Flashing and Building Envelope Design
These comments are for general information only and are not intended to be relied upon as a guide for design, construction, or inspection of EIFS. Although every effort is made to ensure that this information is timely and correct, the responsibility remains with the designer, specifier, homebuilder, general contractor, and/or installer for specific applications. The specification, design, and construction of all EIFS must comply with local building codes and standards, applicable compliance reports and the individual manufacturer's system requirements. The successful performance of EIFS cladding is dependent upon the proper design and construction of the adjacent materials and systems of the structure.
Is flashing required with EIFS?
Yes. As with all wall cladding, flashing is an important component required by building codes. At points where water can enter the wall it should be directed to the exterior face of the cladding with flashing. Transition areas such as decks or roof/wall intersections are typical areas where flashing must be installed. Openings for windows and similar through-wall penetrations require jamb, head, and sill flashing to direct water to the exterior face of the cladding.
Note: Complete moisture protection requires rough opening protection and the integration of air seals, sealants, and flashings.
What are the most common entry points for water in building envelope walls?
As with all claddings, the most common water entry points in a wall are through or around windows, transitions from roof to walls, and transition from wall claddings to doors and chimneys. This coupled with improperly installed or missing flashing and sealants, can allow water to penetrate behind EIFS, or any other cladding, and into the wall cavity, where it can potentially cause moisture damage.
Some of these problems are inherent in the components themselves and other result from incorrect installation practices.
Is EIFS more vulnerable to damage from moisture intrusion than other wall claddings?
No. Moisture intrusion is a potential threat to durability of materials in wall construction, regardless of cladding type. Moisture intrusion should be avoided by following sound design and construction practices mandated by building codes.
Are EIFS vapor permeable?
Yes, but depending on the manufacturer and the product selected, the EIFS vapor permeability may vary. When requested, the EIFS manufacturers can perform a Water Vapor Transmission Test for specific walls to evaluate the tendency for condensation to occur.
What is "EIFS with drainage"?
EIFS with drainage is conventional EIFS installed over a water-resistive barrier, with provisions for discharging of incidental water that may enter behind the insulation board. In the event of a breach of the EIFS, the drainage path for moisture exists behind the EIFS to drain water to the exterior.
Note: EIFS with drainage is not meant to accommodate rainwater that penetrates through other components of construction. Flashing is required where rainwater may penetrate other components and at the interface of different components.
Is a water-resistive barrier required prior to installing EIFS in residential construction?
EIFS manufacturers recommend the use of water-resistive barriers over moisture sensitive substrates to provide additional protection in the event of a component failure. Local building codes will stipulate whether this is a requirement or not.