How to Elevate a Sunken Concrete Patio

A concrete patio can sink and crack over time. Concrete is subject to weather and ground changes. Freezing and thawing cycles cause concrete to crack, break, and in some cases, sink. Although this usually only occurs in sections, it's important to level the entire patio for safety reasons and a more beautiful appearance.

Instructions

1. Consider slabjacking as an alternative to removing cracked, sunken or uneven concrete. Slab jacking is a process where cement slurry is pumped under the concrete to lift it to its original grade. Slabjacking also fills in unseen gaps under the concrete which helps divert water away from the foundation.

2. Level small sections of sinking concrete by cutting away the sunken piece, lifting it out with a crow bar, filling the area with sand and replacing the slab you removed. Use a tamping machine to tamp the sand down to a hard, level surface before replacing the slab.

3. Use a veneering technique when sections can't be leveled with sand. With a brick chisel and baby sledge, roughen the surface and undercut any edges with a brick chisel and small sledge hammer. Drill small holes in the depressed area with a star drill, small sledge or masonry bit. Mix thin mortar in the depression and level it. Let stand for 30 minutes and finish with a trowel or broom.

4. Break the concrete patio at the control cracks or expansion joints and lift out the sunken slab. You'll need lots of help for this. Use pea gravel, stones or bricks to make the surface underneath the slab more stable and fill in with sand. Level the area and replace the slab.

5. Level an entire sunken and broken concrete patio by veneering the entire surface area. Remove any broken or cracked pieces of concrete and wash entire area with a hose. Make sure the patio is very clean. Build a wooden form around the patio 2 to 3 inches higher than the existing surface. Fill in any holes or depressed areas with sand and tamp in place until level. Fill the entire patio with new concrete and broom or trowel to finish.

Tips & Warnings

• Add concrete stain to old concrete to liven it up and give it a totally updated look.

• Use existing lines of broken concrete to create a natural stone look. Level broken areas one at a time and mortar in with sand. This will give your old patio a new look without replacing any concrete.