Things You'll Need
Pressure washer with fan tip
Concrete repair caulk
Stiff wire brush
3-inch finishing nails
Liquid concrete repair epoxy
Strength, durability and longevity make concrete a common choice for balconies. Over time, however, wear and tear, lack of maintenance, improper installation or exposure to the elements leave the balcony walls or floor appearing rough, cracked or bumpy. Cracks in the concrete not only mar its appearance, but also serve as a structural hazard if left to spread. In general, you should monitor the any crack for six months to ensure it does not increase in size. While you can fix small or hairline cracks yourself, ask a structural engineer to inspect the balcony if the crack is deep or large and determine its root cause.
Repairing Concrete Floor
Clean your concrete balcony floor using a pressure washer fitted with a fan tip. Hold the washer 8 inches above the concrete floor and move it in slow sweeps to remove accumulated dirt and debris, exposing the cracks.
Fill cracks, holes and crevices on the floor with concrete repair caulk. Smooth out the top of the caulk with your finger. Allow the caulk to cure for the time specified on the label's directions.
Prepare concrete dressing according to the manufacturer's directions in a 5-gallon bucket.
Spread the prepared dressing over the balcony floor and immediately spread it out with a trowel, pressing it hard into tiny crevices. Assign a helper to quickly prepare another batch of concrete to pour around the remaining sections of the floor for a large balcony.
Run a medium-bristle broom across the surface of the wet concrete to create a slip-proof surface. Allow the concrete to cure according to the time specified on the manufacturer's directions.
Repairing Concrete Walls
Rub the crack in the concrete wall with a stiff wire brush to remove loose pieces. Use a shop vacuum to remove accumulated debris. Ensure the crack is dry, or direct hot heat from a blow-dryer over the crack for 20 minutes if it is damp.
Hammer 3-inch finishing nails every 12 inches along the length of the crack. Pound the nails halfway into the concrete wall.
Prepare the two-part crack sealer according to label directions on a scrap board. Spread it over the base of the plastic port included in the repair kit. Slide the port over the nail, with the base touching the wall, until it covers the nails completely. Repeat this process to install the remaining ports along the crack.
Spread the repair epoxy into and over the crack and extend it by 1 inch on each side. Pack the epoxy around each port's base and flange. Do not cover the necks of the ports. Allow the epoxy to cure for the time specified on the label's directions.
Insert the tube of liquid epoxy provided with the repair kit into the caulk gun. Inject it into each port until excess epoxy begins to drip. Cap each port with a plastic plug. Allow the filler to cure for five days.
Cut the elongated necks of the plastic ports off with the hacksaw, until they are flush with the surrounding concrete wall.
The responsibility of repair and maintenance of balconies typically falls on its owner. Local buildings codes have set a time frame within which you should have your balcony inspection, for instance, every five years in New York City. In between inspection time, issues that threaten the structural integrity of the balcony should be filed with the building's managing agent. Clean and power wash your concrete balcony once a year to reduce many problems. Consider getting cathodic protection to your concrete balcony if you patch it frequently. This is a method of placing a low-voltage current on the concrete that prevents rust and corrosion.