eifs & stucco
Exterior Insulation and Finish Systems
Exterior insulation and finish system (EIFS) is a general class of non-load bearing building cladding systems that provides exterior walls with an insulated, water-resistant, finished surface in an integrated composite material system. In Europe, systems similar to EIFS are known as External Wall Insulation System (EWIS) and External Thermal Insulation Cladding System (ETICS).
EIFS has been in use since the 1960s in North America, first on masonry buildings, but since the 1990s the majority on wood framed buildings. There is a history of water infiltration problems causing damage to buildings resulting in costly legal cases, so the recommended systems include a drainage plane to let water drain down and out from behind the cladding.
EIFS with Drainage, another EIFS system, is the predominate method of EIFS applied today. As the name implies, EIFS with Drainage helps to eliminate moisture before it has an opportunity to enter the wall cavity.
Exterior Insulation and Finish Systems (EIFS) and typically consist of the following components:
An optional water-resistive barrier (WRB) that covers the substrate
A drainage plane between the WRB and the insulation board that is most commonly achieved with vertical ribbons of adhesive applied over the WRB
Insulation board typically made of expanded polystyrene (EPS) which is secured with an adhesive or mechanically to the substrate
Glass-fiber reinforcing mesh embedded in the base coat
A water-resistant base coat that is applied on top of the insulation to serve as a weather barrier
A finish coat that typically uses colorfast and crack-resistant acrylic co-polymer technology.
Exterior Insulation and Finish Systems are one of the most tested and well researched claddings in the construction industry. Research, conducted by the Oak Ridge National Laboratory and supported by the Department of Energy, has validated that EIFS are the "best performing cladding" in relation to thermal and moisture control when compared to brick, stucco, and cementitious fiberboard siding.
In addition EIFS is in full compliance with modern building codes which emphasize energy conservation through the use of CI (continuous insulation) and a continuous air barrier. Both these components are built into today's EIFS products to provide maximum energy savings, and reduced environmental impact over the life of the structure. Along with these functional advantages come virtually unlimited color, texture, and decorative choices to enhance curb appeal and enjoyment of almost any home or structure.
Exterior Insulation and Finish Systems Benefits
EIFS can reduce air infiltration by as much as 55% compared to standard brick or wood construction. And since walls are one of the greatest areas of heat and air conditioning loss, improvement in the wall insulation can be very meaningful in terms of energy conservation.
What's more, EIFS add to the "R-value" of a home or building. (R-value is a measurement of the resistance to heat flow; the higher the R-value, the better the material's insulating value.) Most EIFS use insulation board with an R-value of R-4 to R-5.6 per inch as the innermost layer in the wall system. When combined with standard wall cavity insulation, this extra layer can boost wall insulation from R-11 to R-16 or more.
EIFS was the first to meet standards of Continuous Insulation (CI) and has long been the solution to the expanded requirements.
There are a variety of case studies available validating the energy savings associated with EIFS; for a recent example of EIFS in action, you can check out the 2012 Better Buildings Federal Awards Program results, where an EIFS cladded building helped reduce energy use by nearly 45% in a 12 month period.
EIFS also have excellent resistance to dirt, mildew and mold, which helps keep the building exterior looking clean and freshly painted. Should the surface ever become soiled, it can usually be cleaned by hosing it down.
The systems are designed to be very flexible, which makes them highly crack resistant. When walls expand or contract due to rising or falling temperatures, EIFS are resilient enough to "absorb" building movement and thus avoid the unsightly cracking problems that are so common with stucco, concrete and brick exteriors.
Design flexibilty / Aesthetic colour texture
The rich appearance of EIFS bears a resemblance to stucco or stone, but the systems are far more versatile than these and other materials. Not only do EIFS come in virtually limitless colors and a wide variety of textures, but they also can be fashioned into virtually any shape or design.
