Patching a Hole in Your Concrete Slab

One of the more common repair jobs I’m called for are holes in slabs. Many times, concrete slabs are cut and chiseled out to repair underground utilities, sometimes holes are from old age and sometimes holes are even caused by an inferior installation. Whatever your concrete hole problem, use these simple steps to filling a concrete hole and get your slab back to normal in no time fast.

Excavating the Hole

Prepping the hole is important to getting a good, solid pour. Excavate the hole down to the surface of the soil just beneath the existing slab. You should be able to just feel the edge of the old slab with your fingers. Smooth the surface of the soil flat with a small block of wood after you remove any debris like rocks or roots. You will need to treat the soil with bug poison and cut a small piece of plastic if it’s for an interior slab.

Interior Slabs

When the interior of your slab is going to be covered with carpet, tile or other flooring, it’s best to use a self-leveling compound. These typically come in a 1-5 gallon bucket and contain a premixed epoxy that pours directly from the bucket and into your concrete hole. You may need to use a small block of wood to tamp the surface of the liquid concrete as you pour it into the hole. Slightly overfill the hole with the self-leveling concrete because as it dries, it will shrink. Let dry 24-48 hours before covering with flooring.

Exterior Slabs

Since this material needs to match the existing slab as closely as possible, you’ll need to use a dry mix bag of concrete. Pour a 40-80 lb. bag of premixed concrete into a wheelbarrow and mix with a little water. Use a hoe or shovel to mix the water and the concrete together. Add water sparingly as you mix it until you achieve a thick pancake batter-like consistency.

Using a shovel or small bucket, scoop up your concrete from the wheelbarrow, bring it inside and pour it into the hole a little at a time. Fill up the hole and use a small scrap of wood to tamp the concrete once it’s reached the surface. This pounds the aggregate in the mix down and brings the wet slurry mix to the surface, allowing you to get a smooth finish on the concrete. Smooth the surface by using a 2×4 wider than the hole. This will let you drag the board across the top of the new concrete so that it stays level with the existing slab. As it dries, work the surface using a small hand trowel or margin trowel. Once it dries hard enough where no standing water is on its surface, you can completely smooth the surface with a hand trowel or broom finish the surface using a push broom.

Carpet. Wood. Tile. What do you choose? Why not let your floor go naked and use the existing concrete slab for your new flooring material? Can’t be done? Think twice and look at the photo of the finished concrete floor. That’s a smooth finished slab and it looks pretty awesome, eh? It also keeps the house cool in the hot Florida summers and keeps it warm in the winter when the fireplace is burning. Check out these simple tips and basic instructions for finishing your existing concrete slab with a clear coat and revamp your room (or whole home) with an affordable new look.

Prepping the Floor

This is the easy part, provided there aren’t large chunks of mastic or epoxy stuck to the floor. Any serious staining or other damages may not come clean and will leave a permanent stain when the floor is complete.

With that said, if you’re slab looks good overall, you can begin cleaning the surface. Use some warm water and dish detergent to wash the floor using a mop and stiff bristled brush. You’ll need to really clean it good several times to get the area as debris-free as possible. A floor scraper is sometimes required to get rid of any stubborn stuck on material like caulk or joint compound. Let the floor dry for 24 hours and Shopvac the floor before moving to the next step.

Acid Etching

If it sounds dangerous; that’s because it is. While it’s not going to melt the flesh off your bones, it can mess you up if it gets in your eyes or on your skin for prolonged periods. Wear approved gloves, eye protection and clothing when handling the following materials.

In a large plastic bucket, mix one part muriatic acid with four parts of water. Next, use your mop to spread the solution onto the concrete floor. Spread the solution in a random pattern because whatever way you spread the mop across the surface of the concrete, it will show up through the clear coat. Work your way across the well ventilated space and allow it to dry for a few hours. Use a fresh bucket of clean water and mop the space one more time. Allow it to dry for 24 hours before moving to the next step.

Clear Coat

This is the easiest and final step-just don’t paint yourself into a corner. Pour some concrete clear coat into a roller pan. Using a heavy nap roller cover, spread an even amount of clear coat onto the floor; just like you would paint a wall. Work your way across the room, removing any lines or holidays as you go along. You’ll need to let it dry for at least four hours before applying the final coat. Let it dry for 48 hours before moving any heavy furniture onto its surface.

More Great Home Improvement Articles from Eric Brennan

How to Paint a New Metal Door

How to Strip Desk Paint

How to Clean Paintbrushes

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