Concrete patios in Flint and Genesee County

Decide the size with furniture, not a tape measure

Lay out your table, chairs and grill on the lawn, or mark the outline with a garden hose, and walk around it. As a guide:

• 12 × 12 ft (144 sq ft) fits a table for four with room to pull the chairs out.
• 16 × 20 ft (320 sq ft) fits a dining table, a grill and a couple of lounge chairs.
• 20 × 24 ft (480 sq ft) gives you separate areas for eating and sitting, or room for a fire pit.

Adding a few feet now costs far less than adding a strip later, and a later addition never quite matches in color.

What a patio needs to last here

• Slope away from the house. An eighth to a quarter inch per foot is enough to keep rain and snowmelt off the foundation.
• Four inches of air-entrained concrete on a compacted gravel base. This is the same recipe as a driveway. Patios skip the base more often than driveways do, and it shows a few winters later.
• A gap at the house. The slab should not be bonded to the foundation. A strip of expansion material lets the patio move with the frost without pushing on the wall.
• Control joints laid out so each panel is roughly square.

Plan these before the pour

All of these are cheap to do first and expensive to do afterward.

• Sleeves under the slab for a gas line, low-voltage lighting or sprinkler pipe. A length of PVC costs a few dollars.
• Downspouts. Route them under or around the patio so they do not empty across it and turn it into ice.
• A hot tub. A filled tub weighs several thousand pounds. Tell the contractor where it will sit so that section can be poured thicker and reinforced.
• A roof, pergola or screened room. Posts that hold up a roof need footings that reach below the frost line, which is 42 inches in Michigan. A four-inch slab is not a footing.
• The step at the door. Decide whether you want a landing, one step or two before the forms are set.

Finishes

A broom finish is the standard: good grip when wet and the lowest price. Exposed aggregate shows the stone in the mix and hides dirt well. Stamped and colored concrete imitates stone, brick or wood and costs more to pour and to keep up. See stamped concrete for the trade-offs.

What a patio costs

Plan on $8 to $14 per square foot for a broom-finish patio and $15 to $25 for stamped. A 16 × 20 ft patio therefore runs about $2,600 to $4,500 plain or $4,800 to $8,000 stamped. Small patios sit toward the high end per square foot, because the crew, truck and setup cost about the same whatever the size. Back yards that a concrete truck cannot reach also cost more, since the concrete has to be wheeled or pumped in.

Common questions

Do I need a permit for a patio?

An uncovered patio at ground level often does not need a building permit, but zoning rules on setbacks and how much of the lot can be paved still apply, and lakefront lots are usually stricter. Anything with a roof or attached to the house generally does need one. A quick call to your city or township building department settles it.

Concrete or pavers?

Plain concrete costs less and has no joints for weeds. Pavers cost more but can be lifted and reset if the ground moves. Stamped concrete lands between the two on price.

Can a patio go right over my old one?

If the old slab is cracked or has sunk toward the house, it should come out. Read about removal and replacement.