Stucco made with Portland cement was an exterior finish of choice for many houses built in the 1920s. (Stucco prior to 1900 normally was lime-based.) The cementitious material could be tinted various colors, and given a textured finish that might be smooth or coarse depending on the aggregate in the mix: sand, pebbles, or mica. Stucco typically is applied over wood lath or metal mesh, although the substrate might be masonry.

Despite its durability, even Portland-cement stucco can deteriorate. Spalling, bulging, and cracks need to be addressed to maintain the integrity of a stuccoed exterior. Before beginning a patching project, watch the weather. Overcast (not rainy) days are your friend. Too much sun, or harsh weather, may prevent the mortar from curing correctly. For further protection from the elements, consider covering patched areas with a tarp.

Stucco Types

Because of its durability, fire resistance, and low-maintenance qualities, stucco has long been used as an exterior finish, starting with the Romans and continuing to this day. Two types commonly found on American old houses are lime stucco and Portland-cement stucco. The two are not interchangeable. Lime stucco, flexible and less prone to cracking, is composed of sand, water, and slaked lime as well as an aggregate for texture. Portland cement is a mixture of cement, sand, water, and slaked lime, with the addition of an aggregrate. It, too, is durable and versatile, but hardens more than lime stucco and can be brittle.

For either type of stucco, the texture of the finish coat may come from mix-ins including sand, mica, or pebbles. (Lime stucco often includes animal hair.) The best matches for your original stucco will come from local sources; check local quarries for sand and small pebbles that may blend in. Do test patches until you get a match. Stucco may be painted, but also may be tinted before it is applied.

When repairing stucco, use the type that matches the original. To determine which it is, mix one part muriatic acid with 10 parts water in a lidded glass or plastic, acid-resistant jar, and drop a chip of the stucco into it. Close the lid tightly and shake. Lime stucco dissolves in acid, Portland cement does not. Caution: When working with muriatic acid, wear gloves, goggles, and protective clothing. Work outdoors because of the fumes. Pour the acid into the water, never the reverse.

What causes stucco damage

Water causes most stucco failures. Improper mixing of mortar, bad installation, house settlement, and weather also contribute. Unchecked water dripping where it shouldn’t will cause stucco to delaminate, creating bulges and cracks. Wood lath rots and warps; metal lath corrodes.

Sources of water include rain from overflowing gutters or backsplash, wicking from the ground, leaky plumbing, and vapor migration from inside the house. Find the solution: Repair gutters, drip edges, and flashing; add a vapor barrier; fix leaky plumbing; mitigate the capillary action of groundwater.

Settling is the most common cause of cracks; poor initial installation and seismic activity are others. Investigate to find the reason for cracks that grow or change direction. For foundation problems, a professional assessment may be needed. For hairline or stable cracks, proceed with the repair.

Cracked Brick and Stucco Repair from CDP Stucco

CDP Stucco has repaired cracked stucco for homeowners throughout Florida. If you are unsure if the cracks indicate foundation failure, a representative from CDP Stucco can provide an inspection to give you back peace of mind.

Contact us today for an inspection of your cracked stucco repair! If you are interested in Stucco Installation or Stucco Repair, call the experts at CDP Stucco now at 850-259-2283