Static structures (e.g. – buildings) – Wall – ceiling – floor – or roof designed for ventilation or... – With the vent or drain entirely along at least one...
Reexamination Certificate
1999-02-24
2001-05-22
Friedman, Carl D. (Department: 1772)
Static structures (e.g., buildings)
Wall, ceiling, floor, or roof designed for ventilation or...
With the vent or drain entirely along at least one...
C052S660000, C052S663000, C052S302600, C052S302100, C052S664000
Reexamination Certificate
active
06233890
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to improvements in exterior finishing systems such as, for example, exterior insulation and finish systems (EIFS) and direct-applied exterior finish systems (DEFS) for buildings. Such EIFS systems are fully described in U.S. Pat. No. 4,647,496. More particularly, this invention relates to an improvement in the management of water as a line of defense by harmlessly handling any unwanted water that has penetrated behind the exterior cladding.
Originally, EIFS was an exterior wall concept designed to have high insulation values and a reliable stucco finish that could be economically created in a wide array of textures and colors. It immediately became successful because it provided so much performance for so little cost. The most unusual aspect of the system was that expanded polystyrene (EPS) insulation was installed on the exterior side of the wall by adhesively bonding it to a substrate, forming a base for an exterior coating as well as adding more insulation to the building. The surface typically has a ⅛-inch-thick synthetic-stucco finish system which performs two functions. It is designed to (1) provide a face-seal or barrier to seal out moisture and (2) provide a decorative finish at the same time. This ⅛-inch-thick finish system consists of reinforcing mesh, latex-fortified basecoat, and an aggregated, polymeric, textured finish.
The principal weaknesses in the prior art EIFS is that they have only one line of defense against water intrusion and no means to drain intruding water. Although the surface usually forms an effective water barrier, intersections of the surface with other elements, such as window frames, door frames, etc., often leave gaps or openings that driving rain can penetrate. Once inside the sealed wall and behind the cladding, the water can remain trapped long enough before evaporating to damage or rot any water-sensitive elements, to which the insulation is bonded including, oriented-strand board, plywood, or gypsum sheathing.
Whether the prior art exterior wall systems provide an insulation layer attached to the exterior cladding which is coated with a stucco-look finish (EIFS), or the stucco-look finish is applied directly over the cladding (DEFS), there has been no provision for water managed relief at the back side of the cladding.
As a result of these problems, a need has arisen for water-managed exterior finishing systems. The present invention discloses an exterior wall system that includes a drainage medium on the outer surface of a weather-resistive membrane. This system provides the designer and building owner with a combination of the optimal properties of a weather-resistive membrane with the long-term reliability of water management.
SUMMARY OF THE INVENTION
The disclosed drainable weather-resistive membrane, when incorporated into a typical exterior finishing system, efficiently manages the drainage of penetrating water by directing the water to weeps or the like. Should water flank the exterior cladding, or enter openings for penetrations, it will be stopped at the weather-resistive membrane, then drained to flashing elements, and removed to the outside through the weeps, thereby protecting the stud cavity and any water sensitive materials in the wall cavity from damage.
In a preferred embodiment, the system utilizes a typical sheathing membrane, as known to one of ordinary skill in the art, that combines both weather resistance with a provision for water drainage. The exterior side of the sheathing membrane is embossed with a drainage medium to form a water managed plane that allows any water that penetrates through the exterior cladding to collect along a textured pattern and drain down the interstitial spaces created by the pattern. In a more preferred embodiment, the drainage medium is a mesh pattern with nodes at the regular intersections of the mesh. When an exterior cladding is applied over the mesh pattern, a drainage space is created between the inner face of the cladding substrate and the sheathing membrane, providing a flow path for the water to drain downwards.
Unlike prior art weather-resistive membranes that include a means for managing water, the disclosed invention provides the weather-resistive membrane with a water vapor permeance in the range of three to forty perms and a water penetration resistance capable of maintaining a minimum hydrostatic head of four inches for a seventy-two hour period. An exterior finishing system that includes this invention can be installed over wood- or steel-stud framing. A structural sheathing may also be included, depending on the design criteria. Flashing components are installed along the bottom edge the system to collect the drained water and direct it away from the system.
REFERENCES:
patent: 3884009 (1975-05-01), Frohlich et al.
patent: 4730953 (1988-03-01), Tarko
patent: 5826388 (1998-10-01), Irving
USG Corp. publicationExterior Systemsthree page article titled “Taking the Doubt out of EIFS Wall Performance” by Ted Kellam, 1997.
Fortifiber Corp. eight page brochure and four pages of specifications for moisture vapor barriers; sample specimens of Fortifiber Super Jumbo Tex® barrier and Moistop® flashing, 1998.
Specimen of Tyvek® barrier jointly developed by USG Corp. and Dupont Corp., 1998.
Dorsey Dennis L.
Friedman Carl D.
Janci David
Lee Mann Smith McWilliams Sweeney & Ohlson
Lorenzen John M.
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