In the past decade, 3-D printed concrete technology has made significant strides moving from theoretical concept to practical process for building of homes, schools, hospitals, hotels, restaurants and other structures. The emergence of 3-D printed concrete means faster, more affordable and more efficient automated construction than ever before. A critical next step in the evolution of 3-D printed concrete structures is determining the best method for giving raw ridged walls an attractive, durable exterior finish. Less time, labor and cost intensive than using masonry or siding, factory pre-blended stucco is potentially the best choice for finishing 3-D printed concrete exterior walls. 

A natural extension to the automated 3-D process that requires stucco and plastering professionals little to no surface preparation, pre-blended stucco is easily applied to concrete with a bond strength to give walls a long-lasting smooth or slightly textured, flat surface. 

A proven high-quality exterior finish over block, wood and other substrates for more than 50 years, pre-blended stucco is the seamless option for 3-D printed concrete structures. Many of the same reasons stucco and plastering professionals use pre-blended stucco in other types of construction have also proven true for finishing the exterior of 3-D printed concrete structures. However, the unmatched speed to finish an exterior wall and the unique ability to bond directly to 3-D printed concrete are what really makes it the ideal building material for these jobs. 

Why Pre-Blended Stucco for 3-D Concrete Printed Exterior Finishes?

Consistency

A factory pre-blended stucco is the proper blend of cement, lime, sand, and other additives like fibers proportioned consistently from batch to batch. Factory pre-blend stucco is also computer weigh batched for accuracy and documented at the plant for quality control. Factory pre-blended stucco also eliminates the need and guesswork of adding extra water or dry ingredients during the field mixing process that can skew the material proportions and cause stucco to crack, not bond well or experience other performance failures. That’s the consistency needed to finish the exterior walls on a 3-D concrete printed structure. 

Speed and Strength 

Speed is another advantage of pre-blended stucco as part of the 3-D printing concrete construction system. Consider that Contour Crafting Corporation and QUIKRETE anticipate the ability to produce a 2,000 square-foot house in a few days, not weeks, for a fraction of the cost of traditional construction using their proprietary 3-D printing technology and concrete. With other 3-D printing concrete technology systems projecting similar capabilities, pre-blended stucco is arguably the only exterior finish that will keep up with the rapid rate of construction while delivering high-quality results. 

The layer on layer concrete wall created through the 3-D printing process provides the ideal surface for applying pre-blended stucco as a single base coat without reinforcing metal lath. The ridges in the wall allow the contractor to skip the scratch coat and scoring the surface so they can immediately apply a thin base coat and finish coat directly to the 3-D printed concrete wall. Once the stucco is applied, it embeds the ridges on the concrete wall to create a strong, monolithic, almost permanent bond with the wall. 

Consequently, the bond strength between the stucco layer and a concrete wall is higher than over a wood or metal lathed surface. For contractors looking to further complement the automated construction process, spray-applying a pump-grade pre-blended stucco over 3-D printed concrete walls is the way to go. That’s the speed and strength needed to finish the exterior walls on a 3-D concrete printed structure.

Flexibility

Factory pre-blend stucco is formulated with the right proportion of cement, sand, lime, and other chemical additives to provide the best workability for the contractor. As needed, pre-blended stucco can also be upgraded with shrinkage reducing agents, fibers and hydrophobic water repellents to help protect the exterior finish from cracking, staining, fading or being otherwise harmed over time. Available in 80-pound bags and 3,000-pound bulk bags that can be pumped or hand-applied, pre-blended stucco can accommodate the size or type of any project without requiring an excessive staging area. That’s the flexibility needed to finish any exterior wall including those on a 3-D concrete printed structure. 

Efficiency

Labor is the greatest cost in a wall assembly at about 50 percent with the other components like substrate, lathe, insulation and stucco accounting for the difference. The stucco material actually only represents about 6 percent to 8 percent of the cost for the total wall system. So, with no lathe and reduced installation labor, using pre-blended stucco for the wall finish is the way to go. With the support of a reputable manufacturer, reliable technical resources and a skilled team applying the stucco, contractors can spend more time focusing on other opportunities rather than being held hostage to a pile of sand and field mixing. That’s the efficiency needed to finish the exterior walls on a 3-D concrete printed structure. 

Responsibility 

An often overlooked value of 3-D printed concrete construction is the environmental benefits. With less material waste and energy usage, 3-D printed concrete is a responsible approach to construction. Using factory pre-blended stucco from a silo system with reusable bulk bags helps reduce material waste and fewer paper bags in landfills. In addition, factory pre-blended stucco is produced regionally, which helps manage transportation costs and positively contributes LEED certification efforts. Also, there is no concern with sand run-off from piles in the field mixing process that often requires a containment barrier to prevent the contamination of sewer systems by many municipalities. That’s the responsible approach needed to finish the exterior walls on a 3-D concrete printed structure.

The reality of 3-D printing concrete to build high-quality customized structures fast, efficient and affordable is not far from becoming a common industry practice. When that happens, factory pre-blended stucco is the only exterior finishing material that lives up to the same value proposition. In fact, it’s highly possible that someday pre-blended stucco will be spray-applied over both exterior and interior 3-D printed concrete walls using the same technology and equipment. For stucco and plastering professionals prepared, the evolution of 3-D printed concrete structures could mean more projects, greater profitability and substantial overall growth in business.