Repairing a Step Corner
Isn’t it just like a home fix-it expert to suggest “breaking it the rest of the way” as the first step in making a repair. Well, that’s it! To repair a concrete stair — or anything else made of concrete — the first step is to completely remove all loose pieces and to make sure that what remains is solid.
In this article we will show you how to make a difficult stair repair — the easy way. As we just mentioned, the first step in making a solid concrete repair involves the removal of loose concrete, sand, dirt and other debris from the area to be patched. This literally is the most important part of the repair process. A clean, solid base will insure a positive connection and a lasting repair.
Next, two oiled wooden form boards are needed — one for each side of the corner. By the way, it is OK to use plywood. We already know the question, “What do we mean by oiled forms?” Wood is porous and can easily stick to freshly poured concrete. Therefore, wood forms must be oiled to prevent them from sticking to the concrete — like when you grease a cookie sheet or oil a frying pan. Although special light-weight oil is available for this purpose (you got it — it’s called form oil), light weight motor oil can be used instead.
If the concrete being repaired is surrounded by dirt then the form installation process will be simple. Stakes can be driven into the ground and nailed into the forms to hold them in place. On the other hand, if the repair area is completely surrounded with concrete then heavy weights will be needed to hold the forms in place. Flower pots, bricks, and yes, even garden furniture can be used. Which ever bracing method is used be sure to nail the form boards together at all joints (in this case, at the corner). Curved shapes can be formed using several layers of bender board, thin plywood or thin sheets of Masonite. Lay a board onto the surface to be repaired and let one end protrude over the top of the form. The top of the form can then be exactly aligned to the top of the step.
With the repair area thoroughly cleaned and forms properly in place all that is left is to wet the repair area, apply the bonding agent (concrete glue) and fill the hole with the patching compound. Be careful here. Each manufacturer has specific recommendations on how their bonding agent should be applied and how long it should cure (dry) before the patch is made. The best repair is made when the bonding agent and patch material are made by the same manufacturer. Although you can make your own patching compound from 1 part Portland cement mixed with 3 parts sand and 1/4 part hydrated lime, we strongly recommend that a commercial latex patching compound be used. These compounds are strong, flexible and adhere well and are available in smaller quantities, making them easier to handle and more cost effective. Once the patching compound has been placed, it will have to set up for a while before it can be troweled, edged and/or broomed.
Once the patching compound is in place it should be tamped gently with a block of wood or a concrete trowel to insure that all cracks and crevices are completely filled. After tamping. the exposed areas will need to be “finished” to match the undamaged, adjacent surface area. If the patch is small enough a putty knife cab used to do the initial surface smoothing. For larger areas a metal, concrete finishing trowel should be used. Once the surface is smoothed an “edging tool” can be used to form a curved edge if one exists. Before going to the store to purchase an edging or nosing tool cut a pattern of the shape of the stair edge on a piece of paper. This can be used at the store to purchase the proper tool. Trowel the flat surface first and then trowel the rounded portion. When this is done the final phase of finishing can be done. The forms are normally removed before the patch can be completely troweled, nosed and finished. The removal should be done very carefully to prevent damage to the patch.
Most exterior concrete surfaces have a slightly rough finish to prevent slipping when wet. The most common finish is the “broom finish”. Once the concrete has had a chance to become firm it is brushed with a broom — hence, broom finish. A similar look can be achieved for a small patch by using a stiff paint brush instead of a broom.
Once the repair is made you may want to look into the prospect of “staining” the entire area with a concrete stain. Doing so will make the area look fresh and new. And, good luck!