Brick can come in a variety of forms and be used in many applications of construction. Whether a form of brick is used in house construction be it a retaining wall, chimney, pillars, the house itself, etc., it should be sealed to lock out moisture. Penetrating moisture can deteriorate the brick making it brittle. It can also lead to unsightly problems like efflorescence, fading, discoloration, mold, mildew, or algae. Sealing the brick with a quality brick sealer will provide a protective coat of armor against these contaminants and help to prolong the longevity of the brick.
Prior to sealing brick of any type the surface first needs to be cleaned. Use a quality brick cleaner to breakup dirt and grime. Using a pressure washer, clean the area of the bricks including the mortar joints to remove discoloring dirt, mold, mildew, and grime. If the bricks are suffering from salt leakage be sure to use efflorescence cleaner. If you do not have access to a pressure washer, use brick cleaner and warm water and scrub the brick with a stiff brush. After cleaning allow the brick to dry for a day or two.