Exterior Insulation Finishing System

From Wikipedia, the free encyclopedia

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (January 2007)

Exterior Insulation and Finish Systems ("EIFS") are a type of building product that provides exterior walls with an insulated finished surface, and waterproofing in an integrated composite material system.

Contents 1 Terminology 2 How EIFS are used 3 How EIFS are installed 4 Composition and types of EIFS 5 History of EIFS 6 Marketing of EIFS and The EIFS Industry 7 References

[edit] Terminology

Although often called "synthetic stucco", EIFS is not 'stucco' in the sense of the word stucco. Traditional stucco is often called Portland Cement Plaster, and is a centuries-old non-insulating material. Stucco consists of sand, Portland Cement, and water, and is a hard, dense, thick, non-insulating material. EIFS is a modern, lightweight synthetic wall cladding that includes foam plastic insulation and thin synthetic coatings. There are also specialty stuccos that use synthetic materials but no insulation, and these are also not EIFS either. A common example is what is called one-coat stucco, which is a thick, synethic stucco applied in a single layer (traditional stucco is applied in 3 layers). There is also an EIFS-like product called a Direct-Applied Finish System (or DAFS), which is essentially an EIFS but without the insulation - this product is also not EIFS either, and has quite different characteristics.

EIFS are proprietary systems of a particular EIFS producer and consist of specific components. EIFS are not generic products made from common separate materials. To function properly, EIFS needs to be architecturally designed and installed as a system.

There are a number of versions of EIFS, as described below. The most basic and common EIFS is called a barrier EIFS (also known as a traditional or conventional EIFS). Another type is called an EIFS with Drainage, which is a barrier EIFS to which a water drainage capability has been added.

A basic EIFS includes only the insulation and EIFS materials (coatings, adhesives, etc.). Other types of EIFS may also include plastic edge trim, water-resistive barriers, a drainage cavity, and other accessories. The technical definition of "an EIFS" does not include wall framing, sheathing, flashings, caulking, water barriers, windows, doors, and other wall components. However, as of recently, architects have begun specifying flashings, sealants, and wiring fasteners (such as Viperstrap) as being a part of the EIFS scope of work, essentially requiring EIFS contractors to carry out that work as well. The technical national consensus standard for the definition of an EIFS, as published by ASTM International organization, does not include flashing or sealants as part of the EIFS.

[edit] How EIFS are used

EIFS can be used on a wide range of buildings, including homes, apartments, condominiums, high-rise buildings, offices, malls, shopping centers, hotels, motels, clinics, government buildings, and so on. It can also be used to create facades and soffits on shopping centers, and for decorative purposes (to look like stone, or to create signage or artwork). EIFS is not a roofing material.

EIFS can be used on new buildings and also can be installed on existing walls, called "retrofitting", to upgrade the appearance and provide insulation, without affecting the activities indoors during the renovation (EIFS is installed completely from the outside of the building).

EIFS has a number of features that contribute to its popularity, including a modern seamless look, the ability to mimic other materials, reasonable cost, and high energy efficiency. EIFS looks like traditional stucco or concrete, and is very common through North America.

The use of EIFS is regulated by the building codes. However, since EIFS is a relatively new type of wall cladding, many codes do not refer to EIFS by name. EIFS is generally regulated by Evaluation Reports ("ER's") which are technical reports issued by code agencies for a specific product. The ER's go into great detail about how a specific EIFS product can be used. The primary source of ER's in the USA is the Evaluation Services division of the International Code Council.

[edit] How EIFS are installed

EIFS is attached to the outside face of exterior walls with an adhesive, mechanical anchors (screws and washers), or both. The supporting wall surface is continuous (not "open framing") and flat, and can be a solid material, or some type of sheathing that is attached to studs. The surface to which an EIFS is applied is called the substrate. Common substrates include concrete, cinder block, brick, cement board sheathing, Dens Glass Gold, exterior grade gypsum sheathing, glass fiber-faced gypsum sheathing, oriented-strand board (OSB), and plywood.

EIFS is usually installed at the construction site by hand by independent professional plastering contractors; EIFS producers do not install EIFS products. EIFS is not a do-it-yourself product - it is not sold through retail stores.

EIFS can also be made as prefabricated panels. The panels are made in a factory and have a lightweight welded metal subframe. When completed they are trucked to the building site, raised with a crane, and attached to the building frame.

