How to Apply Stucco to Block

Installing stucco can be a messy process.

Many people find the appearance of unfinished concrete block walls unappealing. Concrete blocks are commonly used in construction for their durability, low cost and ease of use, but bare concrete blocks also allow moisture to seep in. One way to improve the appearance of a block wall is to finish it in stucco. Stucco is a durable material in its own right, and a stucco wall can improve the appearance of a building dramatically.

Things You'll Need

• Pressure washer
• Stucco mix
• Water
• Hawk
• Stucco trowel
• Sponge trowel
• Scarifier
• Nails
• Hammer
• 2-by-2 foot board, 12 inches long

Instructions

1. Spray the concrete block walls with a pressure washer to remove dirt and dampen the surface of the blocks. This will help prevent moisture from being drawn out of the stucco.

2. Mix a batch of brown stucco, following the instructions on the package.

3. Load some of the stucco onto a hawk. This is a metal tray with a handle perpendicular to the surface of the tray.

4. Scoop stucco from the hawk onto the stucco trowel.

5. Spread the stucco onto the wall by starting at the bottom of the wall and pressing the stucco against the wall with the trowel. Begin at a 45 degree angle and lower it to a 30 degree angle as you move up along the wall. Apply a layer 3/8-inch thick.

6. Finish applying the scratch coat to the entire wall. Allow the stucco to start hardening.

7. Run over the scratch coat using swirling motions with a sponge trowel. This will help prevent the stucco from cracking as it hardens.

8. Scratch grooves into the surface of the stucco. You can use a tool called a scarifier, or drive nails one inch apart into a 12-inch long 2-by-2 board.

9. Mix a batch of the finish coat of stucco, following the instructions on the packaging.

10. Apply the finish coat of the stucco onto the wall, using the same process that you used for the scratch coat. This coat should be 1/8-inch thick. Add texture to the finish if desired, or leave the surface smooth.

11. Spray the stucco with water mist every few days during the 6 to 8 weeks it takes to cure the stucco.

Tips & Warnings

• You can add pigment to the top coat of stucco to give it a different color. Just use the same amount of pigment in each batch of stucco to keep the color even throughout the surface of the wall.

References

• Stucco Guru: Cement Plaster Over Concrete Block Walls
• Ask the Builder: Cement Stucco Foundation Finish
• Custom Patio Designs: Apply Stucco