Stucco 101 FAQs
"Everything you ever
wanted to know now about
The Stucco Manufacturer’s Association of California has the following description of the benefits of Stucco as quite possibly the optimum siding for buildings:
“Aesthetic appeal and versatility of design have for centuries captured the imagination of architects and builders. Portland cement plaster has inspired designers to new levels of artistic expression in a variety of building projects when used alone or in a combination with other traditional building materials such as stone, brick, or wood.”
Versatility of design and aesthetic appeal: Portland cement plaster can be applied to most flat or curved surfaces, inside or outside, in any structure or building lending itself to innovative and creative solutions. Any project can be individualized. Natural beauty: Stucco’s inherent natural beauty has for centuries enhanced structures around the world. It simply looks great on any type of architecture.
The Choice of Builders
Stucco has been the preferred finish of discriminating builders, from lavish villas in Europe to modest abodes of Native Americans. Unlimited textures and colors: The finish possibilities are infinite, smooth to course, interesting variety; it is unique among the decorative finishing materials. It can be used to provide highlights, depth, and continuity. A nearly unlimited palette of colors that never need painting is available to provide a uniform, maintenance-free finish for your most lavish designs. Imagination is the only limitation.
Tough, durable, long lasting
For centuries, stucco has been known for its durability. Tough, long lasting, abuse and impact resistant, its performance in a variety of climates, enduring wet/dry and freeze/thaw cycles and the extreme desert heat, has made stucco the global standard in cladding materials. In addition, stucco’s fire-resistive properties make it a safe covering for your home or business.
Portland cement plaster is the most inexpensive wall finish by far. Its proven long-term value has been time tested and well documented. Stucco is the most durable and long lasting wall finish providing years of maintenance-free beauty. Stucco is also easy and inexpensive to repair. Restucco of existing buildings easily allows change to the appearance of color and texture, giving new character and variety to old buildings. When you see all that stucco has to offer, you realize it is a “hard system to beat.”
Properly installed stucco can last many decades; at least 40-50 years under normal conditions. This long life can be shortened dramatically by certain influences.
Typically, the influence with the greatest impact is moisture intrusion. Of course stucco is designed as a “building envelope” which, by its nature, protects against the rain and other sources of moisture from the outside (like normal overspray from sprinkler systems). In these scenarios, the stucco immediately sheds the bulk of the water, and only minor amounts are absorbed, and that which is absorbed is typically dried out by the sun and breeze – thereby removing the possibility of damage to the stucco system. Unusual and early deterioration of stucco systems almost always takes place when water finds its way inside the building envelope.
Water that enters the system and remains there will be unable to dry out quickly can do serious damage to all components of the stucco system, including wood framing, metal components like lath, and of course the stucco itself.
Properly installed stucco DOES NOT allow liquid water to permeate its thickness – except for areas with extreme cracking that allows water to pass through the cracks (typical minor stucco cracking does NOT provide a path for water).
In most cases the answer is yes. It is likely that a building permit will need to be acquired by your general contractor. In some instances a “lightweight” 2 coat system may be necessary because of structural limitations. All of this can be determined by a reputable architect or builder.
Stucco is water resistant, but not water proof. Moisture can permeate somewhat into the stucco but despite the mistaken belief of certain stucco “experts”, free water or liquid water will not flow through properly installed stucco.
How Then, Does Water Get Inside The Stucco System?
Far and away the most typical source of water intrusion is from roofs, windows, doors, and other penetrations of the stucco. If water enters the interface of those intrusions, this water can end up inside the building envelope, and if unable to promptly exit, can do great damage to the system, and provide a fertile field for mold growth, etc. Water can also enter the system by “wicking up” from the ground in certain instances of improper or obsolete installation, or when site conditions including landscape watering have not been properly managed.
The key to preventing water from entering the stucco system is proper installation in the first place. This means that great care was taken to properly waterproof the structure and all penetrations utilizing all of the latest technologies. In the event of failures after the fact all of the following needs to be considered:
1. Roofs: If water is allowed to enter the system because of roof problems, there is nothing the stucco contractor can do to correct. The roof must be first properly repaired, and then the stucco contractor can review and repair the stucco system as necessary.
