Install a Stamped Concrete Patio Over an Existing Patio
When it's time to update your yard or landscape, consider laying a stamped concrete patio over your existing patio if its surface is in good condition. Diligent cleaning and preparation will produce a beautiful, durable new patio surface. Use the guidelines below to install a stamped concrete patio.
Step 1: Measure the Slab and Order Supplies
Take the measurements of the slab and order sufficient mixed concrete, color hardener, stamp mats, releasing agent and colors to lay a 1-inch depth of stamped concrete atop your patio in your chosen pattern.
Step 2: Clean and Inspect the Existing Patio Slab
Sweep and vacuum the existing slab, and wash it with warm water and liquid degreasing detergent. Dry it with a leaf blower or wait 12 hours to let it air-dry. Inspect the entire surface on your knees with the handheld spotlight to check for cracks or sunken areas. Mark these with sidewalk chalk for repairs.
Step 2: Perform Needed Repairs on the Slab
Fill even hairline cracks with cement paint. For small holes and depressions use cement filler, applied and smoothed with a trowel. Allow the cement filler to dry for 6 hours then sand the spot so it is level with the surface.
Step 3: Pour the New Concrete
Pour the new concrete on a warm but not hot day, with no forecast of rain for 24 hours.
Step 4: Add the Color Surface Hardener
The color surface hardener performs many functions, including strengthening the concrete's pressure tolerance to 6000 psi, improving water resistance, adding color, and setting the "plastic" consistency of the concrete to lay the stamping mats. Color hardener is shaken on from large powder containers and pressed into the concrete with a bull float.
Step 5: Apply the Releasing Agent
The releasing agent adds the shading and contrast color and enables you to lift the stamp mats off the concrete. Most of it is removed once the stamping is done.
Step 6: Press the Stamping Mats into the Concrete
Starting at the edge nearest the house, lay and press down the stamping mats with a tamping mallet. Leave the stamp mats in the concrete for about 10 minutes to imprint a clear pattern. Lift and move them carefully across the patio until the entire area is stamped.
Step 7: Chisel in the Control Joints
Following dominant pattern lines, use a powered masonry saw to cut in control joints 1/2 inch deep. Allow the patio surface to dry and harden overnight.
Step 8: Add Other Colors
Add layers of powdered color one at a time, waiting 6 to 8 hours between colors for them to set firmly.
Step 9: Seal the Surface
Apply a thin coat of non-skid acrylic sealer over the entire patio with a paint roller, allowing it to dry for 8 hours.
The new stamped concrete surface of your patio should last for as long as you own your house. Apply fresh sealer every 3 years to enliven and protect the color.