How to Repair Stucco

Figure 1 - House with a stucco veneer

The biggest disadvantage to stucco is that it has no elasticity, so as buildings settle or shift, especially new construction; the stucco has a tendency to produce cracks, some hairline but others can be as much as a 1/4 inch wide.

Repairing Cracks in Stucco:

One of the worst things that a homeowner can do is to make his stucco house look like a giant interstate road map. This can easily happen if the repairs to cracks in stucco are not done properly.

The first step in repairing cracks in stucco is to identify those cracks that need to be filled and those that will be covered and sealed with a fresh coat of paint.

Hairline cracks, those that are the width of a piece of paper or less do not and should not be filled. A quality exterior stucco paint will fill those voids.

Cracks which are slightly bigger than a hairline crack and up to a 1/4 inch wide should be filled using a paintable exterior elastomeric latex sealant or caulk.

1. Remove any loose pieces of stucco, but be careful that the tool you use does not actually widen the crack. A good industrial vacuum with a brush attachment usually works well, although in some cases you may have to lift the vacuum or buy a longer hose in order to reach cracks that are higher up.
2. Wash off any dirt and grime from around the crack.

Note: This is a common home handymen mistake. Sealants and caulks of any type will not adhere to dirt and grime. Washing the area to be repaired is an important step in ensuring that the repair will last and actually seal the crack in the stucco.

3. Using a caulking gun place the tip of the tube of elastomeric latex sealant against the crack and squeeze the trigger while moving the tube up, down or across in order to fill and seal the crack.
4. Use your finger (wet it first) and smooth the sealant. You want the sealant to be level with the stucco, so do not press to hard with your finger or you will inadvertently make a slight cove in the sealant which will make the repair more noticeable. A lightly damp sponge can be used along the filled crack to remove any excess sealant.
5. Before the sealant sets, place some very fine sand on the palm of your hand and blow it onto the still wet caulking. This will help to create a texture on the sealant that is similar to the texture of the stucco aiding the repair to blend into the current stucco and making the repaired crack far less noticeable especially once the completed repair is painted.

Repairing Wider Cracks & Missing Pieces of Stucco:

Note: Wide cracks and pieces of stucco that fall out could be the sign of a foundation problem. It could also be an indication that the original stucco was not installed properly. If your home is new construction you should contact the builder for a thorough investigation of the property.

Cracks in stucco that are wider than a 1/4 inch or missing pieces of stucco should be repaired using an exterior latex stucco patching compound. Exterior latex stucco patching compound is available at most of the big box home improvement retailers or building supply stores.

Note: It is important to precisely follow the mixing instructions that the manufacture of the specific exterior latex stucco patching compound provides with their product. Changing the amount of water used, a little more or a little less can have a dramatic effect on the holding strength of the repair.

1. Remove any loose pieces of stucco that are on the edge or embedded in the crack. A good industrial vacuum with a brush attachment usually works well, although in some cases you may have to lift the vacuum or buy a longer hose in order to reach cracks that are higher up.
2. Wash off any dirt and grime from around the crack.

Note: This is a common home handymen mistake. The exterior latex stucco patching compound will not adhere to dirt and grime. Washing the area to be repaired is an important step in ensuring that the repair will last and actually seal the crack or repair the missing piece in the stucco.

3. Fill the area to be repaired. A putty knife works well to force the compound into the crack or gouged area.

Note: Although putty knives and scrapers look similar, they are not the same tool. A putty knife has flex in the blade and a scraper does not.

4. Once the area is filled, mix a small quantity of the exterior latex stucco patching compound to the consistency of pancake batter. Dip the end of a paintbrush in this mixture. Place your hand between the wall and the paintbrush and slap the handle of the paintbrush against your hand. This will cause the mixture to splatter over the repaired crack or gouge which will aid in blending the repaired area into the older stucco.

Note: If your stucco texture is flat, wait for the splattered stucco to become slightly firm and smooth the excess splattering using a putty knife until you reach the desired effect.

Note: Some exterior stucco is installed using swirls and other patterns as part of the finished coat. It takes expertise to recreate these types of patterns. If you want to attempt to repair these patterned stucco’s on your own, stucco a piece of plywood and practice making the desired pattern. Some patterns are made with trowels while others use small whisk brooms and/or sponges.