2. Windows and doors: If there are leaks near windows and doors, the first step to identifying the problem is to rule out the window itself. Isolated testing can be done to make that determination. Once the window or door has been eliminated, the interface between the window and the stucco should be examined. In this event, the likely failure is the gap between the window and stucco that can sometimes allow water penetration through that gap. In that event appropriate repairs can be made with follow-up testing. In some cases the failure may require windows to be removed and reinstalled but not until other less invasive repair methodologies have been deemed ineffective.
3. All other wall penetrations: everywhere there is an exterior light fixture, electrical outlet, plumbing fixture etc., a potential leak point exists. Water damage in proximity to these items can be caused by gaps or openings associated with those penetrations. Evaluation and repairs of these failures can be performed and the problems can be corrected.
Though liquid water cannot pass through the cement matrix of stucco that has been properly installed, moisture (as opposed to liquid water) can permeate to some degree into this matrix – especially when driven by horizontal winds from the sea. Winds that come from the sea can be salt saturated causing chlorides to enter the matrix allowing the chemical reactions from the chlorides that cause the metal lath and accessories to experience accelerated corrosion, and the cement stucco matrix to deteriorate and lose strength.
Is Stucco A Good Building Envelope Material For Seaside Environments?
Portland cement plaster is suited to virtually every type of climate, whether wet or dry and hot or cold. It is popular in coastal environments because it is unaffected by moisture, but when metal lath is part of the system, there are potential concerns due to the elevated chloride levels in the environment.
In coastal areas, air is literally salty: it carries chlorides. This is an aggressive ion that corrodes metal. Hardened plaster is not affected by chlorides. Typical 3 coat stucco includes metal lath and accessories like corner bead, etc. The combination of galvanized coating and plaster cover protects the metal. However, the metal lath and accessories, despite being galvanized eventually may be subjected to the effects of the chlorides – especially if substantial cracking of the stucco is present. Despite these concerns, you will be hard pressed to find a building envelope material in a seaside environment that is superior to stucco.
What Can Be Done To Reduce Early Deterioration Of Seaside Properties?
Finish coat systems that are acrylic based can be substituted for conventional stucco finish coat. These acrylic based finish coat systems can completely prevent moisture from ever entering the stucco matrix and the result can be a profoundly longer life for the stucco system in these vulnerable areas. Additionally, new components incorporating new technologies can be substituted for the old more vulnerable components are now available. These products include lath that is made of fiberglass, new corner bead and “weep screeds” that are made of vinyl, which is not subject to corrosion or degradation in these environments.
When the existing stucco and its related components are structurally stable and without substantial deterioration, a simple power washing can remove much of the accumulated dirt and organics. This is an inexpensive and quick fix for minor cosmetic issues. Cost ¢¢
• Fog Coat:
When the existing stucco and its related components are structurally stable and without substantial deterioration, but the color has become blotched and faded, a power wash and “Fog Coat” can be applied to greatly improve the look. Fog Coat is a dilute mixture of actual stucco color coat – just like that used for final finish coat on conventional stucco projects. Fogging the surface improves the blotchiness and returns the richness of the original color to the structure. Fog coat can only be used on projects in which the original stucco finish coat was conventional integral color – not
finish, and never painted. Cost $
• Restucco Without Sandblast:
If, and only if, the existing stucco is structurally stable, has never been painted, and has a texture that will promote a good bond, the structure can be restuccoed by using a commercial bonding agent after a thorough power washing. The bond will never be as robust as the bond to a sandblasted surface, but this strategy can achieve an acceptable result when economics play a role in the decision process. Cost $$
• Sandblast And Restucco:
Sandblasting before restucco is ideal because it prepares the surface for a perfect bond with the new stucco. The sandblasting insures the stability of the surface beneath the new stucco, and guarantees the optimum life of the finished product. Cost $$$
• Sandblast Mesh And Restucco:
When a restucco project is going to be a smooth finish and the customer wants to minimize cracking potential, the restucco can be done with the application of fiberglass mesh embedded in the base coat that is applied prior to finish coat. This is the optimum strategy to reduce cracking. This process adds cost to the overall system, but will absolutely improve the resistance to cracking. Cost $$$½
• Restucco with Based Finish Coat:
New technologies in the industry have resulted in new acrylic based finish coat materials that can improve the performance of the stucco system. The material is highly resistant to water penetration and in-fact can be considered an additional moisture barrier of the system. Additionally the material will bridge cracks in the subsurface and flex rather than crack when exposed to minor structure movement. Also, the colors for acrylic finishes are unlimited and can be matched to virtually any color, though as always with stucco, darker colors tend to be a bit more problematic. Acrylic finishes have sometimes been described as “bullet-proof” because of long life that can be expected from these state-of-the-art products. Cost $$$½
• Complete Demolition Of Stucco And Lath:
When the condition of the existing stucco is so poor that the metal lath and accessories along with the old building paper is completely deteriorated, there may be no choice but to completely remove the stucco along with the lath and old building paper. Following that removal, an entirely new stucco project including building paper, lath and stucco must take place. This is an expensive process that is required only when it is determined that there is no other choice. Cost $$$$
Paint can improve the look of old stucco, but we do not recommend painting of stucco. If stucco is painted once, it will have to be repainted again any time the paint begins to fail and thus can create an ongoing maintenance problem that can only be reversed by sandblasting. We prefer keeping the existing conventional color coat looking good by power washing and fog coating.
