A & M Lath & Plastering Inc | Stucco - Hayward California

- Frequent Questions & Answers -


If you own a stucco home you are aware of the low-maintenance, sound-insulating benefits of this beautiful exterior material. Here are some frequently asked questions that can cover the basics. We are here to answer any of your questions – none are too simple or complicated – so call us and have a conversation. Better yet, call and make an appointment and let us see your home or commercial project so we can answer your specific questions intelligently.

Q: What's in Stucco?

  • True stucco is made from a mix of Portland cement and sand, with various amount of time, pigment and other bonders.

Q: How long does stucco last?

  • Properly applied stucco lasts from 50 to 100 years with proper maintenance.

Q: Can the stucco color be changed?

  • Yes, color can be added at the time of refinishing your home.

Q: Can the texture of my stucco be changed?

  • Yes, sufficient coats of stucco can be applied and textured over an existing finish.

Q: What is the advantages of stucco?

  • It can withstand changes and weather conditions, resisting the harsh effects of rain, snow, fire resistant, hail and gusting winds.
  • Stucco never needs to be painted. It is maintenance free, worry free, for years to come.
  • Stucco adds an excellent R-Value, and adds thousand of dollars to the market.
  • Stucco never goes out of style.
  • Barrier to termites, insects, and vermin.

Q: Why does stucco crack?

  • Stucco is susceptible to cracking by nature. Is shrinks a little as it dries and doesn't take much movement to make a tiny crack at the surface. Over the time stress movements can occur. These stresses appear as cracks in the coat. Most cracks are aesthetic in nature and do not damage the integrity of the building structure.

Q: How thick is the stucco treatment?

  • This will vary depending on texture but the final two coats of stucco total approximately 1/8 to 3/16 –inches.

Q: What is white-wash?

  • Getting your home "white-washed" is similar to getting your home painted. Typically when stucco is applied to an existing home there is a two-part process, a wash coat, and a texture coat. The problems that arise with only white-washing your home are the shortened life of the job, and the cost of future stucco repair and finishing. The reason stucco lasts so long is that the cement is also mixed with sand.

Q: Plaster is placed in two or three layers, or "coats." Are there guidelines or restrictions on placing each successive coat?

  • Time Delay Between Each Coat of Exterior Cement Plaster Based on IBCRequirements:
  • Coat Moist curing (minimum period) Minimum interval between coats
    1. First 48 hours* 48 hours
    1. Second 48 hours 7 days
    1. Finish ---------- ---------
  • *An exception to these time limits occurs with a method called double-up or double-back. See below.

Q: How is stucco applied?

  • Stucco is applied in several layers to a wire-lath base over a wood frame construction or a masonry surface. Building paper must be used under the wire-lath bade to prevent moisture damage. A proper stucco application requires three coats: a 1/2-inch- thick "scratch" coat, a 1/4-inch-thick "brown" coat and an 1/8-inch thick "finish" coat or "dash" coat.

Q: How durable is stucco?

  • Although stucco is durable, it can develop cracks or crumble as time passes. Lasting repairs must be made with care. Pre-mixed stucco repair compound can be applied to small, deteriorating areas. Repairing larger areas requires chipping away damaged stucco, cutting and attaching a metal lathe and mixing your own stucco.

Q: What about stucco siding?

  • Stucco siding became a popular alternative to true stucco due to its ease of installation. Yet if installed without built-in drainage, it will be damaged by moisture. Between 1995 and 1996, building inspectors discovered moisture damage to nearly every home in New Hanover County, North Carolina, that had synthetic stucco siding. Manufacturers have since introduced stucco siding systems that include a drainage plane.

Q: Why hire a licensed, insured plaster?

  • Most Licensed contractors are competent, honest, hardworking and financially responsible. However, most of the problem the CSLB sees could be prevented if homeowners knew their home improvement right and took responsibility for their project. A responsible and informed consumer can work more effectively with reputable contractors, and can avoid being victimized by unscrupulous or unlicensed companies.

Q: What are the signs to look for to determine if my home has a problem?

  • On the interior, if the bottoms of windows are discolored or the base trim is warped or carpet is wet, these are indications of a leak. If there is a moldy smell in the house, there may be leaks into the wall cavities that may not show other signs of leakage. On the exterior, if there are brown streaks below the corners of windows or where window units are joined, it is likely there is a leak at that location. Intersections of walls and roofs are also susceptible to leaks, which will be indicated by brown streaks.

Q: What causes the problems?

