Stamping concrete gives a textured pattern to an otherwise flat patio. Stamps come in different patterns to impress elaborate designs or resemble cobblestones, brickwork and other surfaces. You can only stamp concrete when it is still wet from a pour. To add texture to an existing patio, pour a fresh layer of concrete over the old and stamp it, provided the existing patio is in good condition.
When you pour a new layer of concrete over an existing patio, the integrity of the new surface will only be as good as the one beneath it. If the existing patio has cracks and pits, fill them with a patching compound or caulk to level the surface.
Types of Stamps
You can use a textured roller or individual hand stamps to impress patterns in concrete. Purchase multiple hand stamps if you're pouring a large surface to ensure the entire surface can be covered before it starts hardening. Consider using interlocking stamps, which make it easier to press the stamps so the joints align. The styles of patterns range from basic brick work, to just about any pattern that you can arrange tiles and natural stones in. If possible, choose a pattern that will accentuate existing stonework in your yard or on your home's exterior.
The new concrete layer will best adhere to your existing patio if you first clean it thoroughly. Plan to scrub or power wash the patio as any debris trapped will weaken the bond between the two slabs. Stamps must be set within 15 minutes of pouring the concrete so you should place all of your tools within reach to avoid a last-minute scramble. Dry-lay the stamps next to the patio in the pattern in which you plan to arrange them. Practice interlocking the sides if applicable. Leave the stamps in the correct order next to the site so you can press them quickly and in the right order.
Installing a stamped concrete patio over an old surface is a two-part process: First you pour the new concrete, then you press the stamps. Apply a bonding adhesive over the existing patio and a thin coat of bond release agent over the stamps so they don't stick to the concrete. Gather a small team of people to help level and smooth the surface once the concrete is poured. You only need to pour a layer about 2 inches thick, as the existing patio and foundation beneath it forms a strong base. Stamp the patio in the order that the new concrete was poured, lifting the stamps straight up with the handles so you don't accidentally drag them over the surface.