CLEANING AND CARE OF STUCCO WALLS
Portland cement plaster walls, frequently called "stucco", provide a decorative and protective covering over a weather barrier of treated building paper or asphalt-saturated felt. Cement plaster has the desirable attributes of being fireproof; tough and weather resistant; unaffected by decay (as is wood), or by termites or fungus; and it doesn't need paint for protective reasons. Paint may be applied for the cosmetic purpose of freshening the surface. The best paint to use to refresh the color of stucco is cement-based stucco paint, because of its natural affinity for cement plaster.
Only minimal care is needed to keep stucco attractive for many decades. The most important item of care is periodic washing of soffits and walls, as should be done to any building constructed of wood, masonry, steel or other material. This paper will provide some suggestions regarding trouble-free care and cleaning of a stucco building.
The building should be washed in the same manner and pattern as with buildings constructed of any other material; that is, the walls must be wet from the BOTTOM TO THE TOP. One should never start hosing any wait at the top, until the bottom and all wall area above the base of the wall have been wet thoroughly, to overcome absorption. The purpose of that method of treatment is to prevent dirty water from being sucked or absorbed into the wall below. A hose nozzle with constricted opening, a jet nozzle, cleans very effectively when attached to the end of a garden hose. That type of nozzle is available at most hardware stores. The nozzle should not be held too close to the roof or wall, because a jet stream develops extremely high pressure, and may affect the surface if held too closely to the roof or wall. One should only stand as close to a wall as is necessary to wash down accumulated dirt. The roof and window sills should be washed also, after all wall surfaces have been thoroughly wet.
The three basic steps employed to wash a wall are:
- Saturate the wall, starting at the base of the wall, and wetting upward on the wall, rather than downward from the top.
- Direct a firm stream of water against the lower portion of the roof, and the top of the wall, to loosen and wash down dirt.
- Flush the dirty water down the wall to the base with a follow-through stream of water, to wash dirt completely away from the wall.
POSSIBLE REPAIR OF DAMAGE
If the plaster has been chipped, as might happen at the corner of a building where an automobile, wheelbarrow, wooden plank or other heavy object might have struck the wall, the chipped area can be titled. That is one of the many advantages of cement plaster. If the damaged area is extensive in size, or if matching an existing texture is important, one may look in the yellow pages of the phone book for a plastering contractor who will take care of the problem. If a small chipped area or hole is the only problem, the homeowner can patch the opening if he or she is handy with tools. One can purchase dry, pre-mixed plaster mortar, or dry, manufactured colored stucco from many building material dealers, lumber yards, hardware stores and stucco manufacturers. Pre-mixed material serves well for patching holes, because only the addition of water is required for use. Only enough water should be added to the dry powder to produce a dough-like mixture. That putty-like mixture of cementitious powder and water should then be pressed into the cleaned opening, and dressed to match the texture of surrounding plaster. A plastic pan, sheet of plywood or metal, or a bucket will serve well as a mixing vessel. A crater should be formed in the dry powder, and the water poured into the crater. The material is to be stirred and mixed as water is added, until the entire mass is homogeneous, and carries sufficient water to produce a workable mixture. Avoid the addition of excessive water, or shrinkage of the patch may occur. The patching plaster may be placed in the hole with a cement trowel or a small brick mason's trowel. The hole is to be filled to the full depth of existing plaster. The surface is to receive whatever treatment is necessary to achieve texture like that on the wall surrounding the patched opening. If the surface of existing plaster has a sandy or grainy appearance, called a "sand float finish" in the plastering trade, the use of a sponge-rubber float can dress the surface to affect duplication of existing texture.
Normally, when the owner elects to re-paint the surface of a plastered exterior wall, a coating of stucco paint, often called cement paint, is used. Stucco paint is a cementitious mixture manufactured in a manner similar to the stucco that was already on the wall.
To prepare the dry stucco powder for use as paint, simply add water to the powder to obtain a creamy consistency, and apply the stucco paint with a heavy fiber brush, often called a Tampico brush. In mixing, be advised by the instructions of the manufacturer of the dry stucco powder. Stucco paint may be obtained at any stucco manufacturer, and from some building material dealers and lumber yards. Stucco paint is available in a range of colors. Mixing and application instructions may be printed on the package of stucco paint, or supplied with the bag. If not, one may write or call the nearest stucco manufacturer for directions, or the Stucco Manufacturers -Association in Van Nuys, California.
If the plaster wall has had oil-based or latex paint applied, and the home owner desires to apply cement-based stucco paint, a coating of good bonding agent must be applied over the old paint, prior to re-painting with cementitious paint. Repainting with any type or kind of paint over existing paint would be done ONLY if the old paint is in good condition, and well-bonded to the wall. If the old paint is peeling or otherwise unstable, it must be removed prior to application of ANY new coating, just as is the case when re-painting wood, steel, or any other surface.
To prepare a wall for re-painting, garden soil adjacent to the wall must be removed to a depth of at least three or four inches, so that the new coating can be applied below grade. The soil should not be replaced until the paint has dried. Next, all loose dirt must be washed from the surface, in the manner described earlier.
After most of the wash water has dried from the wall, it is permissible to start brushing stucco paint onto the wall. If the ground is soft and wet, as it may be from washing the wall, a wide board should be placed underneath the ladder, for safe working, unless the ladder will rest on concrete. It is good practice that stucco paint be applied to a SLIGHTLY damp wall, with no free moisture present on the surface, because that condition aids development of good bond of the cementitious paint to the cement plaster. The paint should be applied sufficiently thick that uniform color will be achieved over the entire wall surface.