Sweep the concrete with a broom to remove loose debris and dirt. Apply painter’s tape to surrounding areas that you do not want the waterproofing to get on. If you are waterproofing outdoor concrete steps, lay plastic sheets over nearby landscaping to protect them from the sealer and cleaning solution.
Fill a bucket with 1 gallon of warm water. Add 1 cup of household ammonia to the bucket. Scrub the concrete steps thoroughly with the cleaning solution and a stiff scrub brush. Rinse the steps clean with plain water from a garden hose or with a bucket of water and clean rags. Allow the concrete to dry thoroughly.
Stir the can of sealer with a paint stirrer. Pour the sealer into a paint tray with a liner.
Dip a large paintbrush into the paint tray to absorb a generous amount of waterproofing sealer. Apply a thin, even coat of the sealer to the edges of the steps.
Dip a polyester paint roller into the tray to paint the rest of the steps. The roller will give the steps an even coat of sealer. Saturate the steps with the sealer, smoothing it out with the paint roller. Avoid allowing the sealer to puddle in any areas. Back brush, if necessary, with the paint brush to remove any puddles or roller marks.
Allow the waterproofing sealer to dry completely according to the manufacturer’s instructions. This generally takes a few hours.
Apply a second, thin coat of the sealer to the concrete steps in the same manner as the first application. Avoid walking on the steps for at least 24 hours after the second coat of sealer has been applied.