Painting Exterior Stucco

CSI Division
Division 9 - Finishes
Section
Exterior Painting
Last Modified

Technical Procedures Disclaimer

Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.

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We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.

PART 1–GENERAL

1.01 SUMMARY

  1. This specification provides guidance on painting exterior stucco surfaces.

  2. Unlike wood and metal, painting a stucco surface does not afford any extra protection.

  3. Early stucco was generally left unpainted. The natural colors of the sands and aggregates used in the stucco mixture provided the color. However, repairs may require the stucco to be painted when a perfect color match between the original material and the patches cannot otherwise be achieved.

  4. Read “General Project Guidelines” along with this specification. These guidelines should be reviewed prior to performing this procedure and should be followed, when applicable, along with recommendations from the Regional Historic Preservation Officer (RHPO). The guidelines cover the following sections:

    1. Safety Precautions

    2. Historic Structures Precautions

    3. Submittals

    4. Quality Assurance

    5. Delivery, Storage and Handling

    6. Project/Site Conditions

    7. Sequencing and Scheduling

    8. General Protection (Surface and Surrounding)

1.02 SYSTEM DESCRIPTION

  1. Paint manufacturers have developed paint systems which are made to work together. These systems include primers and appropriate, compatible top coats, which can vary depending on the substrate and manufacturer. Therefore, only use compatible primers and top coats that are made by the same manufacturer.

  2. A paint film is in good condition when it is clean and free of any peeling or cracking. It is not chalking, and it retains its color and gloss.

1.03 DELIVERY, STORAGE AND HANDLING

  1. Paints shall be in sealed containers that legibly show the following information:

    1. Designated name.

    2. Formula or specification number.

    3. Batch number.

    4. Color.

    5. Quantity.

    6. Date of manufacture.

    7. Manufacturer’s formulation number.

    8. Manufacturer’s directions including any warnings and special precautions.

    9. Name of manufacturer.

  2. Pigmented paints shall be furnished in containers not larger than five gallons.

  3. Paints shall be stored on the project site and shall be stored to prevent freezing.

  4. All paints shall be kept covered and safeguards taken to prevent fire.

1.04 PROJECT/SITE CONDITIONS

  1. Unless otherwise recommended by the paint manufacturer, the ambient temperature shall be at least 50 degrees Fahrenheit. Consult manufacturer for upper temperature limits.

  2. Do not apply latex based paints when the temperature is expected to fall below 50 degrees Fahrenheit during the first 24 hours after application.

  3. Do not apply paint when the relative humidity exceeds 85%. Drying times are also affected by relative humidity. Those stated by manufacturers generally are based on 50% relative humidity and approximately 77 degrees Fahrenheit.

  4. Only apply paint to surfaces that are in the shade. Therefore,

    1. The west elevation should be painted in the morning when the sun is shining on the east elevation,

    2. The north elevation should be painted around noon when the sun is shining on the south elevation,

    3. The east elevation should be painted in the afternoon when the sun is shining on the west elevation, and

    4. The south elevation should be painted late in the afternoon when it is in full shade.

  5. Do not apply paint to damp surfaces, in misty or rainy weather, in the snow or where there is visible ice or frost on the surfaces.

PART 2–PRODUCTS

2.01 MATERIALS

NOTE: Chemical products are sometimes sold under a common name. This usually means that the substance is not as pure as the same chemical sold under its chemical name. The grade of purity of common name substances, however, is usually adequate for stain removal work, and these products should be purchased when available, as they tend to be less expensive. Common names are indicated below by an asterisk (*).

  1. Acrylic Latex Paint.

    1. All paint used shall be from the same manufacturer and shall be appropriate for the conditions encountered on the job site.

    2. Acrylic latex paints are recommended over vinyl acetate latex paints because the acrylics are more alkali resistant, important when painting stucco (or brick). They are more flexible and “breathe” more than the oils do. Many are also self-priming so the same paint can be used for both the prime coat and top coat. Latex paint can also be applied to slightly damp surfaces, though they must be absolutely clean and free of any chalking paint.

