away with normal reinforcing.

 

[Jaguar Fan]

Around here, post-tensioned concrete construction for residential (as well as most small commercial) is not the usual course of action - that is why I asked. I've designed commercial truck garages with standard tied rebar reinforcing.

Even with the loads you describe, unless there are certain soil bearing conditions that predicate it I would say that the post-tensioning is overkill and you could likely get away with normal reinforcing.

I was pretty surprised. In the Las Vegas area, even production tract houses in large developments are all post-tensioned, and you'd think they would go with the cheapest construction method. And, of course, they are all stamped with a warning "post-tensioned concrete. Do not cut, core, or drill". Even being post-tensioned, there are large control joints required based on typical residential loads.

 

[PAToyota]

Hmmm... Learn something new everyday...

To me, post-tensioned concrete is nearly always used in applications requiring the slab to span over something - either poor soil conditions in slab-on-grade or elevated slabs. Especially for slab-on-grade, a heck of a lot cheaper to just lay the rebar down and pour over it than go to the trouble of coming in with all the hydraulic equipment to tension the cables.

 

[Wardster]

We post-tension the hell out of precast (and even some cast-in-place) concrete when building bridges. PT on a residential slab is a first for me too, but I can see where it could be beneficial.

-Wardster