"Drawing the Line" – A scored concrete patio
When it comes to home renovations, some neighbors can be competitive. The owners of this house lived in a retirement community. Everyone in the community seemed to want their homes to look good. Renovations were popular.
Decorative concrete can be a great way of improving the appearance of a house, so the homeowners contracted us to lay down a scored concrete patio and sidewalk in the front of the house and a scored concrete patio in the back.
In stamped concrete projects like this one, we lay down a thick concrete overlay on top of the existing concrete floor. At first, the new layer is smooth and lacks texture, but while the layer is still wet, we then add textures and patterns that imitate the appearance of stone.
These effects can be created through one of two methods. In the first method, we use prefabricated mats that has both a stone-like texture and a pattern with the shapes of individual stones that we then stamp (press into) the wet concrete.
In the second method, we use another type of prefabricated mat that only has the stone-like texture, no shapes of the individual stones. We stamp this into the wet concrete, wait for it to harden and then use special tools to score (cut) the shape of the stones into the concrete.
We prefer the second method, since it gives us greater control, especially when we run into unexpected problems.
At this house, the second method turned out to be the better option, especially for the scored concrete patio in the back of the house.
The first part of the project went smoothly; we started in the front of the house with the sidewalk leading up the front porch without any trouble. We laid down the overlay material, and while it was wet, we applied a texture that imitated ashlar slate.
After the new concrete layer had dried, we used blue chalk lines to create guidelines on the hardened concrete, and then we scored a tile pattern into into the concrete. The tile edges were parallel with the edges of the patio and the sidewalk.
Next, we moved to the back patio. After cleaning the existing concrete and laying down the overlay material, we stamped the ashlar slate texture into the wet concrete overlay and let it dry.
The plan was to lay out the tile pattern the same way we did in the front, parallel to the edges of the patio. Before scoring, we marked the places where the tiles would be scored; It was at this point that we ran into a problem.
The contractors who’d laid down the original concrete floor had also scored control joints into it. The back patio was a big slab of concrete, about ten feet wide and 20 feet long. Whenever the ground it sits on becomes wet, cold, hot or dry from drought, the ground can expand or contract.
This causes movement and can lead to cracks forming in the concrete. These cracks will form at the concrete’s weakest point; a control joint can helps determining where the cracks appear.
The joints are typically thin cuts made into the concrete, at a depth of about ¼ of the thickness of the floor. This weakens the concrete along the cut. As cracks form in the weakest part of a concrete floor they tend to inside the control joint where they are mostly invisible.
Control joints can be pleasing in appearance. If the cracks form only in the joints, the joints can also help to maintain the overall appearance of the concrete floor. We can’t cover control joints as, over time, we will end up with a crack where they were.
We had noticed the control joints right away when we started the project but it was only after laying out the tile pattern in the back that we noticed they were off-center. The pattern we laid out on the floor which included them just didn’t look good.
We spoke to the homeowners, and decided to shift the angle of the tile edges, instead of parallel to the patio edge we made them at a diagonal 45 degree angle.
We washed off the old chalk lines and laid down new ones. The result was a scored concrete patio with diagonally placed ashlar-like tiles. The result wasn’t what we had originally planned but we able to pivot and in the end it looked great.
