How Long Does It Take to Pour a Concrete Slab?

Quick Answer

Pouring a concrete slab takes 1–2 days for the active work (site prep, forming, pouring, and finishing), plus 28 days for full curing. The concrete is strong enough to walk on after 24–48 hours and can bear moderate loads after 7 days, but reaches its full rated strength at 28 days.

Timeline by Slab Size

Slab Size	Purpose	Prep Time	Pour Time	Total Active Work
4×4 ft	Small pad	2–3 hours	1–2 hours	Half a day
10×10 ft	Shed base	3–5 hours	2–3 hours	1 day
12×20 ft	Patio	4–6 hours	3–4 hours	1–1.5 days
20×20 ft	Garage (1-car)	6–8 hours	4–6 hours	1.5–2 days
24×24 ft	Garage (2-car)	8–12 hours	5–8 hours	2–3 days
30×40 ft	Workshop	1–2 days	6–10 hours	2–3 days

Concrete Curing Timeline

Milestone	Time After Pour	Strength Achieved
Initial set	2–4 hours	Surface firm
Walk-on ready	24–48 hours	~15–20%
Light loads	7 days	~65–70%
Vehicle traffic	10–14 days	~80–85%
Full rated strength	28 days	100%
Maximum hardness	60–90 days	100%+

Step-by-Step Process and Timing

Day Before or Morning Of

Site preparation takes 2–6 hours depending on conditions. Excavate to a depth of 8–12 inches below the desired finished grade, removing any organic material. Compact the subgrade with a plate compactor. Add 4–6 inches of compacted gravel base.

Forming takes 2–4 hours for a standard rectangular slab. Use 2×4 or 2×6 lumber staked every 3–4 feet. The forms must be level and set to the correct elevation with a slight slope (1/8 inch per foot) for drainage. Install rebar or wire mesh reinforcement on chairs to position it at mid-slab height.

Pour Day

The pour itself is the fastest part of the project but demands the most coordination. A ready-mix truck delivers concrete at roughly 1 cubic yard per minute. A 20×20-foot slab at 4 inches thick requires approximately 5 cubic yards, which can be poured in under 10 minutes from the truck.

Screeding and floating begin immediately after the pour. Screed the wet concrete level with the forms using a straight 2×4, then bull-float the surface to push down aggregate and bring cream to the surface. This takes 30–60 minutes for a standard patio-sized slab.

Finishing includes edging, jointing, and final troweling or brooming. Control joints should be cut at intervals no greater than 2–3 times the slab thickness in feet (e.g., every 8–12 feet for a 4-inch slab). Total finishing time is 1–3 hours, depending on the desired surface texture.

Factors That Affect Project Time

Weather is critical. Concrete should not be poured when temperatures are below 40°F or above 90°F without special precautions. Hot weather accelerates setting time, giving less time to finish the surface. Cold weather slows curing and may require insulating blankets.

Access for the concrete truck can complicate delivery. If the truck cannot back up to the pour site, a concrete pump ($200–$500) or wheelbarrow relay is needed, adding 1–3 hours.

Permits and inspections may be required for slabs over a certain size or for attached structures. Permit processing takes 1–4 weeks, and an inspection of the forms and reinforcement before the pour may be required.

Mixing on-site with bags is feasible only for very small slabs. Mixing an 80-pound bag yields 0.6 cubic feet — a 10×10-foot slab at 4 inches requires over 50 bags and 4–6 hours of mixing alone.

DIY vs. Professional

Factor	DIY	Professional
Prep and forming	4–8 hours	3–5 hours
Pour and finish	3–6 hours	2–4 hours
Cost (10×10 slab)	$300–$600	$800–$1,500
Skill level	Moderate–High	Expert
Risk of errors	Higher	Lower

Concrete is unforgiving — once poured, there is a narrow window to get the finish right before the surface sets. For slabs larger than 100 square feet, hiring a professional crew is recommended unless the builder has prior experience.