Stucco as a Viable Option for Metal Structures
- Heather Hale
- Oct 27
- 3 min read
Metal buildings are often lauded for their durability and cost-effectiveness, but let's face it – they aren't always the most aesthetically pleasing. As builders and framers, you're constantly seeking ways to enhance both the functionality and visual appeal of your projects. Enter stucco: a versatile finish that can transform the utilitarian look of metal structures into something truly remarkable. Here we'll look into why stucco is emerging as a strong contender for metal buildings, exploring its advantages, challenges, and the best practices for successful application – like using the ET&F® (a BECK brand) STUCCOFAST® System.
Why Stucco on Metal? Advantages and Considerations
The integration of stucco with other materials, and on its own, is a growing trend. A sizable portion of this growth stems from metal building applications. Why? Because stucco offers a winning combination of aesthetic appeal and practical benefits.
Stucco's versatility allows for a wide range of textures and colors, enabling you to create custom looks that complement any architectural style. It's also incredibly durable, offering excellent fire resistance and weather protection. However, applying stucco to metal isn't without its challenges. Metal's thermal expansion and contraction, potential for condensation, and smooth surface require careful consideration and specialized techniques.
Surface Preparation: The Foundation for Success
Successful stucco application on metal hinges on meticulous surface preparation. Start with a thorough inspection to identify and remove any contaminants like dirt, grease, mill scale, or protective coatings. Pressure washing and stiff brushes are your allies here. Remember, the smooth nature of metal means you'll need to create mechanical attachment points. This is where metal lath comes in.
Lath Attachment: Bridging the Gap Between Metal and Stucco
Metal lath acts as the crucial bridge between the metal substrate and the stucco. Ensure your lath conforms to ASTM C847 specifications and is fastened directly to structural members, not just the sheathing. Fasten at maximum intervals of 7 inches on center and ensure the lath accessories' flanges directly contact the lath. Overlap the lower edge of each lath sheet over the upper edge of the sheet below for optimal performance.
Moisture management is paramount. Implement a comprehensive drainage plane system, including a weather-resistant barrier and drainage mats designed specifically for stucco. Consider using self-adhered vapor permeable membranes for both weather and air barrier functions.
Mastering the Three-Coat System
The traditional three-coat system remains the gold standard for stucco applications. This involves a scratch coat, a brown coat, and a finish coat, resulting in a total thickness of approximately 7/8 inch. Each coat requires specific curing periods: typically, 72 hours for the scratch and brown coats, and 48 hours for the finish coat. During curing, protect the surfaces from direct sunlight and maintain adequate moisture levels through fog curing.
Addressing Challenges
Applying stucco to metal structures presents unique hurdles. Metal's thermal expansion can cause cracking, and its tendency to condense moisture can lead to corrosion. Weight is another factor; a three-coat system can weigh 10-12 pounds per square foot.
Solutions include strategically placed expansion joints, polymer-modified stucco for flexibility, and comprehensive drainage systems. For weight concerns, consider one-coat or Exterior Insulation and Finish Systems (EIFS), which typically weigh 4-6 pounds per square foot.
ET&F® Model 500MA STUCCOFAST® System
To streamline the lath attachment process, consider the ET&F® Model 500MA
STUCCOFAST® system. This pneumatic coil nailer features a magnetic washer holder for easy placement of steel or plastic washers, securing the wire lath during installation. It uses our plastic rope collated AKN-100 series framing pins, specifically designed for cold-formed steel. This system improves efficiency and reduces labor demands.
Embrace the Potential
Stucco offers a compelling solution for enhancing the aesthetic and functional performance of metal structures. By understanding the challenges and implementing best practices, you can unlock the full potential of this versatile finish. Don't let the utilitarian look of metal limit your designs. Embrace stucco and transform your metal buildings into stunning, durable, and code-compliant masterpieces using the Model 500MA STUCCOFAST® system
