If the weather is sunny, store your stucco and sand under a tarp between uses. If they feel warm to the touch, don’t attempt to use either the stucco or the sand.
It is possible to stucco over an open frame, but this results in a less even and less structurally secure wall. If you plan to go this route, drive nails halfway into the studs, spaced out vertically in 5-6 inch (13-15 cm) intervals. String line wire horizontally along the protruding nails. [4] X Research source
Start at the bottom and overlap the paper or felt as you work your way up. While not required by most codes, an air gap between the 2 layers is highly recommended to prevent wall rot. A 3D plastic drainage mat between the 2 barriers is one way to accomplish this. [7] X Research source Using a screen can help prevent cracks from forming in your stucco later on. [8] X Expert Source Nick YahoodainGeneral Contractor Expert Interview. 6 October 2020.
For this project, these 2 materials are not interchangeable. [11] X Research source
Be sure to use only galvanized roofing nails or staples designed for use with stucco. Otherwise, your nails or staples will rust and pull loose. In all exterior stucco applications, you must use G-60 hot-dipped galvanized lath. [13] X Research source Choose lath with at least ¼ inch (6mm) furring, or make up for non-furred lath using furring strips or furring nails. [14] X Research source Without this furring, the stucco will not adhere properly to the lath.
Make the panels as close to square as possible, and no larger than 144 ft2 (13 m2). [16] X Research source
Make sure to use cool water when mixing your stucco, especially if your hose has been sitting in the sun. If the water is hot or warm, it will cause your stucco to dry too quickly. The aggregate in the cement should be clean and well graded.
The first scratch coat should be thick enough to cover your wire grid. You may find it easier to use a hawk for some portions of the application.
You can also use a rotating lawn sprinkler to keep the stucco damp. Keep the sprinkler turned down to a low setting and pull it away from the house enough so that it keeps the surface damp without soaking it.
Colored stucco finishes work best in pastel shades. If the finish is colored, wetting the surface during floating may cause mottling. A fog coat may make the color more even. Many decorative textures are possible when applying this final layer. Judge the appearance from at least 30 feet (9m) back before settling on a look. [22] X Research source
Acid etching. Sandblasting. Bush hammer or roughing machine (for unpainted, smooth surfaces). [24] X Research source Applying a bonding agent, referring to specific product instructions. Do not use a bonding agent over water-soluble paint. [25] X Research source If there is any doubt that the wall can support the stucco, apply the stucco as you would to a stud wall, attaching metal lath and plastering over it.
Delay the job if the next week of weather involves freezing temperature, hot weather (above 90ºF / 32ºC), or high wind. These conditions will interfere with the curing process.
Only add enough water to allow you to trowel the plaster, or it may sag or fail to stick to the wall.
Acid-etched surfaces (among others) may not be quite rough enough for a strong bond with this method. Instead, dash on the scratch coat using a cement gun, or by whipping it on with a fiber brush or whisk broom. This forces out air to create a stronger bond. [29] X Research source Some builders combine the scratch coat and brown coat into one base coat. If you choose to do this, plan on a total stucco thickness of about ⅜ inch (9. 5 mm) for cast concrete, and ½ inch (12. 7 mm) for unit masonry. [30] X Research source Allow about ¼ inch (6. 4 mm) of this thickness for the finish coat. [31] X Research source
The brown coat mix should contain 1 part cement materials and 3 to 5 parts sand. [35] X Research source It may help to compact this layer with a shingle float.
In extremely hot or windy conditions, put up a windbreak and sun shade. You may even need to cover the moistened surface with polyethylene.
If you’re not experienced with applying textured finishes, a texture roller is a great option for achieving high-quality results. Apply the roller evenly over the final coat.
