Over the years, variations of this system have been developed. The insulation typically consists of closed expanded polystyrene EPS and can be either adhesively or mechanically attached to the sheathing. The insulation typically consists of extruded expanded polystyrene XPS and is mechanically attached to the sheathing and or wall structure. EIFS is available in two basic types: a barrier wall system or a wall drainage system.
Barrier EIFS wall systems rely primarily on the base coat portion of the exterior skin to resist water penetration. Therefore, all other components of the exterior wall must either be barrier type systems or be properly sealed and flashed to prevent water from migrating behind the EIFS and into the underlying walls or interiors. Wall drainage EIFS systems are similar to cavity walls; they are installed over a weather barrier behind the insulation that acts as a secondary drainage plane.
The weather barrier must be properly flashed and coordinated with all other portions of the exterior wall to prevent water from migrating into the underlying walls or interiors. All EIFS are proprietary systems and the components of the system should not be modified beyond the limits stated in the manufacturer's literature.
The design of the interface with other components of the wall system is the responsibility of the wall designer. Details should make clear the design of the final construction.
If necessary, the sequence by which the wall assembly is to be constructed is addressed in the details. In general, construction conditions of the EIFS that should be detailed if they exist on the building include terminations, openings, joints, objects mounted onto the surface and special treatments to the surface.
The popularity of EIFS comes from its insulating qualities to reduce thermal loads on the exterior building wall and the light weight, low cost, and the ability of the system to be sculpted into shapes and patterns to achieve different aesthetic effects. The thermal performance of the exterior insulation is based on the thickness of the insulation selected. Problems observed with in-service EIFS installations are primarily related to moisture intrusion.
EIFS provides protection against moisture infiltration at the base coat; however, moisture migration through openings for windows, flashings and other items, or holes and cracks in the EIFS itself, have allowed leakage to occur on EIFS clad buildings. With barrier EIFS installations, or where weather barriers and flashing are improperly installed in conjunction with wall drainage EIFS installations, moisture has entered the wall system at these locations and caused damage to the wall sheathing and framing.
The extent of these occurrences on wood frame structures has led to class action lawsuits. EIFS finish coats come in a wide variety of colors and textures similar to those of stucco.
Backwrapping with Reinforcing Mesh A reinforcing mesh is attached to the substrate with the adhesive. When applying the boards, try to eliminate any gaps or thermal breaks between each piece. The insulation boards should be cut with a knife using a T-square to guide the cut. Installing the Insulation Boards Place the boards so there is no space between them to create breaks. After installation, check for any breaks or spaces.
If there are any, even the width of a credit card, they must be filled with an insulating material. Rasping Rasp the entire insulation board surface, not just the joints, with sandpaper to ensure they are level and smooth. Base Coat and Mesh Application Apply a prescribed base coat to prevent sunlight from affecting the insulation board surface. Several Sto-approved base coat products are acceptable. The mesh is then embedded until it is no longer visible through the base coat.
If the mesh does show through, more base coat is necessary to cover it completely. Allow the base coat to dry. Primer may be used here for complete protection.
Finish Coating Apply the finish coat directly over the base coat in continuous application. Floating or Spraying Textures Texture can be applied to the outer surface with various products and application methods. Sto offers stucco , limestone, various other textures to cover the EIFS. Sealant The final protective step is the application of a sealant to any joints where the EPS boards may meet another surface like a doorframe or meter box. The sealant acts as a shock absorber between the two surfaces, stretching as the surfaces move.
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