With EIFS, skilled applicators can create all sorts of exterior architectural detailing that would often be cost-prohibitive using conventional construction -- cornices, arches, columns, keystones, cornerstones, special moldings and decorative accents are but a few examples. Using this ingenious process, EIFS applicators can give a striking, distinctive appearance to any building or residence.
Recent research, conducted by the Oak Ridge National Laboratory and supported by the Department of Energy, has validated that EIFS are the "best performing cladding" in relation to thermal and moisture control when compared to brick, stucco, and cementitious fiberboard (commonly known as fiber cement) siding.
EIFS are among the most water resistant exterior surfaces you can put on a house. But as with all claddings, EIFS must be correctly installed and properly detailed if they are to perform properly. Otherwise, moisture can get behind the systems and cause damage, just as it can with wood siding, brick or any other exterior.
Water intrusion is seldom a problem on commercial structures with EIFS. Water intrusion damage to homes is uncommon, but when it does occur, the moisture typically affects only small areas which can be easily and inexpensively repaired.
EIFS have passed the major fire resistance tests that are required by the building codes. EIFS have passed fire resistance, ignitability, intermediate multi-story, and full scale multi-story corner tests; meeting the standards set forth with each test. These tests include:
Fire Resistance (ASTM E 119) – EIFS PASSED, showing no negative effect on the fire resistance of a rated wall assembly.
Ignitability (NFPA 268) – EIFS PASSED with no ignition at 20 minutes of radiant heat exposure.
Intermediate Multi-Story Fire Test (NFPA 285 (UBC 26-9)) – EIFS PASSED
Criteria included resisting the spread of a flame within combustible core/component of panels from one story to the next. In addition, resisting lateral spreading of flames from the origin of the compartment fire to adjacent spaces.
Full Scale Multi-Story, corner test (ANSI FM 4880) – EIFS PASSED with NO height restrictions
As a building material, stucco is a durable, attractive, and weather-resistant wall covering. It was traditionally used as both an interior and exterior finish applied in one or two thin layers directly over a solid masonry, brick or stone surface. The finish coat usually contained an integral color and was typically textured for appearance.
Modern stucco is made of Portland cement, sand, and water. Lime is added to increase the permeability and workability of modern stucco. Sometimes additives such as acrylics and glass fibers are added to improve the structural properties of the stucco. This is usually done with what is considered a one-coat stucco system, as opposed to the traditional three-coat method.
stucco was adapted for this new use by adding a reinforcement lattice, or lath, attached to and spanning between the structural supports and by increasing the thickness and number of layers of the total system. The lath added support for the wet plaster and tensile strength to the brittle, cured stucco; while the increased thickness and number of layers helped control cracking.
The traditional application of stucco and lath occurs in three coats typically consist of the following components:
the scratch coat, the brown coat and the finish coat. The two base coats of plaster are either hand-applied or machine sprayed. The finish coat can be troweled smooth, hand-textured, floated to a sand finish or sprayed.
In exterior wall applications, the lath is installed over a weather-resistant asphalt-impregnated felt or paper sheet that protects the framing from the moisture that can pass through the porous stucco.
The final, exterior layer is the "finish coat", of which there are two recommended types:
Acrylic Finish, an acrylic-based finish from 1 to 4 mm (0.039 to 0.157 in) thick. It can be applied in many ways and can be ordered in any color.
Color Coat, a colored sand, cement, and lime mixed finish typically 3 mm (0.12 in) thick. It is applied over the second coat (brown coat) and can be floated with water for a sandy finish or textured over with a trowel to create various styles of finishes. Premixed, bagged stucco is gaining in use and is available in coarse graded sand and finer graded sand for creating a variety of troweled finishes; it is available in a variety of colors.
Aesthetic / Colour Texture / Durability
The texture for stucco is only limited by the designer’s imagination and the talent of the applicator. This makes stucco unique among the decorative finishing materials available to designers and builders. A nearly unlimited palette of colors is available in acrylic and cement finishes.
Portland cement plaster is a proven long-term value. ASTM STP 1269 rated cement stucco as the lowest net life cycle cost cladding.