  • The paper around windows and other openings was installed incorrectly.
  • Head flashing was not used on windows (windows with flanges were thought to be self-flashed).
  • One layer of paper was used. Water may be leaking through the paper.
  • The windows themselves leak.
  • Kickout flashing was not installed at the wall/roof intersections where the roof line does not extend below the wall.
  • The deck ledger board was not flashed.
  • Moisture from rain during construction or wet building materials remain in the wall (construction moisture).
  • Interior moisture is permeating into the wall.
  • Lack of drying capacity. All walls will likely leak sometime during their life.
  • In addition condensation and construction moisture will be in the walls. Stucco walls are very tight and cannot withstand much moisture without creating mold and rot.
  • Solar drive may be pushing moisture from a wet stucco wall into the wall cavity.
  • Type 15 felt may be acting as a vapor retarder trapping moisture in the wall.
  • Oriented strand board (OSB) sheathing has a low perm rating and it may be acting as a vapor retarder creating a double vapor retarder situation. In addition OSB absorbs and retains moisture making it vulnerable to mold and rot.
  • The staples that stick through the sheathing are collecting frost or condensation and dripping within the wall cavity.
  • The high number of staples used to fasten the lath creates many penetrations that could both leak and condense moisture.
  • The staples were driven into the lath with excessive force causing the lath to cut the paper creating a leak.
  • Wind driven water is getting on the wall through the soffit vents and running down the wall between the sheathing and the paper.
  • Weep screeds were not used at the bottom of the stucco. This may prevent trapped water from draining.
  • Stucco was installed below ground. This may prevent trapped water from draining or may wick water up to the framing. In addition, when stucco is applied below grade there is no clear definition of where grade should be and often the grade is placed against the wood framing causing a guaranteed rot situation.
  • Stucco is installed directly on the foundation without paper or a weep screed. This prevents trapped water from draining.
  • Landscape trees or bushes that contact the stucco create an area that introduces and holds moisture in the stucco. The moisture permeates into the wall.

Q: I own a stucco home, and I don't see any symptoms of leaks right now. Is there any preventative action I can take that will keep problems from occurring?

  • Most of the problems we have seen are caused from leaks around windows. Caulking the sides and bottom of the window will help prevent water infiltration. There are different schools of thought on caulking the top of the windows. One is to caulk the top of the window to prevent water from getting in and the other is to not caulk the top so water that is behind the stucco but on the tarpaper can get out. A moderate position is to caulk the top of the window but leave some small openings in the caulk to let any water that may be on the tarpaper out. Additional openings and penetrations such as doors and vents should also be caulked.

Q: If there is a problem with the stucco on my home, what will be required to correct it?

  • A building permit is required for stucco repairs. The building code requires that all wood with mold or rot be removed and repaired. Areas that do not show signs of leaks, mold, rot or deterioration may remain.

Q: When is total replacement necessary?

  • Complete replacement of the stucco with new stucco of either a traditional or modern mix will probably be necessary only in cases of extreme deterioration-- that is, a loss of bond on over 40 to 50 percent of the stucco surface. Another reason for total removal might be stucco has been so compromised by prior incompatible and ill-conceived repairs that patching would not be successful. When stucco no longer exists on a building there is more flexibility in choosing a suitable mix for the replacement. Since compatibility of old and new stucco will not be an issue, the most important factors to consider are durability, color, texture and finish. Depending on the construction and substrate of the building, in some instances it may be acceptable to use a relatively strong cement-based stucco mortar. This is certainly true for many late-nineteenth and early-twentieth century buildings, and may even be appropriate to use on some stone substrates even if the original mortar would have been weaker, as long as the historic visual qualities noted above have been replicated. Generally, the best principle to follow for a masonry building is that the stucco mix, whether for repair or replacement of historic stucco, should be somewhat weaker than the masonry to which it is to be applied in order not to damage the substrate.

Q: How do I understand different types of stucco products?

  • There are many contemporary stucco products on the market today. Many of them are not compatible, either physically or visually, with historic stucco buildings. Such products should be considered for use only after consulting with a historic masonry specialist. However, some of these prepackaged tinted stucco coatings may be suitable for use on stucco buildings dating from the late-nineteenth or early-twentieth century, as long as the color and texture are appropriate for the period and style of the building. While some masonry contractors may, as a matter of course, suggest that a water-repellent coating be applied after repairing old stucco, in most cases this should not be necessary, since colorwashes and paints serve the same purpose, and stucco itself is a protective coating.

Q: Can you use Exterior Stucco in an interior application?

  • Yes, stucco color coat may be successfully applied to a portland cement base substrate in an interior application. However exterior stucco color coat will not stick to drywall or other non-cementicious surfaces unless an adhesive is applied to the surface prior to stucco application.
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