While EIFS (Exterior Insulation and Finish Systems) exterior cladding and stucco may have a very similar appearance, the composition of these is different. The EIFS cladding, with several insulating and moisture-draining layers beneath, consists of polymeric-bonded aggregate and reinforced cement. Stucco, on the other hand, is a centuries-old material made from Portland cement and lime bonded with sand and water.
While the materials in EIFs or stucco are different, eventually aging, drying, and building movement can cause cracks in either material. The essential objective is to keep the amount of cracking over time in either material to a minimum.
Mitigating Cracking in EIFS Cladding
Surface cracks will eventually develop in the EIFS lamina or coating. The cause may be from hygric (moisture) or thermal stresses or a combination of both. The EIFS layering is supported by a mesh reinforcement that essentially redistributes the stress throughout the coating and allows minute micro-fractures to form rather than large visible cracks. Stucco does not have this built-in mitigation.
Over time, continued exposure to moisture will weaken the mesh material. This influence eventually reduces the elasticity of the mesh and can cause the mesh itself to crack. Usually the cracking first occurs near window openings where moisture may most likely accumulate.
Effects of Building Movement
Buildings move over time. Taller buildings are more likely to shift, though shorter ones do also. In some case, control joints are part of the design to minimize the stress from movement or shifting. When these are built into the structure, the stress from the movement will reduce cracking in either EIFS or stucco.
When EIFS are incorporated in a wood frame building, the stresses of movement from humidity and drying are absorbed by the wood members in a cross-grain fashion. According to Building Science.com, builders concentrate cross-grain wood elements at rim joists, around heavy framing, and top and bottom plates to respond to humidity changes.
EIFS or Stucco
EIFS is an effective energy managing and money-saving option for many types of structures. However, moisture and humidity management are essential to minimize cracking from humidity and accumulated moisture. The latest EIFS systems address these challenges by integrating moisture eliminating cavities and materials.