How to Patch Exterior Stucco?

Stucco is a creative design element for the exterior of many homes in Southern California. Stucco is a long lasting siding material, and it offers protection and durability. Stucco is similar to cement and it is made of sandaggregate, a a cement binding agent, and water. Stucco is applied in a wet condition, and it becomes very hard as it dries by the process of hydration. If installed properly and allowed to hydrate properly (not allowed to dry too quickly)  stucco can look great on your home.

Due to water infiltration, foundation settlement, wood framing shrinkage, earthquake or improper curing, stucco can crack and spall thus losing some of its aesthetic appeal and protection of the underlying building wrap.  It is possible to fix the aesthetic problem with proper patching. Following is a brief instruction how to patch your exterior stucco.

Take a Look of the Crack:

If the crack is just a hairline (see caulking below). If it is larger then: using a strong putty knife; open the crack into a V shape. This gets rid of any loose material on the edges and provides a “key'” for the patch material to bond.

Patch the Small Cracks First:

If you find any small, thin, hairline cracks then use a water soluble elastomeric caulk and smear it into the surface with your fingers and then wipe down with a wet rag to preserve the surrounding texture. SUPER IMPORTANT: go over these cracks after caulking with a small about of cement stucco to better match the surrounding surface. and then spot prime. If you paint directly over the caulk, it will be seen as a shiney line where the caulk makes the paint “flash”

Clean the Larger Cracks:

In case you find larger cracks, you need to clean them first. As noted above: using a strong putty knife; open the crack into a V shape. This gets rid of any loose material on the edges and provides a “key'” for the patch material to bond. Then use a wire brush or a similar object to clean out larger cracks. You can soak the area with a hose in order to remove any dirt and debris. Cleaning the larger cracks on the stucco ensures that your patch job is durable enough to last long.

Patching the Stucco:

There are many different grades of stucco based on the size of the aggregate used. If you have a fairly standard surface, you can purchase fortified stucco patch that works in most situations. You will need the dry mix plus some masonry glue. Paint the masonry glue in the crack and then mix up a batch of patch. Using a putty knife, apply into the crack. Using a sponge trowel you can “float” the surfaces smooth using a bit of water. This completes the patch unless you have a texture on top….this is where you call a pro as the textures take years of experience to perfect…especially in patching.