Securing a power rack on post tensioned concrete

[Satch12879]

These days, its quite common in certain areas. Where I'm at, almost every single tract house (large tract developments, bigger home builders, etc) is done this way.
For about 10-15 years now really (to a lesser degree when it first started).

And yes, its kind of fucky, because your slab will sorta drop down into the garage area, and then the garage has a bit of slope .... the cables will actually go thru all that area. You can imagine the cables dipping down and what not to stay in the center of the slab. A lot of weird unpredictable forces when the cables are tensioned later.
The form work gets tricky to pour a monolithic slab with the different floor elevations, and to let the cables go where they need to. Its fucking crazy if you ask me.

I would be super leery about dropping (or even so called "controlled lowering") of deadlifts with iron plates in the garage or any part of the building.

I would build one of those platforms with the recessed wells full of discarded carpet, etc. for the plates to bounce on.

I'll take your word for it, because it sounds wild and unnecessary, you know unless like Rip said, you're building on garbage soil. Still, we put garage slabs on coastal sand where you otherwise have to drive piles to support the house. My big issue with this is why the garage slab is intended to be continuous with the building in the first place. The way we usually do them, even with concrete structures, which are done, is the garage slab is just a simple slab-on-grade, which are always non-structural. Meaning while you definitely put loads on top of them, they're not carrying building loads. You pour the perimeter garage foundation, place or cast your stem wall above it, and then just float the slab inside its perimeter.

I would love to see the slab section and the details for the transition between the floor slab and the garage slab. If I'm understanding your correctly, the designer/builder is continuing the tendons effectively around a corner, really two corners, and hoping to provide enough tension to do what's intended.

Post-tensioning is still generally specialized work. The design of the system needs not more than a fair amount of experience; I did two semesters on it in graduate school, plus some additional work on the detailing of the anchorage design in other classes, i.e., strut and tie models. Seems to be overkill, honestly. I don't think I'd trust tract home builders to go anywhere near it.

[EdTice]

I don't have post-tensioned concrete but I wanted to protect my garage floor nonetheless. I used two sheets of 4'x8' 3/4" OSB laid side by side horizontally. Then an additional two sheets vertically. Then right in the middle of that stack, I used a 4'x8' sheet of maple 3/4" plywood. I then cut 2'x4' sections of maple and ran them along the sides closest to the rack. I bolted 1 inch lag bolts through the hardwoods (and I guess a little bit into the OSB). As my squat approaches 500, that damn thing has shown zero signs of moving AT ALL. Also of note: I'm in the deep south where humidity is brutal. I put a moisture barrier on the concrete beneath the OSB particle board and it has shown zero signs of warping. I do have a two degree slope on the garage floor that I could actually feel with my deadlift. One side of the bar always broke ground before the other. I shimmed it and haven't had a problem since. This was all done during COVID when plywood shot through the roof so the OSB saved me a little money.

Whether you have post-tensioned concrete or not (a term I never knew until this thread), many garages have plumbing underneath. Protecting the floor and protecting the plumbing are two sides of the same coin. Nobody wants to have to repair a supply or sewer line underneath their garage floor.

Hello everyone. First time caller, long time listener. I've finally gotten around to convincing the missus that not only do I need a power rack in the garage, I need one as soon as possible, because the gym is about to become a zoo with all the post-holiday repenters taking up already sparse rack space.

I however have one problem. All of the concrete in my house is post-tensioned. So, naturally, I can't drill into it to sink some lag bolts or something to secure the power rack.

I am looking for ideas. Right now I am thinking that a good 500 lbs of weights or so on the rack itself should do well to give it enough inertia that I can safely re-rack or drop weight onto the safeties. I am mostly concerned about tipping backwards on a bad/failed squat and knocking the rack over. Though, I'm not convinced this can even be avoided with bolts because the bolt holes I've seen on these racks arent big enough for substantial hardware anyway.

Are you trying to secure a full rack or a half-rack? We've had many discussions in the gyms/equipment forums about this. Many manufacturers make platforms that (they claim) don't need to be secured to the floor. The rack moving a bit isn't really a concern. Decent racks don't just spontaneously fall over. However, if one leg moves more than the other, they can get out of square to a point where the rack isn't really safe anymore.

I have relatively lightweight rack (Fringe Sport Garage Series) that I bought used during the pandemic when things were slim pickings. It sits on a platform and has weight storage posts where I've put about 300lbs. It hasn't moved any measurable amount in the past two years. Securing the rack isn't to prevent it from *moving* it's to keep it square. Even attaching one to a wooden platform is enough.