Before Installation: Surface Requirements
All stucco systems have one thing in common: Stucco eventually cracks! The degree of cracking depends on the quality of the installation and the experience of the installer’s labor and workmanship. Thin or stressed walls can decrease the longevity of a stucco finish. Structural or mechanical stress – like sheet rock being nailed into place, electrical pene
trations being installed, or boxes and outlets are nailed into studs, or saw cutting – can cause cracks in your stucco. A surface must be stable and vapor permeable for the stucco finish to be durable. Sealers used to resist excessive hairline cracking, weathering, or staining must maintain vapor permeability. Trim molding should follow manufacturer recommendations. A grout line of ¼ to ½ inch should be included to absorb thermal expansion and contraction stress. Grout is able to crack and absorb the thermal movement without stressing trim or stone. It may be re-grouted, though this is usually unnecessary. Stucco Finish Options
Old World finish stucco gives a naturally weathered look. This look can be made showing minor cracking, checking, simulated staining and etching. The stone effect finish is usually the desired finish for aerated concrete, foam cast moldings, cornices and trim. Commonly desired appearances range from smooth sand finishes to stone-like or textured looks. When applied correctly, any of these will provide lasting beauty for the life of the structure. Stucco Application Methods
The most popular stucco in the Southwest uses the three coat system: scratch, brown, and finish. This is generally three quarters of an inch thick, sometimes more, and resists weathering. Stucco aggregate can be natural or synthetic, sand, marble, granite or stone. The most common materials are white or gray Portland cement, lime and fine aggregates, combined with water, latex, or acrylic resin. Natural and artificial colorants are used to achieve various colors and shades. Instead of colorants, some techniques use various colors and grades of sand to achieve desired coloration and variance. Shading and mottling techniques do vary yet are all very similar as well. Where desired, one or more shades can be combined as by using various colors of sand or colorants. Some applications require a hopper to broadcast a finish or color, which is then burnished into the wet finish coat with a flat metal trowel. Other applications are broadcast mechanically or tooled and brushed by hand. Any of these techniques yield satisfactory results.
