Stucco 101

Hardcoat versus Synthetic (EIFS) Stucco
“Hardcoat” Stucco has been in existence for more than a thousand years! A cement or cement-like substance, it was used to coat the exterior and/or interior walls of ancient Roman villas, Swiss cottages, and European castles over the centuries. It is porous, making it an idea substance to decorate with colors and motifs. Hardcoat Stucco has been in the United States since before the Revolution, coating the exterior of stone and brick buildings to give them a smooth, upscale look. Synthetic Stucco was invented after World War II and used to recreate damaged/ destroyed European buildings.

The “skin” of traditional Hardcoat Stucco is a mix of sand, Portland cement, a little lime and water in three layers. Underneath that is a variety of substraints such as OSB or plywood, a waterproof barrier, lathe/mesh, and flashings. Hardcoat has numerous advantages. It can achieve compressive strengths in excess of 3,000 pounds per square inch. Ladders, baseballs, and rocks will rarely dent it. If you have a talented plasterer, you have unlimited surface texture possibilities. Furthermore, if you use time tested installation methods, you can create a weather tight barrier to
wind-driven rain, snow, and ice. As for its disadvantages, cement stucco is a rigid material. If the wood framing beneath it shrinks or if the house settles, the cement stucco may crack. Hairline cracks are the hallmark of Hardcoat Stucco.

Synthetic Stucco or EIFS (Exterior Insulating Finishing System) was introduced to the US in 1969 by Dryvit Systems, Inc. because of its exceptional insulating qualities, durability, and curb appeal. EIFS’ multi-layered systems typically consist of a polystyrene-based insulation board, a base coat reinforced by glass fiber mesh, and an acrylic polymer finish coat. (link to www.parex/basics.html and pickup the layering substrate picture)

Although it resembles Hardcoat Stucco, EIFS has far more flexibility and can be fashioned into a variety of architectural shapes such as decorative trims, archways, and window and door trim accents.

EIFS outperforms most other exterior wall claddings such as brick and siding in insulating against the winter cold and the summer heat. Click here to read more about this energy efficiency. By design, EIFS is a moisture barrier system, but as with any exterior cladding, moisture can seep behind the system at windows, doors and other penetrations that are not properly sealed or in good condition.

Even more important, EIFS finish-coat is designed to resist dirt, mildew and mold, and when dirt does collect on the surface, it can easily be washed off with a hose or a hose in combination with a soft bristle brush. Since it is colorfast (although it may fade a bit throughout the years), it does not require painting. If surface is scratched, the same color appears beneath the abrasion.

Unlike Hardcoat, EIFS is crack-resistant and will take most building settling or movement.

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Why is Stucco a “Problem”?
If the stucco system was not terminated approximately 6 inches above ground, the system allows for termites to enter the home. Many Atlanta stucco homes today have had the stucco modified so it no longer terminates at the ground level, eliminating this problem. On these modified homes, only the colorful acrylic top coat and mesh extends the exterior cladding to the ground level; the underboard has been removed. This modification, when done well, is hardly noticeable.

If the stucco system was installed correctly, but proper maintenance of the other elements (windows, doors, siding, trimwork, etc) has been ignored, the moisture-barrier properties of the stucco system can work against the homeowner. For instance, if window sills have been allowed to rot and pass moisture behind the stucco cladding, the moisture barrier does not allow for quick evaporation of the dampness, especially for EIFS. Continued exposure to moisture over time can deteriorate the wall structure of a home and create a situation conducive to mold growth. Eliminating leaks through the sealing of unlike cladding materials and continued maintenance of windows, doors, trim, roof, gutters, and siding, can eliminate this problem in our area. EIFS homes properly maintained and sealed are not “problems.”

Hardcoat Stucco homes are more forgiving of minor moisture intrusion. In addition, being a cement product, like your sidewalk and driveway, when it becomes wet, it allows moisture to evaporate back out.

	Deferred maintenance on the exterior of any home – whether clad in brick, stucco or siding—can create a compromised wall structure if ignored for long. Properly maintained homes of any type are not “problems.” Look to the right for two examples of significant termite and mold damage on a brick home.
	back to top^	Water Intrusion Damages All Homes—Brick, Too!	Significant Termite and Water Damage

What about Mold?
A poorly maintained home – stucco, brick or siding – can harbor mold. Mold is a form of fungus, and as a living organism, it requires food to sustain it. It must have moisture and organic material found in homes and buildings such as the wood and paper. Mold proliferates in moist, warm environments. There are hundreds of species of mold found in the United States that are not harmful to humans. However, certain molds can cause a variety of illnesses in humans. Three molds which are known to be harmful to humans are: Aspergillus, Penicillium, and Stachybotrys chartarum. These forms are commonly known as toxic molds.

The following is a list of steps to help you minimize toxic mold growth:

• Most importantly, stop water intrusion. Repair all leaks.
• After a leak, remove all water or mold damaged wood, wallpaper, carpet etc. (Depending on the type of mold and the extent of the infestation, this may need to be performed by a mold remediation professional).
• Keep all exterior surfaces of the home properly sealed (and painted, if applicable).
• Control your home's humidity via an air conditioner and/or dehumidifier (keep between 40 and 50 percent)
• Be sure the home has adequate ventilation. Is the HVAC operating properly? Can you increase air flow by rearranging furniture? Is the clothes dryer properly vented to the outside?

If concerned, you can arrange to have your home properly tested for mold. Click here to get a list of recommended companies that test for mold.

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What about Settlements and Pending Litigation?

In 2002-03, Dryvit Systems Inc. came to a class-action suit settlement (link to www.stuccosettlement.com) and owners had to file for benefits before June 2004. There have not been any settlement agreements since then.

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What’s New for Stucco?

Despite years of “bad press,” the commercial market continues to clad 30% of their new construction in EIFs due to its insulating ability and its beauty/versatility.

Residential builders are beginning to use newer EIFS systems which include a drainage arrangement to help trapped moisture to escape easily. One contemporary EIFS system, the DRYVIT Residential MD System PS 440 is engineered to drain moisture away to the exterior. A drainage plane is installed between secondary weather barrier and the insulation board. Water is allowed to “weep” to the exterior. (By the way, most Georgia County Codes now call for brick homes to have similar “weep hole” drainage systems to avoid trapping moisture behind the brick!)

New EIFs outer layer products have improved dirt pickup resistance and proven mildew growth resistance.

Many manufacturers are now offering builders and their buyers 30-year transferable homeowner warranty programs for one- and two-family homes.

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