Sandblasting is a process utilizing a high-velocity stream of ‘aggregate’ and water for the purpose of removing those portions of the existing stucco that have lost structural soundness. The result is to provide a stable base upon which new material can bond.
Sandblasting is the optimum method to prepare the surface for a restucco project. This is because the bond between the new stucco and the old substrate is critical to the long term integrity of the finish. In some cases, where the old stucco or substrate is stable and clean, a bonding material can be used and the restucco can be done without sandblasting, but the bond will never be as robust as with a sandblasted subsurface.
In any remodel or improvement, sandblasting should be performed as early on in the construction process as possible. It should be done prior to the installation of new windows and doors, ideally while the old windows and doors are still in place. Even though all components that could be damaged are masked with plastic and tape prior to blasting, it is still safest to minimize the exposure of sensitive new building components. Also of additional importance, any form of landscaping or hardscape should not be installed prior to sandblasting.
Sandblasting in itself is a destructive and intrusive process and can easily damage unprotected items in its path, when improper care is used. It is imperative that it be done by professionals that will go the extra mile to protect your home, your belongings, and your neighbors!
Unfortunately, stucco sandblasting almost always upsets someone in the neighborhood. Therefore it is our recommendation and our practice to see that the neighbors are advised before hand of the pending sandblasting activities. Typically, the neighbors are appreciative of the notice and the efforts that are taken to prevent damage to their properties while minimizing to the greatest extent possible the disruption.
The duration of stucco sandblasting depends heavily on the project. For example, a finished home with a pool and perfectly manicured landscaping will take longer to ‘protect’, than a construction site. Typically a small home will take at least a full workday to sandblast and clean up.
The most common textures typically seen today in our region are shown on the following pages and are supplied by Technical Services Information Bureau (TSIB). The images and more can be seen on the Technical Services Information Bureau webpage and can be viewed on line at www.tsib.org/plaster textures See the types here.
Absolutely! Changing an old dated texture to a smooth finish can have a miraculous impact on the look of your home. A smooth finish can give your home a beautiful, sophisticated look – there is almost nothing that can be done to profoundly improve the look of your home more than the installation of a smooth stucco finish.
The Pros: A perfectly smooth stucco finish is considered by many to be the premier stucco finish. This is because of the rich, expensive look and feel of the product. You will find smooth stucco finishes on the finest, most spectacular homes in the region; especially in the case for Mediterranean, Spanish style, or “Old World” homes. There is no finish that says “elegance” more than a smooth stucco finish.
The Cons: Smooth stucco finishes are expensive. The labor that is required is substantially more than other textures and thus will tend to cost more. Smooth stucco finishes consistently crack – it is normal and to be expected. Typically the cracks are hairline cracks, and considered to be “part of the look” of these classic finishes.
Back to Top
When installing a smooth finish it is critical that the usual care be taken to avoid cracking, but in addition to that, in order to minimize the tendency to crack, a Crack Reduction System (CRS) consisting of fiberglass mesh & acrylic-modified (synthetic) base coat over the brown coat can be done prior to the installation of the finish coat. This is the optimum strategy to reduce cracking. This process adds cost to the overall system, but will absolutely improve the resistance to cracking. The CRS system does not guarantee that there will be no cosmetic cracking, but should substantially reduce the propensity.
