A concrete patio transforms your backyard into an outdoor living space—but getting it right requires understanding the installation process, timeline, and what separates quality work from costly mistakes. Most homeowners spend $1,500 to $5,000 on a 12×16 patio, depending on finishes and site conditions, and the process takes 1–2 weeks from excavation to cure. Knowing what happens at each stage helps you manage expectations and spot red flags when hiring contractors.
Site Preparation and Planning
Before a single bag of concrete touches the ground, the contractor must assess your yard and plan the layout. This includes marking the patio dimensions, checking for slope (essential for water drainage), and identifying any underground utilities like gas lines or irrigation. Most patios slope slightly—typically ¼ inch per foot—to shed water away from your home.
The contractor will also evaluate soil conditions. If your yard has clay, poor drainage, or unstable ground, you may need a compacted gravel base (usually 4–6 inches deep) to prevent cracking and settling later. This step isn't glamorous, but skipping it or doing it poorly is the leading cause of patio failure.
Excavation and Base Work
Once planning is done, the site gets excavated to the correct depth. For a standard patio with a 4-inch concrete slab and 4-inch gravel base, you're digging about 8 inches down. The contractor will remove existing grass, topsoil, and debris, then grade the subbase so it's level and compact it firmly.
Quality contractors use a plate compactor or hand tamper on the gravel layer—this prevents settling that could crack your finished patio years down the line. Expect this phase to take 1–3 days depending on patio size and site accessibility.
Formwork and Layout
Before pouring, the crew sets up wooden or metal forms (edging) around the perimeter to contain the concrete and define the shape. These forms must be level and secured firmly because wet concrete weighs roughly 150 pounds per cubic yard—unstable forms will bow or shift during the pour.
The forms also serve practical purposes: they're your control joints, helping manage concrete expansion and contraction due to temperature changes. Contractors typically space control joints every 4–6 feet to guide where cracking will occur (rather than random cracking).
Concrete Mix and Pouring
The concrete mix for patios typically uses a 3,000–4,000 PSI strength rating (higher strength for areas where you'll park vehicles occasionally). Standard mixes include portland cement, sand, gravel, and water; some contractors add air entrainment or fiber reinforcement for freeze-thaw resistance in colder climates.
Once the concrete truck arrives, the crew has a limited window—usually 90 minutes before the concrete begins to set. They'll spread and level the wet concrete using screeds (straightedges), removing air pockets and excess material. On a 400-square-foot patio, pouring typically takes 2–4 hours.
Finishing and Curing
After pouring, the concrete surface is finished to your preferred texture. Common options include:
- Broom finish — adds slip resistance; most affordable ($0–$2 extra per square foot)
- Smooth trowel finish — sleek appearance but slippery when wet
- Exposed aggregate — reveals pebbles for a decorative, textured look ($3–$8 extra per square foot)
- Stamped patterns — mimics stone or brick ($8–$15 extra per square foot)
The contractor may also cut control joints at this stage or wait for the concrete to partially set before cutting them with a saw.
Curing is critical and often overlooked by homeowners. Concrete needs 7 days of moisture to develop proper strength, so contractors may mist the surface or cover it with plastic sheeting. You shouldn't walk on it for at least 48 hours and shouldn't place heavy furniture or vehicles on it for 1–2 weeks.
Common Installation Mistakes to Avoid
Watch out for contractors who:
- Skip or skimp on gravel base preparation
- Pour concrete in direct sunlight or freezing temperatures
- Don't control joints properly
- Rush curing time
- Don't slope for drainage
Frequently Asked Questions
Q: How long before I can seal my concrete patio? Wait 28 days after installation before applying sealer; the concrete needs time to fully cure and dry out completely.
Q: What's the difference between a 3-inch and 4-inch slab? A 4-inch slab is the standard for residential patios and light vehicle traffic; 3-inch is thinner, more prone to cracking, and generally not recommended unless it's purely decorative with no traffic.
Q: Can I install a patio myself? DIY is possible for small projects, but site prep, forming, and finishing require precision—mistakes show immediately and cost thousands to repair; hiring a pro is usually worth the investment.
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