Несущие системы наружной отделки зданий: EIFS (система наружной теплоизоляции и финишной отделки)

Non load bearing building cladding

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. EIFS has been in use since the 1960s in North America and was first used on masonry buildings. Since the 1990s, the majority of wood framed buildings have used EIFS.

EIFS was developed in Europe after World War II and was initially used to retrofit masonry walls. EIFS started to be used in North America in the 1960s, at first on commercial masonry buildings. EIFS became popular in the mid 1970s due to the oil embargo and the resultant surge in interest in insulating wall systems that conserve energy used for heating and cooling. Critics argue that, while not inherently more prone to water penetration than other exterior finishes, barrier type EIFS systems (non water managed systems) do not allow water that does penetrate the building to escape. The EIFS industry has consistently maintained that poor craftsmanship and bad architectural detailing at the perimeter of the EIFS was the problem. As a result, building codes began mandating a drainage system for EIFS systems on wood frame buildings and additional on site inspection. Though there are some cases where insurance companies may not offer coverage for EIFS, several companies do. EIFS systems installed at lower building levels are subject to vandalism, as the material is soft and can be chipped or carved resulting in significant damage. In these cases, heavier ounce reinforcing mesh can drastically increase the durability of the EIFS system. EIFS is now used all over North America, and in other areas around the world, especially in Europe and the Pacific Rim. The use of EIFS over stud and sheathing framing instead of over solid walls is a technique used primarily in North America. As of 1997 EIFS accounted for about 4% of the residential siding market and 12% of the commercial siding market. The predominant method of EIFS applied today is EIFS with Drainage, which provides a way for moisture accumulated in the wall cavity to evacuate. The technical definition of an EIFS does not include wall framing, sheathing, flashings, caulking, water barriers, windows, doors, and other wall components. However, some architects have begun specifying flashings, sealants, and wiring fasteners as being a part of the EIFS scope of work. Many of the EIFS manufacturers have their own standard details showing typical building conditions for window and door flashings, control joints, inside/outside corners, penetrations, and joints at dissimilar materials which should be followed for that manufacturer's warranty.

EIFS are typically attached to the outside face of exterior walls with an adhesive (cementitious or acrylic based) or mechanical fasteners. Adhesives are commonly used to attach EIFS to gypsum board, cement board, or concrete substrates. EIFS are attached with mechanical fasteners (specially designed for this application) when installed over house wraps (sheet good weather barriers) such as are commonly used over wood sheathings.

Research, conducted by the Oak Ridge National Laboratory and supported by the Department of Energy, has affirmed that EIFS are the "best performing cladding" in relation to thermal and moisture control when compared to brick, stucco, and cementitious fiberboard siding. EIFS are in compliance with modern building codes that emphasize energy conservation through the use of CI (continuous insulation) and a continuous air barrier. EIFS before 2000 were barrier systems, meaning that the EIFS itself was the weather barrier. After 2000, the EIFS industry introduced the air/moisture barrier that resides behind the foam. In a study done by the Department Of Energy's Office of Science Oak Ridge National Laboratory, it was found that the best air/moisture barrier was a fluid barrier. The Oak Ridge National Laboratory, ATLANTA, Oct. 28, 2006 — EIFS "outperformed all other walls in terms of moisture while maintaining superior thermal performance." The National Institute of Standards and Technology (NIST) has evaluated the five life cycle stages of the environmental impact of EIFS alongside brick, aluminum, stucco, vinyl, and cedar. Depending on a variety of site and project specific conditions, EIFS have the potential to save money in construction costs and contribute toward energy efficient operations and environmental responsibility when correctly designed and executed. Some types of EIFS have passed some fire tests that range from resistance to ignitability, that include: ASTM E 119, NFPA 268, NFPA 285. However, some types and thicknesses of EIFS have been involved in large uncontrolled exterior building fires, such as the 2008 Monte Carlo Hotel Casino fire.

EIFS systems have been the subject of several lawsuits in the United States, mostly related to the installation process and failure of the system causing moisture buildups and subsequent mold growth. The most notable case concerned the former San Martin, California courthouse. This case was settled for $12 million. The basic underlying problem behind EIFS litigation was that EIFS was marketed as a cost effective replacement for stucco. Stucco is expensive to install because it must be carefully applied by skilled craftsmen. General contractors switched to EIFS because they were supposed to be easy to install with unskilled or semi skilled labor and would not crack like traditional stucco. Although EIFS if properly installed according to the manufacturer's directions should not have water intrusion problems, many installers cut corners by using insufficiently trained labor and also failed to supervise their work adequately. In turn, thousands of EIFS installations were noncompliant and suffered severe water intrusion and mold as a result. While the EIFS industry has consistently tried to shift the blame to installing contractors, the construction industry has retorted that using journeymen carpenters in turn eliminates the cost advantage of EIFS over stucco, and that the EIFS industry should have anticipated this issue and engineered its products from the beginning to be installed by unskilled labor or semi skilled labor (that is, it should have been a fault tolerant design).

EIFS account for about 10% of the US commercial wall cladding market. There are several dozen EIFS manufacturers in North America. Some sell nationwide, and some are regional in their area of business operations. The top five EIFS producers account for about 90% of the US market. These producers include Dryvit Systems, STO Corp., BASF Wall Systems, Master Wall, and Parex.

EIFS offer the option of adding architectural details that are composed of the same materials. These mouldings come in a variety of shapes and sizes. They are widely used on residential and commercial projects in North America and are gaining popularity worldwide.