    3. Oil/alkyd based paints may also be used according to the method described in PART 3–EXECUTION, below.

  1. Masonry conditioner/sealer if recommended by paint manufacturer and RHPO.

CAUTION: SEALER MAY TRAP MOISTURE WITHIN THE STUCCO, CAUSING SPALLING OR PAINT/SEALER FAILURE.

    1. The sealer will prevent old stucco from absorbing the water from the latex top coat which would prevent the paint from adhering properly.

    2. Conditioners/sealers are also alkali-resistant and will prevent adverse chemical reactions from occurring between the stucco and oils in oil/alkyd based paints.

  1. Mineral Spirits (as recommended by paint manufacturer to thin conditioner):

    1. A petroleum distillate that is used especially as a paint or varnish thinner.

    2. Other chemical or common names include Benzine* (not Benzene); Naphtha*; Petroleum spirits*; Solvent naphtha*.

    3. Potential Hazards: TOXIC AND FLAMMABLE.

    4. Safety Precautions:

      1. AVOID REPEATED OR PROLONGED SKIN CONTACT.

      2. ALWAYS wear rubber gloves when handling mineral spirits.

      3. If any chemical is splashed onto the skin, wash immediately with soap and water.

    5. Available from construction specialties distributor, hardware store, paint store, or printer’s supply distributor.

2.03 EQUIPMENT

  1. Brushes.

    1. Use nylon bristle brushes for water-based paints.

    2. Use natural bristle brushes (pre-conditioned by soaking in linseed oil for 24 hours) for oil-based paints.

    3. NOTE: DO NOT USE THE SAME BRUSH FOR BOTH TYPES OF PAINT.

  2. Garden hose or low pressure water spray equipment.

  3. Paint rollers.

  4. Paint spray.

PART 3–EXECUTION

3.01 SURFACE PREPARATION

  1. Make sure all stucco repairs have been made and the surfaces to be painted are sound and dry.

  2. Using scrapers and stiff bristle brushes, remove any loose, flaking paint.

  3. To remove any old chalking paint:

    1. Wash surfaces with a non-ionic detergent using low pressure water (80-100 psi) or a garden hose.

      1. If mildew is a problem, add bleach to the detergent.

      2. For guidance on cleaning exterior masonry and stucco, see “Removing Biological Growth from Exterior Masonry and Stucco”.

    2. NOTE: DO NOT USE DETERGENT CONTAINING AMMONIA.

    3. Thoroughly rinse the surface with clean, clear water and allow to dry.

  4. If recommended by the paint manufacturer, apply a masonry conditioner/sealer which has been thinned if necessary according to manufacturer’s instructions:

    1. Apply using brush, roller, or spray, only as much as surface will absorb.

    2. NOTE: DO NOT ALLOW A VISIBLE GLAZE TO APPEAR ON THE SURFACE OF THE STUCCO. DO NOT APPLY TO A DAMP SURFACE BECAUSE THE GLAZE WILL NOT SUFFICIENTLY PENETRATE A DAMP SURFACE.

    3. Allow to dry as per manufacturer’s instructions.

  5. Scrape or brush off all loose paint. Spot prime before reapplying paint.

3.02 ERECTION, INSTALLATION, APPLICATION

  1. Follow manufacturer’s instructions when selecting and applying paint.

    1. Use a brush or roller to apply two coats of paint to ensure complete coverage. Spray equipment may also be used.
    2. NOTE: SOME PAINT MANUFACTURERS DO NOT RECOMMEND ROLLER APPLICATION. CONSULT MANUFACTURER’S DIRECTIONS FOR PROPER APPLICATION METHODS.
    3. Allow adequate drying times between each coat of paint.

NOTE: FOR OPTIMAL RESULTS WHEN USING ACRYLIC LATEX PAINTS, MAINTAIN A TEMPERATURE OF 50 DEGREES FAHRENHEIT FOR AT LEAST THE FIRST 24 HOURS AFTER APPLICATION.

  1. If using oil/alkyd paint, any new patches must be allowed to cure for at least a year before painting, unless a masonry conditioner/sealer has been used. Apply two top coats, using a brush for complete coverage.

 

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Last updated: Mar 4, 2024
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