![]() ![]() ![]() Pre-blended materials are also good for the environment as there is no need for a sand pile on the ground, which also eliminates ground contamination getting into the material (reducing the risk of efflorescence). The applicator has only to add the proper amount of water. The benefit of pre-blended stucco is that the proper proportions of the constituents of the mix cement, lime, sand and fibers when specified are pre-measured at the factory. The above mentioned materials and their respective systems, whether the selection is for a traditional three-coat or one-coat stucco system are now available as pre-blended materials. One-coat stuccoes without an ESR number have not been through the compliance of AC 11 and therefore the risk is that they would not be code compliant. The selected material will also have an ESR that can be used for reference of compliance. The material selected will also indicate that the material complies with AC 11 by having an ESR number posted on the packaging. The ESR number will refer to a report that verifies that the material selected has been tested and complies with the Acceptance Criteria of AC 11. When one-coat proprietary stucco is specified, make sure the material you are using has an Evaluation Service Report number. Another benefit is that one-coat stucco is a method of installation that should make stucco applications much easier to comply with the new ASHRAE 90.1 energy standard since the base coats are much lighter and thinner by virtue of the 3/8- to 1/2- nominal thicknesses, reducing the weight of the stucco assembly when applied over extruded or expanded polystyrene insulation to meet the requirements of ASHRAE 90.1. One-coat stucco is quicker to apply using a reduced amount of material and labor. ![]() The one-coat stucco properties evaluated are structural, durability, fire resistance ratings and the types of construction (I through IV non-combustible construction) the material can be installed on. Typical one-coat stucco materials that go through the process to comply to Acceptance Criteria for Cementitious Exterior Wall Coatingshave additional crack inhibiting fibers and proprietary ingredients that reduce or minimize shrinkage cracking. There are some advantages to installing one-coat proprietary systems. All such alternate systems require a special evaluation service report based upon Acceptance Criteria for Cementitious Exterior Wall Coatings, published by the International Code Council. These one-coat systems can incorporate tongue and groove insulation board over sheathing or open framing. These systems are proprietary and were developed due to the energy crisis of the seventies where buildings in the Southwestern part of the United States were required to increase the R value of all exterior walls. One-coat System:A non-traditional stucco systems which does not meet the above ASTM standard and is considered by the International Building Code as an alternative wall cladding. Two-coat Stucco (ASTM C 926): Typically over a solid plaster base of unit masonry or pre-cast or cast in place concrete with a 3/8-inch scratch, 1/8-inch brown and 1/8-inch finish coat for a total thickness of 5/8-inch (applied directly to the solid plaster base without lath).īoth three-coat and two-coat ASTM C 926 stucco applications are recognized in the building code and have a long track record of successful applications. ![]()
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