The advantages of pre-blended stucco materials and material delivery systems can be broken down into five basic categories; quality, consistency, safety, environmental, and efficiency. Here is a breakdown of the five categories, showing how each can contribute to sound construction practices that should equate to providing some insight on how that can correlate to increased efficiency and revenue.


Quality starts with the manufacturing process. To provide good products, you must start with high-quality raw materials. Proper selection of cement, lime, aggregate and other constituents is critical to providing a quality product. The raw materials all need to comply with the necessary ASTM standards and the components that go into a stucco mix all have an ASTM standard that are applicable to each. Once the proper raw materials are sourced along with the optimal percentage of each material, you then develop a mix design or formula by which to produce. The most overlooked raw material that goes into a stucco mix is the aggregate. A proper gradation of the aggregate is the backbone to quality stucco.

The advantage to pre-blended stucco is the ability of the manufacturer to properly dry the aggregates and provide a quality aggregate that complies with ASTM C 897 (Standard Specification for Aggregate for Job Mixed Portland Cement Plaster) or ASTM C 144 (Standard Specification for Aggregate for Masonry Mortar)-ASTM C 897 is the preferred plaster aggregate. A dependable gradation of aggregate-along with consistent cement to aggregate ratio-gives you a quality product that is equally good from batch to batch. Consistent aggregate gradations also contribute to the minimization of the amount of cracking and/or crazing that naturally occurs in stucco.

Stucco that has minimal shrinkage cracking gives you a better stucco wall and also reduces the amount of moisture that can enter the wall assembly. A high-quality product also allows the crew to keep moving and increases their productivity, as they have to spend less time adjusting batches on the ground or wall.

Another benefit is that the silo delivery systems and the recyclable bulk bags protect the product from exposure to contaminants, weather and debris, which helps to control efflorescence and other variables that could decrease the integrity of the stucco.


Consistency of the actual stucco mix is another key element for selecting a pre-blended stucco product. Whether the product comes to the job site in a 3,000 pound bulk bag, to be used with a material delivery system (silo) or an 80-pound paper bag, knowing that you have the proper ratio of the raw materials, along with a consistent gradation of aggregate, ensures that the product will be the same from batch to batch. Because the aggregate in the mix is dried, you are assured that the correct (optimal) amount of aggregate is added to each batch throughout the day. Aggregates with different moisture contents can result in different volumes and weights; thus, making it difficult to proportion in a mix consistently.

Using pre-blended stucco products minimizes the human element for error from the mixing station, as the laborer needs only to add the proper amount of water to the mix. When using a silo delivery system, it is only a matter of pulling a lever to dispense the material into the mixer and if using 80-pound bags, it is a matter of breaking bags into the mixer. Monitoring inconsistent shovels of sand in the morning and afternoon or after a heavy rainfall is no longer a concern.

The consistency of the pre-blended stucco product also gives the owner piece of mind as there is a computer-generated batch ticket that shows what went into the batch at the manufacturing facility every time.


There is also a direct relationship with using pre-blended stucco and maintaining a safe worksite. Pre-blended stucco products reduce the strain on the laborers’ back, as the amount of shoveling that he or she does each day is eliminated. Each silo is engineered to increase job site productivity and safety by making the laborer more efficient at the mixing station. Field mixing in general, and shoveling sand, requires a lot of twisting and turning along with heavy lifting, all of which are recipes for back injuries. Using silo delivery systems with pre-blended products eliminates the risk of job-related injuries and can ultimately lower a contractor’s workers’ compensation rating.


Utilizing a silo system also lends itself to the changing regulations we all work in as it relates to being conscious of the impact we have on the environment. The recyclable bulk bags used with the silo delivery systems are used on the site and returned to the manufacturing plant to be reused several times until they ultimately expire and are then recycled into different products. More and more areas of the country are no longer allowing sand piles on projects unless they are confined or contained to a specific area or containment unit to eliminate sand run-off into streets or drain sewers. Since pre-blended and packaged stucco already contains the aggregate, there are no piles that can contaminate the soil or become wasted. Wasting sand through the use of a sand pile is a terrible use of a valuable natural resource.

Pre-blended stucco eliminates tens of millions of empty paper bags each year. Efficiency is another benefit that is derived from using pre-blended stucco products, especially when using a silo delivery system. Silo delivery systems range in size from the ability to hold one 3,000-pound bulk bag (a cubic yard) up to ten (10 cubic yards) 3,000-pound bulk bags. The time to mix a typical batch of stucco from a silo delivery system is cut in half, saving the contractor thousands of dollars in labor costs.

In some cases, with new wet-mix technology, the labor cost to mix is essentially eliminated. Consistent high-quality stucco, batch to batch, also makes the plasterer more efficient as they get down the wall faster, saving the contractor significant application costs. 


Silos are versatile and easily adapt to the diverse needs stucco contractors have working on any site. The portable silos and bulk bags require no special equipment, only a standard forklift to lift and dispense the 3,000-pound bulk bag or relocate the silo on site. Ranging in size from a 4-foot-by-5-foot pallet sized footprint to an 8-foot-by-11-foot sized footprint, a silo allows any contractor to use less space than traditional mixing stations. Since space is a premium on most sites, using silo delivery systems in tight quarters is very desirable. The dry, pre-blended material allows contractors work to continue through all seasons, keeping the stucco contractor productive year round.

The five combined benefits of pre-blended stucco allow the plastering contractor to increase the revenue generated on a project while adopting sound and sustainable construction practices. Pre-blended stucco products also offer the architect, building owner and the general contractor some piece of mind that the stucco product being installed is factory produced and is consistent from batch to batch. Pre-blended stucco products are being specified more frequently than in the past and we see that increasing in the future. W&C