| Nothing says “Southwest” like a white stucco finish. The very glimpse of stucco, whether a straight finish or a decorative pattern, makes one think of the sun and hot climes. And although stucco finished homes just became popular in twentieth century the practice goes back to the time of the ancient Greeks. The elaborate wall renderings of the ancient Greeks and Romans were painted on hard plaster composed of gypsum, marble dust and glue. Marble dust compounds could be molded into decorative shapes, polished to a sheen or painted. Stucco techniques improved during the Italian Renaissance. |
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| Down through history, stucco was made of lime, sand and water. Today, stucco is a mixture of Portland cement and water. As well, lime is often added to decrease the rigid properties of modern stucco and sometimes additives such as acrylics and glass fibers are added for strength and malleability. This is usually done with what is considered a "one coat" stucco system—as opposed to the traditional 3-coat method. |
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| Many homes built after World War II used compounds that resembled stucco but had slightly differing ingredients. For example, some siding techniques used foam insulation board or cement panels secured to the walls with screws and then coated with a light layer of stucco compound. There are noticeable differences as walls made of synthetic stucco are lighter easily damaged while real stucco is heavy and will resist strikes and bumps. Also, genuine stucco can be used in wet areas because, when wet, it will dry easily without damage to the structure. |
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| Applying Stucco: Brick and Concrete Surfaces |
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| The application of stucco is quite straight forward. To apply stucco to an existing brick, block or concrete wall a concrete bonding agent is brushed on the wall. When the wall has been dried a “scratch coat“ of 1/4 to 1/2 inch layer of mortar is troweled directly to the hard surface. After the mortar has set it is scratched with a corn broom to a depth of 1/8" and allowed to harden for between 36 and 48 hours, periodically misting the surface to keep it moist. |
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| After the curing period has passed, a finish coat can be applied. The finish coat will be between 1/8" to 1/4" thick. The finish coat can be finished to the desired texture, then allowed to cure for another 36 to 48 hours, with periodic misting to keep the surface moist. |
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| Applying Stucco: Wood Wall |
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| The procedure for applying stucco to a wooden surface differs in that you first apply 15-pound roofing felt over the structure. After the felt has been installed, 17-gauge metal screen is applied on top with galvanized roofing nails. The scratch coat is then applied and forced through the screen which will anchor the stucco. Allow the scratch coat to harden slightly before proceeding to scratch the surface with a corn broom or leaf rake. This coating should be allowed to cure for between 39 and 48 hours. Keep the surface wet with a fine spray from a garden hose so that it will not fry too fast and crack. |
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| Now it's time for the final coat which should be troweled on to a depth of between 1/8” and 1/4”This is the stage where color pigment can be added and/or ornamental designs can be added. As with the scratch coat, do not let it dry out too quickly by using a fine spray from a hose. If you are going to paint the surface you must wait at least 6 weeks and use a paint that is made for this type of surface. |
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| The Story of EIFS |
| Exterior Insulation and Finish Systems refers to a synthetic stucco finish that became popular after World War II when Europeans had to use “quick fixes” on bomb-damaged structures built of stone, concrete, brick, or other similar, durable materials. It became popular in North America in the 1980's on commercial buildings and wood-framed homes because of the R-Value of the foam insulation that sheathes the structure. |
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| EIFS is Multi-Layered |
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| 1) Inside Layer: Foam insulation board is attached to the inner surface with either glue or special screws. |
| 2) Mid Layer: A cement mixture is adhered to the foam and fiberglass mesh is added. |
| 3) Finish Coat: Just like you'd have with traditional stucco. |
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| Europeans build mainly with brick and masonry so their EIFS works great for them. However, in North America the backing is usually wood, OSB or a gypsum board. Without a moisture shield over the backing, moisture can leak in from cracks and fissures around windows and door frames causing damage to the underlying surface. This has caused EIFS houses to silently deteriorate virtually unnoticed. |
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| Another concern with EIFS systems in North America is finding a contractor who knows how to correctly install it. It is not easy to install and some contractors and appliers ignored the manufacturers’ written instructions. Some of these shortcuts added to the risk of moisture leaks. What transpired was a slurry of lawsuits resulting in rebates to homeowners and the outright banning of EIFS in some areas. |
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| As well, written disclosure of EIFS is required in many counties when a house applied with the technique has been sold. |
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| There have been fewer problems with EIFS used over solid bases such as concrete or masonry because these substrates are very stable and are not subject to rot or corrosion. |
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