Stucco looks great and provides a protective barrier for masonry surfaces. However, improperly applied, it will pop off and expose the material it’s designed to hide. When a homeowner started noticing his foundation stucco cracking, he called mason Mark McCullough for help.
Steps for Repairing Cracked Foundation Stucco
- Start by using the shovel to remove the dirt and grass around the foundation. Pull back about 6 to 8 inches of soil to expose the foundation.
- Tap along the face of the stucco with the chipping hammer and listen for any hollow sounds. This indicates that there wasn’t enough bonding agent used. Chip away the loose stucco.
- Use the rubbing tool to knock any of the high spots of the foundation down. Rub the tool back and forth to sand the high spots down, and then wet the foundation to control dust and to keep it from removing too much moisture from the new stucco.
- If there is any existing damage or missing concrete, repair it now. Use the masonry trowel to pack concrete mix into the damaged area and shape it to match the foundation. Give it some time to set while you prepare the rest of the stucco.
- Use the pump sprayer to apply the bonding agent to the foundation. Start at the bottom and work upward. Use a masonry brush to ensure complete coverage, again, working from the bottom to the top.
- Mix stucco using the following formula: 90 pounds of Portland cement, 4 shovel fulls of lyme, and 20 to 25 shovel fulls of sand (adjusting to match the foundation). This is a lot of material, so you can cut the formula in half if needed, or purchase pre-made stucco mix.
- Use the steel trowels to apply the stucco. Apply stucco to the trowel, press it against the bottom of the foundation, and drag it upward. Be sure to push it into the existing stucco and over top. This will get cleaned up later and create a seamless finish.
- Use the edge of a trowel and trace a light grid pattern into the wet stucco. This will provide more grip for the finish coat.
- After the scratch coat cures, apply the finish coat over top.
- Fill a bucket of water and use the sponge float to mimic the existing texture. Use a light circular motion to move the wet material to where it needs to be and blend any transitions between the existing stucco and the finish coat. Rinse the sponge float as needed.
- Lightly water the surface a few times a day for the next two days. After that, allow the stucco to cure completely and enjoy your repaired foundation.
Resources
For Mark’s stucco mix, he used:
But for a homeowner’s smaller project, Mark recommends a pre-mixed stucco bag. Use a mortar tub to mix the ingredients together.
Mark removed any loose stucco with a brick hammer. Then they took a 20-grit rub brick to smooth down the face of the foundation.
Using a multi-purpose lawn and garden pump sprayer, a masonry admix and bonding agent was sprayed onto the foundation before the stucco mix was added. A masonry brush was used to spread out the glue.
To spread the stucco mix, steel trowels were used. For this small work area, they used a 12”x4” finishing trowel and an 8”x3” finishing trowel. And a London brick trowel was used to pick up the mix and add it to the finishing trowels. Mark also used a margin trowel to shape the corner of the foundation.
To match the consistency of the existing stucco, a few different tools can be used with a bucket of water. A fine rubber float or a foam hand float could work. But Mark finds that a normal multi-purpose sponge can usually get the job done.
