A broken down piece of concrete magically disappears under a stone pathway laid without mortar or cement.
I am frequently asked to remedy concrete walkways. Sometimes these concrete paths are old and broken down, in other cases, they just aren’t the look the homeowner desires. In most situations, the existing walkway, broken down or not, needs to be removed. This can be expensive and bad for the environment, if a good use can’t be found for the broken concrete. Whenever possible, I try to leave the concrete where it lays and place my stone over it. Dry laid flagstone is stronger and more durable than mortared paving, and it doesn’t matter how messed up the concrete is underneath it. (Mortared flagstone should only be applied to solid slab in good condition.) Laying drystone flagstone over ugly concrete saves money, and avoids filling the landfill with concrete waste. There are two main issues that can come up when taking this approach that we’ll explore below: clearance and drainage.
BEFORE: This little used path wrapped around the back of a lovely Asheville home. The homeowners wanted to pretty it up and maintain access to their backyard.
AFTER: A loose stone pathway winds its way through a field of pea gravel. Instead of removing all the concrete, I placed my flagstone over the top. Stucco became a quick fix for this ugly wall. You might see that it’s being pushed over by the bank behind it. Someday we’ll replace it with drystone!
Dealing With Drainage & Your Stone Pathway
Drystone paths and patios allow water to run over them and percolate through. This prevents pooling and reduces slick spots on the walking surface. It’s important that the top surface of the stone pathway be able to slope gently away from houses, foundations or other areas sensitive to moisture build-up or erosion. It’s equally important that the substrate below the flagstone is also pitched in the proper direction, as some moisture will pass through. This means, when I go over a concrete walkway with stone, I have to be sure the slab is draining in the right direction. This is easily assessed with a level and tape measure. A host of solutions can be considered if the drainage situation isn’t ideal.
Clearance Issues For Flagstone & Steps
Clearance issues are usually the deal breaker for whether a dry stone surface can be laid over concrete. The height of existing thresholds, curbs or steps must be taken into account at all points along the flagstone surface. The risks being that one could create weird little steps, make a trip hazard, or block a door so that it no longer opens! As it happens, so much settling occurs in Asheville homes, old and new, that I can often find the clearance I need, sometimes by replacing awkward and uneven steps with stone stairs that are uniform and solid.
In the image above, the large stone slab that acts as a step was the key to getting the clearance needed to build the path that circled the house. Previously there had been an awkward three inch rise- too tall for a threshold, but not tall enough to be a step. This stone step, at six inches tall, is a real step, consistent with those at the street and that lead into the house.
BEFORE: A broken down set of uneven concrete steps lead to the street. There’s a fourth step hidden in the shadow of the telephone pole. The top step is coming apart and is off center with the steps below it.
AFTER: I had to tear out the bottom three steps, but that was the only concrete removed for the whole project. (Reclaimed by a friend who needs clean fill for another project.) I set the steps further back from the road and gave them a consistent rise over run. I rebuilt the wall, opening the main entryway and making it more welcoming. The steps are now aligned with the path. The steps and wall repairs are mortared; everything else is laid dry.
The homeowners are both craftspeople- he’s a woodworker and she’s a potter. As we stuccoed this old block wall, we embedded ceramic tiles made by the potter. This is a picture of my favorite, a relief print made from a gravestone carving she found at Riverside Cemetery.