• Architectural stucco trim that include, window surrounds, sills, cornices, and more can be installed at surprisingly low cost. The improvement in the look and feel of the home can be stunning. • Veneer Stone – The accent of stone as a part of your architecture can be achieved quickly and easily utilizing beautiful new veneer stone products that can change the look of your home from bland to grand.
Yes. Knowing how to repair stucco is an art-form. Stucco repairs require a full understanding of how stucco reacts under certain conditions. Whether it’s a window patch, a stucco crack, or a serious stucco failure, we have the experience and know how to make the repairs professionally and as economically as possible. Additionally, we have many years of experience and knowledge of how to match existing textures and colors. Stucco repairs that have been incorrectly carried out can cause additional serious problems going forward. Stucco cracks that permit the passage of water almost always lead to stucco failure. Also if the repairs do not properly address the prevention of water intrusion into the repaired system, stucco failure is again inevitable.
Why Does Stucco Crack?
All stucco will crack, just like all concrete will crack. There are two fundamental types of stresses that cause stucco cracks—internal and external. Internal stresses are due to the natural curing and drying process of stucco, this usually is within 1 to 2 days. External stresses are due to the transfer of outside forces into the stucco assembly. Common examples are at the corners of windows and doors.
Can You Fix Stucco Cracks on my Smooth Finish?
If unacceptable cracking has taken place on a smooth finish, it can be repaired. However, “spot” repairs cannot be done easily. When repairs are done to smooth stucco, the optimum final step typically involves the recoating of the entire wall panel, corner to corner. This can be expensive in the case of large wall panels – the larger the panel, the more difficult the repair. The optimum method to repair cracks in smooth finish is to use the fiberglass mesh / acrylic base coat method of repair. This should prevent cracks from reappearing, and should minimize future cracking in the area.
Conventional stucco color pigments are subject to normal variations – and cannot be counted on to absolutely / positively be color perfect. Minor variations are normal and should be expected. We will always make sure that when we buy our color coat that the inventory comes from the same batch number if at all possible. In addition to its normal variations out of the bag, other factors can impact color variations including temperature, humidity, sun and wind. We will always use the benefit of our many years of experience to do what is necessary to minimize color variations. In conventional stucco, dark colors tend to be more problematic in achieving optimum color consistency. When the color is darkened past a critical threshold by volume, the color will have a tendency to exhibit significant blotchiness despite substantial care in the installation process. Therefore care should be exhibited when choosing dark colors in conventional stucco. Acrylic finish colors are far more stable than conventional stucco. Acrylic colors can be made up to match virtually any color – with very good stability and no blotchiness. Acrylic colors, like conventional colors, do become a bit more problematic when dark colors are chosen and must be applied with care by knowledgeable tradesmen.
Your existing stucco can be matched either utilizing standard colors, or lab matching done by our stucco provider. This is true with both conventional and synthetic (acrylic) finishes.
Our stucco manufacturers provide color charts with standard colors. Also, if you can provide a sample, we can have the lab make up custom matching samples for your approval.
Expo Stucco manufacturing is a premier supplier of state of the art conventional stucco products and our choice when the specification is in our hands. The Expo standard colors can be seen on the web at: http://www.expostucco.com/expo-color/category/classic-colors/ Of course we can provide you with a color chart brochure and provide actual samples for your review upon request.
Senergy Stucco Wall Systems is our preferred supplier of synthetic / acrylic based stucco finish systems. Senergy colors are extremely color stable and can be provided to match virtually any paint color. you can see the Senergy color chart on the web (Click here): Senergy Color Chart Again, of course we can provide you with a color chart brochure and provide actual samples for your review upon request.
