Sand the entire surface of the wall using a sanding buffer with a medium-grain sanding ring. This removes the peeling, chipping latex paint and smooths down areas of roughness. If the paint is not peeling off of the wall, ignore this step.
Vacuum the wall and surrounding areas using a shop vacuum. This removes dust, paint chips and debris from the wall.
Fill a paint tray with waterproof latex paint, then coat a standard-sized paint roller in the paint.
Apply the waterproof latex paint over the entire wall, then allow the paint to dry for eight hours. Apply a second layer of paint if needed, and allow the second layer to dry for an additional eight hours.
Fill a second paint tray with clear waterproof sealant. Coat a paint roller in the clear sealant, then apply the sealant over the painted wall. Allow the sealant to dry for eight hours, then apply a second layer of sealant. Allow the second layer of sealant to dry for another eight hours to ensure that the wall is properly protected from the elements.