How Much Concrete for a 20×20 Patio

20×20 Concrete Patio: Complete Planning Guide

A 20×20 foot patio provides 400 square feet of outdoor living space — enough for a full dining set, lounge area, and grill station. At nearly 5 cubic yards of concrete, this project requires a ready-mix delivery and is best done with 3–4 helpers or a professional crew.

Material Breakdown

Material	Quantity	Estimated Cost (2026)
Ready-mix concrete	5.5 cubic yards (includes 10% extra)	$660–$935
Gravel base (4")	5 cubic yards	$100–$175
2×4 form lumber	11 boards (10-foot)	$44–$66
Wire mesh (6×6)	4 sheets (5×10)	$40–$80
Expansion joint material	40 linear feet	$15–$25
Curing compound	2 gallons	$30–$40

Total DIY cost: $900–$1,300. Professional installation: $3,500–$6,000 depending on finish (broom, stamped, exposed aggregate).

Why Ready-Mix Is Essential at This Size

At 4.94 cubic yards, mixing bags is impractical — you'd need 222 bags of 80-lb mix. That's 8.9 tons of concrete to open, pour, mix, and place before it sets. A ready-mix truck delivers everything pre-mixed and can pour 5 yards in about 30 minutes. Even with the short-load fee (if under the minimum), it saves hours of back-breaking labor and produces a more consistent, stronger slab.

Design Considerations

• Slope for drainage: A 20-foot span needs at least 2.5 inches of fall (1/8" per foot) directed away from the house. Verify this with a level on the forms before pouring.
• Control joints: At 20×20, you need joints creating sections no larger than 10×10. That means one joint down the center in each direction, dividing the patio into four 10×10 quadrants.
• Expansion joint against house: Where the patio meets the foundation, install 1/2" asphalt-impregnated expansion joint material to prevent cracking from thermal movement.
• Stamped or colored finish: This is the time to decide. Color hardener adds $0.50–$1.00/sqft ($200–$400). Stamping adds $2–$4/sqft but requires experienced finishers working fast. Exposed aggregate costs $1–$2/sqft extra.

Pro Tips

• Schedule the truck for morning. You'll have cooler temperatures and more working time before the concrete sets. Afternoon pours in summer can set too fast for proper finishing.
• Have a backup plan for excess. Order 5.5 yards to be safe. If you have 0.5 yards left over, pour a small stepping stone pad, fence post bases, or even fill a wheelbarrow path mold.
• Coordinate helpers in advance. You need at minimum: one person directing the chute, one screeding, one floating, and one edging. Brief everyone before the truck arrives.

Common Mistakes

1. Not confirming truck access. Ready-mix trucks are 40 feet long and weigh 60,000+ pounds loaded. Verify your driveway and yard access can handle the truck, or plan for a concrete pump ($200–$400 extra).
2. Underestimating time pressure. Once the truck arrives, you have about 90 minutes before the concrete starts to set. Every minute counts — no coffee breaks during a pour.
3. Forgetting the expansion joint. Without expansion material between the patio and house foundation, thermal expansion will crack one or both. This $15 item prevents thousands in repairs.