Concrete Patios in St. Louis, MO

Concrete patios get a lot of use in St. Louis, where Wikipedia's climate table puts the average July high near 90 degrees and the season for eating outside runs from spring into fall. A concrete patio gives you a flat, solid surface that needs little more than sweeping and an occasional sealer, and it can be finished plain, textured, colored or patterned. HomeGuide's patio guide lists plain concrete patios at $4 to $12 a square foot installed.

Sizing it right

Most people who regret a patio regret that it is too small. A table for six with chairs pulled out needs roughly a 12-foot square on its own. Add a grill with space to stand, a walkway past the table and a couple of lounge chairs, and the slab heads toward 15 by 20 feet. On narrow city lots, where the back yard runs between the house and an alley garage, we often work the patio into a path to the garage or gate. At the estimate we mark the outline on the ground so you can stand in it before deciding.

Water away from the house

Many St. Louis homes have brick or stone foundations that are a century old, and a patio poured against one must not send water toward it. We typically set a fall of about a quarter inch per foot away from the house and check where downspouts empty today. If a downspout lands where the patio will go, it gets extended past the slab or redirected. Where a yard already drains across the patio area toward a neighbor or the alley, we keep that path open.

Finishes

• Broom finish: simple, grippy and the most economical, HomeGuide lists $6 to $13 per square foot.
• Exposed aggregate: stone revealed at the surface, good traction, hides dirt, $7 to $18 per square foot.
• Integral color or stain: color through the slab or applied to the surface.
• Stamped: slate, flagstone or brick patterns, covered on our stamped concrete page.
• Saw-cut patterns: a grid or diamond layout cut into a plain slab that doubles as control joints.

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How we build one

Turf and topsoil come out first. The subgrade is shaped to the planned slope and covered with a compacted crushed-stone base for even support and drainage. A standard patio is 4 inches thick, and HomeGuide recommends 6 inches with reinforcement for heavy loads like hot tubs or outdoor kitchens. We use air-entrained concrete outdoors, finish and edge it, cut joints and place an isolation joint where the slab meets the house so it can move without pushing on the foundation.

Replacing an old patio

It is time to replace when a patio tips toward the house, has cracks with raised edges, has lost its surface to scaling, or has sunk so the step from the back door keeps getting taller. A patio that is intact but has settled may only need leveling, and we price that when it is a real option.

Care

Sweep and rinse it. Put planters on feet so water does not sit under them. Reseal every few years, sooner on colored or stamped surfaces. Use sand, not salt, on any patio path you walk in winter, and keep downspouts emptying beyond the slab.