Job 03 — Garage & shop slabs
Garage & shop slabs, built for the load
Section 01 — Why garage & shop slabs are different
A garage or shop floor carries more than a patio ever will — vehicles, jacks, tool chests, sometimes a lift. The spec that's fine for a walkway will crack under that kind of point-loading. Here's what a garage or shop slab actually needs and what it costs.
What it costs
| Job | Spec | Typical $/sq ft |
|---|---|---|
| Attached 2-car garage slab | 4–5" · mesh or rebar | $5 – $9 |
| Detached garage or pole barn floor | 5" · rebar · 3,500 PSI | $6 – $10 |
| Shop floor with equipment / lift loads | 6"+ · rebar · 4,000 PSI | $7 – $12 |
A typical 24×24 (576 sq ft) two-car garage slab lands around $3,000–$5,200 depending on thickness and site prep. Detached shops with heavier equipment plans run higher per foot for the extra rebar and PSI.
Section 02 — The spec that actually matters
What a garage or shop slab needs
- Vapor barrier under the slab. Non-negotiable for a garage or shop — without it, moisture wicks up through the concrete and shows up as flooring failures, rust, or a permanent damp smell years later.
- Thickness matched to the load. 4" is the floor for a light-duty garage; 5–6" with rebar is the right call if you're planning a lift, heavy equipment, or a loaded truck parked inside.
- Reinforcement. Wire mesh is standard for light-duty garages. Rebar on a grid is the upgrade for shop floors — it's what keeps a crack from becoming a step.
- Control joints planned before the pour, not cut wherever's convenient after. A shop floor with joints in the wrong spot will crack somewhere you didn't want it to.
Worth knowing
If you're planning a car lift, tell the contractor before the pour, not after. Lift anchor points need a thicker slab section and sometimes a reinforced pad poured specifically under those posts — retrofitting that into an existing slab is expensive and sometimes not possible at all.
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