Products that increase the adhesion of plaster to substrate or plaster to plaster are called bonding agents, and are either surface applied to a substrate or integrally mixed into the plaster. If contamination is present on the substrate surface, good bond is inhibited. This is generally not a concern with new masonry walls, but can be an issue with new cast-in-place concrete as it may have residual form release agent on its surface. Older concrete or masonry walls may have bond-inhibiting characteristics, in the form of paint, sealer, some other coating, or dirt on the surface. As such, bonding agents are more likely to be considered for repair and renovation work over either concrete or concrete masonry. It is optimal practice to prepare the solid substrate so a bonding agent is not necessary. The prepared surface should be clean (all surface materials removed), sound (hard surface), and mechanically roughened. Methods for achieving these criteria include sand blasting and high-pressure water blasting. When this type of preparation does not result in a clean, properly roughened substrate, bonding agents are valuable. Different bonding agents have different chemical formulations, and thus different performance characteristics. Bonding agents do not guarantee performance. Research is necessary to identify the bonding agent best suited to particular conditions. But where prepared surfaces seem questionable, and lathing is not an option, a bonding agent may be necessary. Rather than using bonding agents, another option for low-absorption surfaces is to apply a dash-bond coat. This cement-rich slurry is dashed against the base surface by hand with a brush, trowel or paddle, or by machine. Most of the surface is covered with the plaster. The high cement content provides a tenacious bond. This material is left unfinished so that a rough base is created for the scratch coat.
This is a common question that often arises when people are rehabbing or updating older construction. Plaster is a cost-effective finish, relatively easily installed, that improves the appearance and creates a water-resistant wall surface. A painted surface will not typically absorb water and, as such, is a substrate to which stucco will not readily bond—at least not uniformly. There are two basic alternatives to covering a painted brick surface with a new coating of portland cement plaster.
1. Sand blast or water blast to remove the paint in its entirety. Then direct-apply a two coat system. It is essential to have a surface that is uniformly absorptive to accept the plaster coating. In addition, it may be beneficial to use a bonding agent or dash-bond coat with this approach.
2. Attach paper-backed lath or install appropriate building paper between wall and attached metal lath to provide a moisture barrier and to serve as a bond breaker. Apply traditional three-coat stucco to metal lath and accessories. In this approach, the idea is to treat the plaster like a sheathed system, using metal lath to support the plaster on the substrate, while completely isolating the plaster layer from the backup with building paper. This prevents a partial bonding situation, which could set up undesirable stresses in the plaster and lead to cracking.
3. Wrap the building in polystyrene foam that is then laminated with fiberglass mesh embedded into acrylic-modified base coat. This is an EIFS (Exterior Insulation Finishing System). The Foam is bonded to the substrate and has the additional benefit of providing a substantial insulating factor to the structure. Acrylic or conventional finish coat can be applied to the system. A $1500 Tax Credit May be available for this process.
Yes. Polystyrene foam sheeting can be installed before stucco to create an exterior insulating barrier sometimes described as EIFS (Exterior Insulation Finishing System). The home can then be wrapped in fiberglass mesh embedded in Acrylic Modified Basecoat and finished with color coat of either acrylic or conventional finish coat. A $1500 Tax Credit may be available for this process.
This question comes up in both new and repair construction. Designers need to know how much weight the stucco adds to the wall so that they can be sure the structural system provides adequate support. In new construction, the structural system usually has more than enough strength to support installed plaster. In buildings that are being updated or retrofitted, however, stucco may be placed over existing construction. Especially in this case, designers should verify that the added weight of the new stucco will not exceed the structure’s ability to support it along with whatever other materials remain in place. Concrete or masonry walls generally have sufficient structural strength to support the additional weight. In wood frame construction, support members (studs) should be checked to ensure they can carry the extra load. On wood framing, three-coat plaster is typically installed over metal lath to a 7/8 in. nominal thickness. A typical plaster mixture weighs about 142 pounds per cubic foot, roughly the same as mortar, and this amount of material would cover about 13.7 sq ft at 7/8 in. thick. The metal lath may add a small additional amount of weight, so the end result is that three-coat stucco weighs about 10.4 lbs per sq ft (psf) installed.
