Can I Apply Stucco on Outdoor Drywall?

Prepping the Wall

• Exterior drywall and Sheetrock require the use of a wire netting to help the stucco adhere to it. This netting may be plastic or metal and is typically sold as "stucco netting." The openings are about 1/2-inch wide, which allows the initial stucco layer to cling to the wire and the drywall. Stucco netting is sold in large rolls, which may be cut down to the appropriate size with tin snips. Once the stucco netting is cut to fit the wall, it is attached with finishing nails. The stucco netting should not sag in any location and should be tight against the wall.

Mixing the Stucco

• Stucco is a mix of dry components, such as Portland cement, lime, sand and other materials. Rather than mix them yourself, you can simply purchase pre-mixed stucco, which only requires that you add water. There is not much of a difference in price between buying the separate ingredients and mixing them yourself versus buying pre-mixed stucco. It's recommended that you leave homemade stucco to the professionals.

Scratch Layer

• The scratch layer is the first layer of stucco. It can be applied with a special plaster sprayer or with a trowel. Ultimately, you will always need to use a trowel, even if you use the sprayer, because you will need to smooth the stucco plaster out. If you opt for the sprayer, work with a partner -- one person can spray while the other follows with the trowel. Once the stucco is smoothed, scratch it with a plaster rake in a horizontal or crisscross pattern before letting it dry.

Leveling Coat

• The second coat of stucco is typically called the leveling coat or brown coat. It is usually a bit thicker than the scratch coat but can be applied with the same technique, though you must moisten the scratch layer by misting it with water. This is the layer that ensures that the stucco has been applied evenly. Once the stucco is on the wall and smooth, use a plastering float to make this stucco layer perfectly level. This layer may be moist-cured if you are experiencing unusually dry weather -- this involves periodically misting the wall with water so that it doesn't dry too quickly.

Finishing Layer

• As its name suggests, this is the final layer of the stuccoing process. You have a little bit of freedom here because this is where you can create the final texture for your stucco wall. You may opt to continue using stucco, or you can use an acrylic stucco finish. In either case, the finishing layer is when you get to add color and texture to your wall. You may use a trowel or other stucco finishing tools to create patterns of texture, or you can create a smooth surface.