While concrete is one of the most widely used materials due to its durability, it’s still prone to damage. Areas like the basement, laundry room, garage, and landscaping around the home can be particularly vulnerable to imperfections. Cracking, sinking, heaving, and sloping can occur since they are usually high traffic areas and susceptible to deterioration due to chemicals such as salt.
If you have a noticeable gradient in your home and wonder how to level a concrete floor that’s sloped, here are the steps to repair the problem.
1. Identify the Cause
The first step in addressing a sloped concrete floor is identifying the cause of the failure. This will determine how the concrete will be repaired or whether it needs to be replaced entirely.
If the concrete slab has sunk or heaved, it is paramount that the failure’s initial cause is addressed before anything else. You will continue to run into problems after repairing the concrete slab or floor if you don’t address the initial cause.
2. Inspect the Material Underneath
When you repair concrete floors, the first step is always to examine the type of material underneath. Often, we find void space under a concrete floor due to settlement or expansion of the subgrade. If a frost-susceptible material is bearing the concrete floor, it will be prone to expansion and shrinking.
Clay, for example, will expand in moist conditions and will shrink when dry. Remove the clay at least to a native elevation and below freezing point and compact a non-frost-susceptible subgrade on top. The new concrete floor will then have a strong base to load onto. The soils’ bearing capacity to support the concrete is the most critical aspect in constructing a concrete floor.
Should the subgrade below the concrete be of appropriate bearing capacity and the concrete is structurally sound and only require re-surfacing, you can pour concrete on top of the existing floor. Here’s how to do it:
3. Prepare and Clean the Existing Concrete Floor
Prepare the surface of the concrete by removing any loose or deteriorated areas. To do this, remove the baseboards, furniture, appliances, and anything else on or surrounding the floor. Then give the floor a good cleaning using a special concrete cleaner to remove any grease and oil stains, dirt, and debris.
The cleaner the floor is, the better the new layer of concrete will adhere to the old floor. If there are still imperfections on the concrete, like chipped or flaking areas, use a metal scraper to remove them. To finish, vacuum the entire area.
4. Mark Off Sloped Areas and Grind Down High Points
Next, identify and mark off the sloped areas using a leveling bar along the floor. Using a concrete grinder, shave down high areas by moving the machine back and forth until each spot is level with the rest of the floor. Once done, vacuum up any dust and debris.
5. Prepare Bonding Agent
Once the concrete is clean and dry, install a mechanical bonding agent such as steel dowelled into epoxy to stick the two vintages of concrete together.
6. Prepare Leveling Concrete
Using a mixing drill and the right water ratio, carefully combine the concrete compound until it’s dense and easy to pour. Depending on the application of the slab, floors, steps, and commercial slabs, the thickness and add agents in the concrete will adjust accordingly.
7. Apply the Leveling Concrete
Before you begin pouring the concrete, first cover up any drains. Then, using a squeegee, disperse it evenly into each of the corners and edges while having a leveling bar on hand to ensure you are leveling it out as you go.
Since the concrete will start to dry in about 20 minutes, work through this step as quickly as you can. The dry time can vary depending on the manufacturer, but the average timeframe is about 48 hours before furniture can be moved back onto the floor.
This entire process can take approximately two days to complete from start to finish.