Portland cement plaster is suited to virtually every type of climate, whether wet or dry and hot or cold. It is popular in coastal environments because it is unaffected by moisture, but when metal lath is part of the system, there are potential concerns due to the elevated chloride levels in the environment. In coastal areas, air is literally salty: it carries chlorides. This is an aggressive ion that corrodes metal. Hardened plaster is not affected by chlorides. If the plaster is direct-applied to concrete or masonry backup, there is little or no metal reinforcement in the plaster. If a 3-coat system is installed, whether the backup is frame construction or to achieve mechanical bond over a solid substrate, metal lath is attached to structural supports to hold the plaster to the wall. Metal lath is required to be galvanized, and embedding it in a highly alkaline environment like portland cement plaster provides added protection from corrosion. Historically, the combination of galvanized coating and plaster cover protects the metal. This makes it critical to minimize cracking of the plaster, which would otherwise provide a direct path for chlorides to reach the steel. Methods to minimize cracking include proper consolidation during installation, appropriate contraction joint spacing and proper curing of the freshly placed stucco material. There are other protective measures that can be taken in these extreme exposures. These include stainless steel lath, which is more resistant to corrosion due to chlorides, and new fiberglass and synthetic based lath that is significantly more resistant to corrosion than metal. Apptek is now recommending for all properties in the vicinity of the ocean Permalath – Fiberglass Lath, and Vinyl Corner Bead, screed and stucco accessories. This is a system that will yield a long robust life, without the concern or corrosion of metallic members and the resultant deterioration of the stucco.
Black Paper vs. Tyvek
Often we have been asked to elaborate on the difference between standard black building paper and Tyvek housewrap. Based on our experience at Apptek, we have made some observations that may be helpful. One rather powerful observation is that when we have done repairs or re-stucco on projects of 30 years or older, we have somewhat consistently found that many times the old building paper (classic black paper) is badly degraded and basically non-performing. We are comfortable that the new synthetic building wraps will weather the decades better. We have also observed that if there is ever a delay in the construction process and the building paper is exposed to the elements for a period of greater than a handful of weeks the black paper becomes degraded. We have observed that if the building wrap is synthetic like Tyvek, it can survive for a much longer period of time, even a few months, without substantial degradation. At Apptek we are certified installers of Tyvek. Apptek also recommends using Tyvek building wrap as an upgrade to further ensure a longer life for the system in hostile environments that include seaside environments. Click on icon below to see Tyvek’s description of its benefits.
The corrosion of metal lath over time in homes near the influence of the ocean, influences the life of the stucco. PermaLath is a patented, non-metallic lath reinforcement that is believed by many experts to be a superior alternative to metal lath and stucco netting. It offers numerous benefits such as easier handling, enhanced safety during installation, reduced installation labor and elimination of corrosion. PermaLath is available in two version. The original PermaLath was designed specifically for use in the 3/8″ to 1/2″ thick stucco systems, and PermaLath 1000 was developed for use in traditional three coat 1/2″ to 7/8″ thick stucco systems and behind stone veneer.
Acrylic finishes are synthetic stucco color coat finishes that are used as an alternative to conventional color coat. At Apptek our typical use of acrylics is over conventional lath, scratch and brown coat. The benefits of acrylics are related to its elastomeric qualities, allowing the material to flex and thus bridge typical stucco surface cracking. Additionally acrylics are resistant to moisture absorption, thus providing additional protection of the subsurface from corrosion and deterioration. Another quality of acrylics that is deemed to be beneficial is its color stability and consistency, and the fact that it can be made to match virtually any paint color.
The length of time it takes to complete stucco work is entirely dependent on the scope of the work. Cleaning and rejuvenating stucco can take less than a week, but a comprehensive restucco job including relathing, sandblasting, work by other contractors can take several weeks. Apptek, however, has established itself as a very efficient contractor, and very proficient in meeting schedules. At the time we provide an estimate, we can also provide an estimated time line as well.
After lath is complete, the “scratch coat” of stucco is installed. The scratch coat is normally 3/8 inch thick and typically no more than a day or two is required for cure time. Following the curing of the scratch coat, the “brown coat” is installed. The brown coat is also approx 3/8″ thick and should cure a minimum of one week prior to installation of the final “color coat”. We recommend that the brown coat be allowed to cure as long as possible because as the cement fully hydrates, the propensity for cracking diminishes. Also, it is our standard practice to “wet cure” the brown coat for 48 hours following installation. This is done to further promote the full hydration of the cement matrix and thus further reduce the propensity for cracking.
Our standard warranty for stucco is two years. We will be happy to provide you with the verbiage of our standard warranty upon request. however, the practical reality is that if you ever have problems with our work even after the warranty period, we will do everything within reason to help you resolve your problem.
The principals of the company have been doing business as Apptek Stucco for approximately 20 years.
Yes. Certificates of Liability Insurance and Workman’s Comp Insurance coverage will be made available to all customers prior to the commencement of work. Copies of the certifications are published on our website in the “about us” section.