Decorative Concrete Stamping
Stamping Concrete 101: The Basics
by Susan Brimo-Cox
is booming. Potential customers are learning about it in consumer magazines, on HGTV and at home and garden shows, inspiring them to think of adding features such as stamped driveways, faux rock walls or polished concrete floors to their homes or businesses. If you haven't received a request for decorative concrete yet, chances are you soon will.
And if you are thinking about expanding into this lucrative niche, stamped concrete is a good place to start. There is a learning curve, but the techniques of imprinting can be mastered if you have a good grasp of the placing and finishing skills needed for basic concrete.
Site preparation and placement of concrete is the same for stamped concrete as it is for any slab. “The base preparation should be the same as for any concrete application,” observes Clark Branum, area manager for Rafco Products. But remember, your sub-base is an important foundation to your decorative work. You want a “compacted crushed rock base with no standing water,” Branum says.
The type of mix and aggregate will vary with the regional requirements for freeze and thaw, as well as structural requirements. Don't feel shy about asking the experts. “Most people do not realize how many experts they have available to them,” says Steve Johnson, director of marketing for new product development at Solomon Colors. “The first person you should talk to is your ready mix producer.”
The thickness of the slab depends on the intended use, but typically it is at least 4 inches. Reinforcements should be placed according to standard concrete practices.
The framework for stamped concrete should be installed the same way as for traditional concrete, with a couple extra considerations, says Richard Cofoid, national sales manager for Increte Systems Inc. If you are stamping a square pattern, make sure your framework is square. Be sure to drive the tops of stakes even with or below the top of the framework so your stamping tools don't get hung up. And, very importantly, protect all adjoining areas by masking them off with duct tape and plastic. Then place, screed and float the concrete as you would a standard slab.
If you're new to stamping concrete, be careful not to bite off more than you can chew. While an experienced crew can stamp 800 to 1,000 square feet in a day, novice stamping crews should limit their pours to no more than 400 square feet on average. “Skill, job access, weather conditions, manpower, stamp pattern and color hardener choice are all considerations,” says Doug Carlton, owner of Carlton Concrete L.L.C.
Also, keep in mind that walls and protruding obstacles will slow the process down.
The easiest stamps to start out with are borders along a broom finished job, Johnson says.
If the whole surface will be textured, choose random patterns. “Beginners should start out with textured stone or larger patterns with no detail,” says Russell Rodoni, owner of Sierra Design Concrete.
Texture mats that leapfrog over each other are easier than ridged tools that fit together like a puzzle. Most experienced contractors say to avoid interlocking patterns until you get a feel for the imprinting process.
Renting imprinting tools is a good option if you're just starting out, because some patterns and tools can be costly. “Rent twice the amount you think you will need,” Carlton recommends.
Does integral color add value to the stamped concrete job? It depends who you talk to. On one hand, integral color offers limited color choices, and it is hard to match from pour to pour and day to day. But, on the other hand, it is faster and less messy than other coloring techniques. In addition, contractors just starting out in stamping may find imprinting colored concrete is easier. “Not because it is better, but there are fewer steps to be concerned with,” observes Scott Thome, director of product services with L.M. Scofield Co.
What it seems to boil down to is personal preference. “Beauty is in the eye of the beholder,” Johnson says. “Realistic to one may look eclectic to another.”
Most contractors use dry shake color hardener to add color to their stamped concrete. Available in a wide variety of colors, it is easy to match if repairs are needed, and it increases the surface strength of the concrete. But be aware that use of color hardener adds time to a job, requires more labor and can be messy.
Color hardeners are typically applied in several passes after the bleed water has evaporated. Many contractors broadcast by hand, though Rodoni recommends broadcasting with a splash brush to avoid streaking. Broadcast the powder evenly, allowing it to wet up, and work it in with a bull float. After the final pass has been applied, finish-trowel the surface.
According to Cofoid, a 60-pound bucket of color hardener will generally cover 80 to 100 square feet; for lighter colors you'll need to use more. Make sure you follow the manufacturer's recommendations, as each manufacturer has a prescribed rate of application for certain colors.
Another method of coloring the surface is to use chemical stains, but this is “definitely not for beginners,” Rodoni says. |
