Two Different Ways to Color a Wall

Integral-color stucco (the color coat). Most stucco in Albuquerque gets its color from the finish coat itself. The Portland Cement Association explains that stucco color comes from the cement and aggregate, often adjusted with mineral oxide pigments. Factory-blended finishes come with the color pre-mixed in the bag. A fog coat is a thinner cement-based color refresh for unpainted stucco; Sika's fog coat bulletin describes it as porous like stucco and notes it won't peel like conventional paint.

Paint and elastomeric coatings. Paint is a film applied over the stucco. Elastomeric coatings are thick, flexible acrylic films designed to stretch over hairline cracks. Sto's StoColor Lastic data sheet, for example, describes a coating that bridges hairline cracks but says not to use it on cracks wider than 1/32 inch.

Both are legitimate finishes. They behave differently, and it's hard to switch from one to the other.

The Moisture Question

Stucco walls get wet and need to dry. Water gets in through cracks, flashing gaps and wind-driven rain, and moisture moves through the wall as vapor.

The Northwest Wall & Ceiling Bureau, a stucco trade association, puts it directly:

  • Elastomeric coatings are often low in vapor permeability and can trap moisture trying to leave the wall.
  • An elastomeric "should 'not' be used to solve a water intrusion and/or a flashing problem."
  • They have worked well on stucco systems with good flashing and drainage.
  • Paints and coatings for stucco should have a perm rating of 7 or higher.

Newer elastomeric products publish higher permeance than older ones, so this varies by product. The practical rule: read the data sheet for perm rating, and never use paint to cover a leak.

On an adobe home, this matters even more. New Mexico's earthen building code allows coatings on adobe only if they don't form a vapor barrier. See cement stucco on adobe.

Stucco Cracks or Stains?We look at the cause first, then tell you whether it needs a patch, a repair or a re-coat.
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Painting Is Hard to Undo

Once stucco is painted, a new color coat can't simply go on top. The manufacturer's data sheet for one widely used factory-blended stucco finish, LaHabra Premium Stucco Finish, requires a surface that is "sound, clean, dry, unpainted." Sika's fog coat is likewise specified for unpainted stucco.

Contractors handle previously painted walls in different ways, from stripping the paint to bonding agents over sound paint, but the color-coat manufacturer's requirements govern. The NWCB also notes that elastomeric coatings can be difficult to remove or recolor later.

If you like the option of going back to a traditional stucco finish someday, that's a reason to think twice before painting.

New Mexico Sun and Heat

  • Application temperature. Stucco finish manufacturers warn that applying in direct sun in hot weather can affect appearance. LaHabra lists a maximum surface and air temperature of 120°F. Summer work on west and south walls needs planning.
  • Fading. Manufacturers market integral-color stucco as fade-resistant, and acrylic finishes publish UV test results. Paint fades on its own schedule depending on the product and color. No source we found gives a reliable repaint interval for Albuquerque, so ask for the product's warranty.
  • Dark colors. Walls & Ceilings notes cement-based stucco can hold only so much pigment, so very dark tones aren't recommended in a cement finish. Our stucco color trends guide covers color choices that work here.

Painting New Stucco

New stucco is strongly alkaline and has to cure before it's painted. Sika's painting bulletin calls for waiting until the stucco is fully cured, normally 28 days, and testing that pH has dropped to 9.5 or less, or using an alkali-resistant primer. Other manufacturers publish shorter waits. Follow the paint manufacturer's instructions for the specific product.

How to Decide

A new color coat usually makes sense when:

  • The stucco has never been painted.
  • You want the look and breathability of a cement finish.
  • Cracks are being repaired anyway and the wall needs a uniform finish over the patches.

Paint or an elastomeric may make sense when:

  • The stucco is already painted.
  • You want a color that a cement finish can't hold.
  • The wall is sound, the flashing is right, and you want to bridge hairline cracks.

Either way:

  1. Fix leaks and flashing first. See where a roof meets a stucco wall.
  2. Repair cracks properly before coating. See what causes stucco cracks.
  3. Check the wall type, especially on adobe.
  4. Ask for the product data sheet and warranty.

Timberwolf does stucco repair and re-coats. See our stucco page.