How to Cover a CMU Wall With Stucco

Stucco, a weather-resistant, plaster-like material forms a lasting covering when applied to exterior buildings. The weatherproofing material not only provides protection from snow and rain, but also from fire to some extent. You can install it on rough surfaces, including concrete masonry units. Made from concrete, CMU walls last for a long time. Covering your CMU wall with stucco enhances its appearance and increases a building's curb value.

Paint scrapper
Power washer
3/8-inch wood lath
Saw
Hammer
Masonry nails
Stucco
Mortar mixer
Hawk
Trowel
Straightedge
Nail puller
Wooden float
Sponge, rake or sharp tool

Instructions

- 1
  Inspect the CMU wall for cracks, holes or other defects. Remove flaking paint from the wall with a paint scrapper, and then power wash it to remove residue, accumulated dirt and mold. You need a smooth, clean surface so that the stucco adheres to it.
- 2
  Measure and cut strips of 3/8-inch wood lath to cover the width of the wall using a saw. Secure the horizontal strips to the upper and lower sections of the wall using masonry nails. You may need additional strips along the middle of a tall wall.
- 3
  Prepare the stucco for the base coat in the mixer following label directions, until it possesses the consistency of softened butter. Lightly mist the CMU wall with a sprayer before applying the stucco to it.
- 4
  Load the prepared base coat onto the trowel using a hawk. Hold the trowel at a 45-degree angle when applying stucco over the wall and gradually set it at 30 degrees. Apply this coat in a sweeping motion over the wall, until it is completely covered. Ensure that this coat is no thicker than 3/8 inches.
- 5
  Level the surface of the applied base coat on the wall using a straightedge. Set the ends of the straightedge against the wood lath you attached to the wall, and gradually move it up and down to smooth the surface of the stucco and remove excess.
- 6
  Pull out the nails securing the lath to the wall using a nail puller. Do this carefully to avoid damaging the stucco. Rub the wall with a wooden float, moving it in circular motions along the surface, to prevent the stucco from shrinking or cracking as it cures.
- 7
  Prepare another batch and apply it over the wall the next day. Using the trowel, apply this coat of stucco over the CMU wall the same way as the previous coat. However, make this coat no thicker than 1/4 inch thick.
- 8
  Texture the wall using a sponge, rake, trowel or any tool of your choice to finish it. Depending on your personal aesthetic preference, create swirls, lines or patterns on the stucco, or leave it as it is.
- 9
  Allow it to cure thoroughly for the time specified on the label’s directions.

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