Exterior walls are generally made from concrete to prevent water from entering the home. The thick, durable material can withstand the ravages of storms and flooding. Excessive moisture build-up on the wall can cause cracks to appear, however, letting water into the home. It may be necessary to patch the material to prevent water from creating further damage. Before repairing, find the source of the excess water seepage and stop it to prevent further cracking of the wall.
Clean out the crack to remove any loose debris. Scrub the hole with water and a stiff brush.
Pour hydraulic cement into one side of a wheelbarrow. Pour water into the other end. Mix the batch of hydraulic cement together with the water in the wheelbarrow until it has a thick consistency. Use the mixing instructions on the side of the bag for the correct water amounts.
Put on plastic gloves. Pack the hydraulic cement into the wall. Add rock to the crack if it is large to keep the hydraulic cement from coming out of the crack.
Buff the hydraulic cement with a cement grinder to even the cement with the wall. Paint if necessary.