How to: Stucco Corner Beads
Stucco has been used for thousands of years, dating back to ancient Greece. This extremely durable material is capable of withstanding years of weather encountered by building exteriors. However, it is not a material that expands and contracts easily; therefore, measures must be taken to relieve stress and prevent cracking. The stucco corner bead was designed to help facilitate expansion and contraction, as well as protect the corner from damage, and is applied to either the inside or the outside corner where two stucco walls meet.
Inspect and prepare the surface to be stuccoed. Look for any cracks or other damage to the corner. Any damage should be repaired before the corner bead is applied. Make sure the corner is clean of any dirt, paint, mold, or other substance that could prevent the stucco from adhering to the surface. This is especially important for older structures being stuccoed. Oftentimes, power washing is sufficient to remove surface debris; however, sanding or sand blasting may be needed to ensure a clean surface.
Measure and cut the stucco corner bead. Carefully measure the length of the corner and transfer the measurement to the corner bead, with a pencil. Use a carpenter's square to ensure your line is perpendicular to the length of the corner bead. Cut the corner bead with the snips.
Affix the corner bead to the corner. Hammer non-corrosive nails into the corner bead, ensuring it tightly wraps around the corner. Countersink the nails so they are just below the surface of the corner. Nails should be spaced 8 to 10 inches apart on each side of the corner bead.
Mist the wall. As stucco adheres better to damp surfaces, mist the corner bead and the adjoining wall sections, with water. Do not get these areas sopping wet. A light mist is all you need. If you use a garden hose, do not over-wet the area.
Apply stucco base coat. Load stucco onto the hawk and then the trowel. Hold the trowel at a 45-degree angle and apply the stucco using a sweeping motion, working from the bottom of the corner up. Slowly adjust the angle of your trowel to approximately 30 degrees. Use enough force to press the stucco into the holes of the corner bead. The base coat should be evenly applied and approximately 3/8-inch thick. Use the inner or outer angular trowel to finish the corner.
Float the base coat. Once the sheen of the stucco has gone, but before the stucco has dried too much, use a swirling motion to float the surface with the mason's float. Floating reduces the stucco's shrinkage, which helps prevent cracking as it cures. Let the base coat dry overnight.
Apply the finish coat and texture. Using the same sweeping motion as the base coat, the finish coat should be between 1/8- and 1/4-inch thick. There are several methods for applying texture to the finish coat. The texture may be applied to the finish coat directly, or a special finish material may be added to the finish coat, depending on the desired finished look.
Things You Will Need
- Corner bead
- Non-corrosive nails
- Measuring tape
- Carpenter's square
- Stucco hawk
- Angular stucco trowel, outer or inner
- Mason's float
- Misting bottle (water or garden hose with misting nozzle)
- Texture tool
- Use a plastic stucco corner bead, in place of metal, to prevent rusting from underneath the stucco, as the stucco absorbs moisture.
- A cubic foot of stucco covers approximately 17 square feet of surface.
- Texturing tools can be as simple as a brush or a sponge float.
- Always wear eye protection when cutting the corner bead and when applying the stucco.
- Due to the caustic nature of the lime in the stucco, always wear work gloves when applying stucco.
- Do not apply stucco in extreme temperatures. Stucco should be applied in mild weather, between 50 to 70 degrees Fahrenheit.
- Do not over trowel your stucco, as it can prevent it from adhering.