Concrete porches may begin to crack where they meet the house. This is caused by the phenomenon of "settling," in which the home's foundation actually sinks into the ground over a period of many years. With this shift occurring, the concrete porch will start to visibly separate from the residential structure. To fix this problem, you only need to bridge the gap, using newly mixed concrete. While this may seem like a task only a contractor can do, you can do it yourself with a few common masonry tools and materials.
Clean out the separated area between the house and the concrete porch using a shop vacuum to remove all debris.
Place a wheelbarrow near the separation and combine one part cement with three parts masonry sand, then dampen with a hose.
Stir up the cement and sand with a masonry hoe, adding more water as necessary. The mixture should become a mud-type consistency.
Open a can of concrete bonding agent and pour it directly into the separation between the porch and the home.
Tip the wheelbarrow up, allowing the concrete to pour into the gap. Fill the gap completely, then smooth it with a trowel. Scrape up excess concrete as necessary, smooth again, then let dry for 24 hours.
Apply a coat of concrete sealant to the patch using a paintbrush once the concrete has completely dried. Let the sealer dry for another 24 hours to finish the repair.
Vacuum out the gap between the porch and the house with shop vac, leaving no fragments of concrete inside the crack.
Combine 3 parts masonry sand with 1 part Portland cement in a wheelbarrow and mix thoroughly with a masonry hoe.
Wet the dry sand/cement mixture with a garden hose and continue to mix but do not saturate the dry ingredients. Too much water will turn the mixture into what brick layers call "soup." It should have a mud-like consistency.
Open a can of concrete bonding agent and pour it into the separation crack, lining the crack with the liquid bonding agent.
Tilt the wheelbarrow up immediately, pouring the wet concrete into the separation crack until it is full. Smooth the wet "mud" with a trowel and let it dry and harden for 24 hours before walking on it.
Cut the tip of the concrete-repair caulk tube at a 45-degree angle with a utility knife and insert the tube into the caulking gun.
Force the caulk into any cracks in the porch's surface that are larger than 1/2 inch wide.
Smooth the repair caulk with a putty knife.
Mix 2 1/2 qts. of water with the entire 20-lb. bag of concrete resurfacer in a 5-gallon bucket. Mix the materials with the drill motor for two minutes.
Pour the mix out of the bucket and onto the surface of the porch while quickly spreading with the steel trowel.
Run a moist broom across the surface of the concrete when it loses its wet shine, yet is still not fully cured. Allow the porch to air-dry for 24 hours.
Remove debris from the surface of the concrete porch by sweeping it thoroughly with a broom. Ensure the concrete is free of all debris before continuing.
Pour water-based concrete cleaner in a hand sprayer. Stop pouring when the cleaner level reached the "Full" line marked on the outside of the sprayer container. Pump the handle to pressurize the sprayer. Wet the concrete porch with water from a garden hose. Spray concrete cleaner on the wet concrete. Scrub the area with a stiff-bristled brush. Wash the cleaner from concrete. Pour the remaining cleaner back into its container. Allow the concrete to dry for 24 to 48 hours.
Fill the hand sprayer with concrete sealer. Spray sealer around the edges of the concrete porch. Spread the sealer around the edges of the concrete with a paintbrush.
Spray sealer on the remaining area of the concrete porch. Spread the wet sealer across the porch floor by rolling a paint roller across the floor in long, even strokes. Allow the sealer to dry for two to four hours. Apply a second application of sealer to the floor, if needed. Allow the porch floor to dry for 24 hours.
Rent or purchase a pressure washer from your local hardware or home store. A 500 to 1500 psi washer will do.
Put on your protective eyewear. Remove everything off of your porch.
Scrub your complete concrete porch with a damp sponge and dish soap.
Screw a water hose into the pressure washer. Plug the pressure washer into a GFCI (ground fault circuit interrupter) outlet. Turn on the water source. Switch on your pressure washer.
Wash off your entire porch with back and forth sprays of your pressure washer. Start on one end and walk backwards as you wash the porch so you don't step in the wet, but clean areas. Allow your concrete porch to air dry for several hours and replace your items that were previously on the porch.
Clean the porch of debris, dust and dirt by using a shop vacuum. Clear all furniture or other movable pieces from the porch floor.
Fill a garden sprayer's tank with a concrete degreaser, and spray it evenly on the porch floor. Let the degreaser set for 25 to 30 minutes, and then scrub it into the concrete with a nylon brush.
Spray down the floor with a garden hose to clear away the degreaser and any remaining debris. Wait for the porch to dry before beginning the leveling process.
Mix self-leveling compound and water in a small bucket using the ratio instructed on the packaging.
Pour the compound from the bucket onto the porch floor, and push it into low and unlevel spots with a steel trowel. Work quickly, as the compound will begin to set within several minutes of application. After you have spread it into the unlevel spots, allow it to self-level and cure for 24 hours before using the porch.