I have just purchased a house in Warfield. The cement patio slab in the back yard is badly cracked and sloping toward the basement wall. I want to resurface the cement with one of those cut pea gravel surfaces that I’ve seen on driveways down at the coast. How do I go about doing this?

From your description, a terrazzo concrete finish is probably what you are thinking of creating. To understand if it can be constructed over your existing concrete slab, it may be necessary to explain the techniques you will need to employ to achieve a terrazzo finish. Here is one traditional method.

After the concrete slab has been cast and before it has fully set, pea gravel is worked gently and partially into the concrete surface. As the concrete dries, the pea gravel bonds with the concrete and becomes permanently fixed to the surface of the slab. Now the real work begins. All the raised, rounded surfaces of the pea gravel are ground flat and polished with a power grinder. The grinding / polishing is finished when the cut stones are ground down to the same surface elevation of the concrete.

Theoretically, you could cast another thin slab over your existing concrete and follow this process to achieve a terrazzo finish, but the chances of the new slab cracking are significant. Because this is a work-intensive process, you will want to increase your odds of success as much as you can. As well, as far as I know, there are no topping compounds that you can roll on or trowel on that will give you a terrazzo “look”.

So the best strategy will be to remove the existing slab and re-cast a new one. Make sure you put a positive slope on the new slab so the surface water drains away from your foundation wall. Making terrazzo is an art and not all the tricks for success have been included in this description. You may consider hiring an experienced cement finisher to help you with the casting, gravel embedding and grinding processes.  

Back to Questions



This article was written by Steven Cannon, a Registered Building Official and partner in Lynch Building Inspection Services Ltd. of Nelson, British Columbia. It originally appeared in The Nelson Express.

Key words: building, home inspection, house, British Columbia, BC, Castlegar, Creston, Cristina Lake, Edgewood, Grand Forks, Kaslo, Kootenay, Kootenays, Midway, Nakusp, Nelson, Salmo, Slocan, Trail, Yak, Ymir