[edit] Composition and types of EIFS

EIFS consists of a number of layers that are installed in the following order. The most basic EIFS (a barrier EIFS) consists of 3 layers:

• A layer of foam plastic insulation (also called simply "foam") that comes in the form of sheets 2' x 4'. If an adhesive is used to attach the insulation, the adhesive is applied to the foam with a trowel. Most EIFS use a type of insulation called Expanded Polystyrene, also known as EPS. EPS is 1 lb. density Expanded Polystyrene, similar to the white foam that coffee cups are made of. The usual range of thickness for EIFS insulation is 3/4" to 4", although thicker pieces are sometimes used for decoration accents - called foam shapes.

• A reinforced layer that is applied onto the face of the insulation with a trowel, consisting of a fiberglass reinforcing mesh ( or "mesh") embedded in a cementitous adhesive. The mesh has an open weave, somewhat like window screening but with opening about 1/4" square. It is made of fiberglass and can be cut with a utility knife. The mesh is available in various weights, the "heaviness" determines the impact strength of the surface (resistance to damage by being "hit"). The standard weight is 4oz, the high-impact mesh weight goes up to 15 or 20oz. This 2-part layer is called the Base Coat.

• A final topcoat,or finish, which is a colored, textured paint-like material that is applied with a trowel or, very rarely, by spraying. A wide range of colors and textures are available as well as custom colors. Available textures include smooth surfaces, rough "stucco-like" textures, embedded stone chips, multi-color (granite-like mixtures,) and even brick-like treatments. This layer is called the finish. It is acquired by floating.

If an EIFS with Drainage, or water-managed EIFS is installed, a water resistive barrier (aka a WRB) is first installed over the substrate (generally Dens Glas Gold, exterior-grade gypsum sheathing, OSB or plywood). The moisture barrier is applied to the entire wall surface with a mesh tape over joints and a liquid-applied membrane or a protective wrap like Tyvek or felt paper. Then a drainage cavity is created (usually by adding some sort of space between the foam and the WRB). Then the other 3 layers, described above, are added. This type of EIFS is required by many building codes areas on wood frame construction, and is intended to provide a path for incidental water that may get behind the EIFS with a safe route back to the outside. The purpose is to preclude water from damaging the supporting wall.

Adhesives and Finishes are water-based, and thus must be installed at temperatures well above freezing. Two types of Adhesives are used with EIFS: those that contain Portland Cement ("cementitious"), or do not have any Portland Cement ("cementless"). Adhesives that contain Portland Cement harden by the chemical reaction of the cement with water. Adhesives and Finishes that are cementless harden by the evaporation of water - like house paint. Adhesives come in two forms. The most common is in a plastic pail as a paste, to which Portland Cement is added. Adhesives are also available as dry powders in sacks, to which water is added. Finishes come in a plastic pail, ready to use, like paint. EIFS insulation comes in individual pieces, usually 2' x 4', in large bags. The pieces are trimmed to fit the wall at the construction site.

[edit] History of EIFS

EIFS was developed in Europe after World War II and was initially used to retrofit solid masonry walls. EIFS started to be used in North America in the 1960s, and became very popular in the mid- 1970's due to the oil embargo and the resultant surge in interest in high energy efficiency wall systems (such as EIFS provides). The use of EIFS over stud-and-sheathing framing (instead of over soils walls) is a North American technique. EIFS is now used all over North America, and also in many others areas around the world, especially in Europe and the Pacific Rim.

In North America, EIFS was initially used almost exclusively on commercial buildings. As the market grew, prices dropped to the point where its use became widespread on normal single family homes.

In the late 1980s problems started developing due to water leakage in EIFS-clad homes. This created a national controversy and numerous lawsuits. While not inherently more prone to water penetration than other exterior finishes, critics argue that barrier-type EIFS systems (non-water-managed systems) do not allow water that may penetrate the building envelope to escape.^[1]

The EIFS industry has consistently maintained that the EIFS itself was not leaking, but rather poor craftsmanship and bad architectural detailing at the perimeter of the EIFS was what was causing the problems. The building codes reacted by mandating EIFS with Drainage on wood frame building and additional on-site inspection. Most homeowner insurance policies cover EIFS and EIFS-like systems.

It should be noted that insurance companies like Factory Mutual may not provide fire insurance coverage to clients who install EIFS exterior building systems, due to the lack of adequate fire-resistance inherant in the materials. Also, some facility owners have found that EIFS systems that are installed at lower building levels are subject to vandalism as the material is soft and can be chipped or carved resulting in significant damage.

[edit] Marketing of EIFS and The EIFS Industry

EIFS accounts for about 10% of the US commercial wall cladding market. There are several dozen EIFS producers in North America. Some sell nationwide, and some are regional in their area of business operations. The EIFS producers sell the various system components (adhesives, coatings, etc.) through specialty building product distributors who in turn resell the components to local EIFS installers. The top 6 EIFS producers account for about 90% of the US market.

[edit] References