We all know the saying and most of us probably will step a little further just to avoid hurting dear mom. When it comes to decorative or stamped concrete, pride and expectations are often hurt more when unsightly cracks appear. Cracks in a decorative surface tend to send ugly signals that tell people “stamped concrete cracks.” Being true in a sense, as with almost any concrete, proper planning along with setting customer expectations will help a lot. Despite the choice of pavers providing a longer list of eventual unsightly issues, concrete cracks are the biggest push people feel when making that decision to avoid decorative concrete.
Stamped concrete allows you to provide your client a unique surface that can mimic almost any type of natural material surface. Flagstone, cobble stone, slate tiles and even stunningly beautiful wood planking can be done these days with reliable products like those produced by Walttools. Despite knowing bad things can happen, the client simply is not going to easily accept a completely random crack running across their prized Weatherwood plank concrete patio, and quite frankly, they should not have too.
Control joints are probably your biggest method to reduce or control the risk of random cracks. Simply put, they are deep, man-made lines meant to provide a weak point in that concrete. By providing a slew of strategic scored areas for which the concrete to relieve itself(crack), you hope to prevent that slab from just choosing its own path. When long slabs are involved or a slab that encompasses an existing structure expansion joints are necessary along with control joints to minimize cracking. Another way to ensure the slab will crack within a provided joint is to prepare an even subgrade (uniform thickness- no undulations). An uneven subgrade is like putting control joints on the underside of the slab.
The tough part is deciding how to incorporate the various ways to provide the control joints in a decorative pattern while not drastically hurting the overall look. The stamp pattern chosen will really dictate your approach.Long, straight linear control joints do not always look so natural running across your meandering random fieldstone pattern. At some point you really have no choice but keep in mind that keeping your client in the loop about the purpose of such treatments will reassure them that you are doing your best to preserve their surface longevity long term.
For most stamping jobs, saw cutting your joints the following day is standard. This reduces the marring of the surface from the tools and is usually soon enough to prevent early movement cracks. In general, early-entry cutting is hands down the least noticeable and most efficient way to control cracks in concrete. Depending on the pattern and the orientation of the pattern lines, you may have to adjust your standard “every 8-10 ft rule” that you use with your regular flatwork projects. Being able to place a control joint within a current pattern line is pure joy for all so plan for it when you can. When using seamless texture skins such as Walttools Presidential slate, you have more options. Finishers can often groove their joints during the normal finish process and then proceed with their texture skins. This method will often crush in the grooved lines a bit but that often leads to a more natural “stone slab” sort of look.Those grooved joints can then be saw cut the following day with little issue. If you are not a fan of grooving, then simply proceed with your next day saw cutting.If early cracks do appear (even before the next day) you will really want to consider being quite aggressive with the placement and depth of the saw cuts near that crack to draw that relief into that joint and often stop that crack in its tracks. In addition, do not neglect to use a good quality curing type decorative sealer such as the Walttools Stampsheen line as soon as you can to promote a steady cure of that slab.
You did everything and still, that random crack breaks through. Now what? This can and will happen sometime and if you were proactive with this topic to your client, it should be a minimum issue. Instead of your client looking upon you as inept in your work, they will acknowledge that you did what you needed to do to prevent a much larger issue down the road. Communication about this issue with your customer is of utmost importance. They will appreciate your personal concern for their project and cast little blame. Do not fail to do this part of your service as this is your best way to preserve your credibility. If you get your customer involved in the decision making process about the reason for joints, the location of joints and the aesthetics of the joints they will be appreciative.