Audie Tarpley has built a lot of parking garages. One of the standout projects from his Dillon Construction Group portfolio is a 300-car cast-in-place structure in the Indianapolis area — and it’s a good illustration of why the method you choose matters more than most people realize.
There are two main types of concrete parking garages. Precast and cast-in-place. They’re not interchangeable, and the differences go well beyond construction speed.
Cast-in-place: built on-site, built to last
With cast-in-place construction, everything happens at the job site. Concrete gets poured directly into forms, which are removed once it sets. The structure is reinforced through mild steel or post-tensioning — more on that in a moment.
What Audie Tarpley’s team gets from this approach is durability. Real durability. Because slabs and beams are poured together on-site, there are far fewer mechanical connections and joints than you’d find in a precast garage. Fewer joints means fewer places for water to sneak in. Fewer leakage points means less corrosion, less deterioration, and lower lifecycle costs down the road — no endless rounds of caulk sealant applied to hundreds of joints.
The design flexibility is another big one. Formwork can be adjusted on-site, which opens the door to custom features: elevated clearances, wider turning radiuses between levels, more open layouts. Beams and columns in cast-in-place structures handle serious load, so you’re not cramming in extra walls. Beams run 20 to 24 feet apart. Compare that to precast tee stems, spaced every five or six feet. The result is a more open, lighter-feeling structure — better for drivers, better for visibility.
Precast: faster, but different trade-offs
Precast concrete has its place. When speed is the priority, it’s hard to argue against it. Think of it like snapping together large prefabricated components — walls, beams, columns — manufactured offsite in a climate-controlled facility, then assembled on-site. The most common wet-cast method pours concrete into a mold, vibrates it to remove air pockets, and removes it once hardened.
Pre-stressing adds another layer of strength. High-strength steel wires get inserted into a beam, stretched, anchored, then encased in concrete as it hardens. Once the strands are cut and the formwork stripped away, you’re left with a component that resists cracking under external load — moving vehicles, temperature shifts, the usual suspects. Lighter structures, shallower profiles, solid strength.
Post-tensioning: the cast-in-place advantage
Here’s where it gets interesting for cast-in-place work specifically. Post-tensioning involves high-strength steel cables — tendons — that are tensioned after the concrete hardens. These cables run in a crisscross pattern, continuously compressing the slab across its entire lifespan. The result: higher load capacity, fewer cracks, and genuinely superior watertightness from the slab’s bi-axial compression. De-icing chemicals, standing water, road grime — less of it gets through.
Maintenance: neither type gets a free pass
That said, no concrete parking structure runs itself. Both precast and cast-in-place garages need consistent preventive maintenance. The tricky part? Deterioration often starts below the surface, invisible until it’s already become a problem. Active monitoring — regularly, not reactively — is the only way to catch structural issues, cracks, leaks, and rust before they turn expensive.
Audie Tarpley’s work on the Indianapolis garage reflects this thinking. The method matters. So does the long view.
