Consider a building with concrete masonry units as a base, but then the sheathing transitions to glass-mat gypsum or plywood sheathing on the upper levels. Specifiers can select a single fluid-applied AWB for these different substrates, and they are also effective under multiple types of cladding, such as stucco, cement board, wood, vinyl, brick, stone, and metal panels. While the consistency of the fluid application may need to be adjusted, depending on the cladding above or below the substrate, a singular product as part of a tested system ensures greater reliability and less complexity. The fluid-applied AWB forms a bond with the wall sheathing and can act as a waterproof barrier when combined with a joint and rough opening treatment.
When it comes to the thermal barrier, EIFS systems on a building deliver the greatest R-value and overall energy performance. The American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) defines ci as “continuous across all structural members without thermal bridges other than fasteners and service openings.”1
Thermally insulating the wall structure with EIFS wraps the building in a thick, well-insulated, and protective blanket. This eliminates thermal bridging, which keeps the wall structure warm and dry. Using the system on the outside of the wall maintains the temperature of the building wall structure above the dew point, effectively dealing with the potential for condensation caused by water vapour diffusion.
Advancements in material science now deliver thermal barriers for the exterior wall, providing even greater fire protection. Mineral wool insulation which is noncombustible, inorganic, and mould-retardant can resist fire and temperatures in excess of 1093 C (2000 F). When mineral wool serves as the thermal barrier in a fully engineered assembly, it also allows the vapour barrier to do its job without creating additional traps for moisture in the
wall cavity.
Extruded polystyrene (XPS is also commonly used with EIFS and provides a higher r-value per inch than mineral wool—5 vs 4.3—and has a higher compressive strength. However, while being vapour permeable, it has a much lower water vapour permeance rating, as per ASTM E96, Standard Test Methods for Water Vapor Transmission of Materials. It goes up to 1.5, while mineral wool can go up to 50 or higher. Choosing the right insulation will depend on the performance required by the designer.
Exterior facade cladding
Using EIFS on the wall assembly broadens the range of possibilities for the exterior facade cladding. Rather than being limited to delivering a textured, stucco-looking esthetic, architects and designers can paint with a broad brush. They can combine the traditional looks of brick, stone, concrete, and stucco with the modern appeal of metal, wood, and tile. For example, architects may choose to create the look of brick or wood over EIFS by employing resin-cast shapes. This approach maintains the timeless look of traditional brick or wood without having construction crews lay brick and mortar or cut and ship lumber. It creates an authentic-looking facade, capitalizing on the latest material science. Even the discerning eye has difficulty determining if the material used is not traditional brick or wood.
Resin-cast bricks and wood can be made to match traditional textures and colours while creating unique looks. Compared to their predecessors, resin-cast brick and wood require little maintenance. They will not warp, crack, or chip, and are not prone to efflorescence. For increased UV resistance and hydrophobicity, they can be enhanced with a wide variety of coatings as well.
The possibilities do not end with resin-cast shapes; architects can also achieve the look of brick, wood, concrete, stone, metal, and other materials using trowel-applied acrylic finishes or a variety of other exterior coatings. The result is a more durable surface delivering the desired esthetic.
Coating and finishes
Using an engineered building enclosure system for the exterior wall can also take advantage of the wide variety of coatings available to the architect, whether the cladding is made of metal, resin-cast shapes, or other materials. With today’s advancements, these coatings can deliver strong visual impact while improving the durability of the exterior wall.
For instance, certain finishes applied over the surface of the exterior cladding can dramatically improve the performance of the facade. Hydrophobic finishes repel water, keeping walls cleaner longer, and providing greater protection against algae and mildew without sacrificing design possibilities, while super-hydrophobic finishes have self-cleaning capabilities with superior algae and mildew resistance.
