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The Real Facts About EIFS

- Dryvit's Patent -

From Dryvit Systems Inc. patent #5,363,621 for its Insulative wall cladding having insulation boards fitting together to form channels submitted January 28, 1993:

FIELD OF THE INVENTION

This invention relates to insulative cladding of walls of buildings, particularly to thermal and water-proof insulative cladding, and to insulation boards and battens of use in said cladding.

BACKGROUND TO THE INVENTION

Certain types of walls of buildings have an inner cavity between the outer cladding and an inner wall, typically consisting of a plasterboard material. The aforesaid cavity communicates with the outside atmosphere to provide an air pressure equalization chamber and water vent conduit for water ingressing through the outer cladding. Notwithstanding the high degree of care during construction to provide a water-impermeable, i.e., rain-fast, membrane to the outside cladding surface, over periods of time under the influence of wind and rain, temperature and frost and the like, hair-line cracks invariably are formed in the rain-fast layer to permit said ingress of moisture through the cladding to the cavity and into the interior of the building. Accordingly, the cavity must communicate with a weep or vent hole or channel to prevent build-up of water within the cavity.

In considering the desirability of a particular type of insulative cladding for use in a wall, regard must be had to the effect of wind pressure and rain on the outer wall. In the absence of direct communication between the outside atmosphere and the atmosphere inside the building and/or any cavity, significant air pressure differentials may exist dependent on the wind speed and the like. In consequence of this relatively large pressure differential between the outside and inside of the building created by strong winds acting on the wall, significant water ingress through hair-line cracks and other unintentional openings and the like readily occurs. In the absence of a cavity in the wall [as in barrier EIFS], such moisture will reach and damage the inside surface of the wall of the building. Accordingly, cavities are most preferred in walls, to prevent water ingress, provided the cavity is vented to atmosphere to allow for pressure equalization and accumulative water run-off out of the cavity. Thus, cladding systems relying solely on outer face sealing materials [barrier EIFS] suffer the risk of water ingress over time, enhanced by air pressure differentials, rain, and successive freezing and thawing of water contained within the cladding.

Thus, while the composite layered cladding of the prior art [non-drainable EIFS] provides a generally satisfactorily cladding which readily enables a decorative cladding system of a wall to be satisfactorily and quickly constructed, such a resultant wall often suffers from the effects of water damage under the air pressure differentials as aforesaid described, in the absence of an outside air-vented cavity.

It is an object of the present invention to provide an improved cladding for the wall of a building which can be readily constructed on-site and which provides air pressure equalization with the outside air.

The complete patent is avilable online at the U.S. Patent Office.