What is Stucco? Material, Coats, Painting and More

How Many Coats of Stucco Are Needed?

Stucco wall background.
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Stucco is cement plaster applied over wall and surfaces inside and outside buildings. The stucco is a plaster type material that is made from cement, sand, and lime. Stucco provides a hard, reliable, durable and low-cost surface that requires little maintenance and can be used to obtain different textures and finishes. Stucco might be applied over metal lathe; a galvanized wire mesh used that must be covered that needs to be covered protecting it against rust. The purpose of the metal lath allows the stucco to adhere to become stronger.

How Many Coats of Stucco Are Needed

The stucco must be applied over lath to keep it away from the frame sheathing by about one-quarter of an inch. Stucco must be applied using thin coats; the first one must be forced into the lath, so the mesh is entirely embedded within the stucco mix. ​It is recommended to apply stucco in three different coats, adding over one inch of stucco surface once the plaster has been applied.

A 3-coat stucco system consists of a scratch coat, brown coat, and finish coat. The scratch coat is applied first to provide a strong base for the system. It's embedded in metal lath, which strengthens and secures the coat. The brown coat is applied next to create an even surface for the finish coat. The finish coat is applied last, creating the decorative finish on the wall surface.

Building Codes Standards on Stucco

One of the major secrets to applying stucco is mixing stucco, so every batch has the same perfect consistency The International Building Code (IBC) provides rules for the minimum time delay between each coat of plaster. The two standards from the ASTM that regulate the application of stucco are:

  • ASTM C 926 Standard specification for application of Portland Cement-based plaster
  • ASTM C 1063 Standard specification for installation of lathing and furring to receive interior and exterior Portland Cement-based plaster.

Pre-Mixed or On-Site Mixed Stucco

Commercially prepared stucco mixes can be an easy solution on your construction project. One of the major secrets to applying stucco is mixing stucco, so every batch has the same perfect consistency. However, stucco can also be mixed by you using:

  • Three parts sand
  • One part Portland cement
  • Hydrated lime to ten percent of the cement by the volume.

Mixing stucco is commonly on a one cubic foot basis, mixing Portland cement, blended hydraulic cement, masonry cement, plastic cement, hydrated lime and fly ash, three cubic feet of plaster sand (coarser than masonry sand), and from four to seven gallons of water. The formula used to create the stucco will determine if admixtures are needed.

The slower the stucco dries, the stronger it will become. In sunny and hot locations stucco must be shaded to prevent the dehydration of the stucco mix. If using commercially prepared stucco, you must follow manufacturer’s instructions. Do not apply stucco if the weather temperature is less than forty degrees.

Stucco Mix Manufacturers

The list below contains some of the stucco manufacturers that you can reach out to if you plan on using these mixes:

  • Shamrock Stucco
  • Parex USA, Inc.
  • Omega products
  • Mission stucco
  • Merlex stucco, Inc.
  • E-z haul ready mix, Inc.
  • Expo stucco products
  • Eagle building materials
  • California stucco products corp.
  • Bmi products, Inc.
  • Atlas eps

Can Stucco be Stained?

Stucco can be finished with natural color or can be mixed to produce any preferred color. Some contractors tend to use warm colors such as yellow, pink, or orange. Beige is one of the most favorite colors used in stucco. However, when speaking of colors, white has always been preferred over other colors. Of course, white is always good for any home. Leave ​the mortar to dry out for at least six weeks before applying cement paint or color wash if required.​