Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Felt fabric
Reexamination Certificate
2000-09-15
2003-07-01
Cole, Elizabeth M. (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Felt fabric
C442S064000, C442S065000, C442S068000, C442S136000, C442S172000, C428S141000, C428S489000, C428S357000, C428S323000, C428S105000, C428S317700
Reexamination Certificate
active
06586353
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a roofing underlayment system useful in roof assemblies comprising at least two layers of a coated structural article which comprises a substrate having an ionic charge coated with a coating having essentially the same ionic charge, or at least one layer of such coated structural article in combination with at least one layer of felt material. The underlayment of the present invention allows roof assemblies to achieve a class B or better (Class A) rating for protection against moderate to severe exposure to fire.
BACKGROUND OF THE INVENTION
Roofing underlayment is applied to the deck of a roof before the application of roofing shingles or other roofing material primarily to shield the roof deck from moisture, both during assembly and after roof installation. Underlayment also helps reduce “picture framing” in which the outline of deck panels caused by irregularities in the deck surface may be visible through the roofing material applied to the roof deck. Further, the roofing underlayment should be a key component of a fire rated roof assembly. The underlayment structure should assist in preventing flaming of the underside of the deck when exposed to fire on top of the roof covering assembly. Thus, the benefits of the underlayment in the roof assembly are to provide additional fire resistance and water resistance, and to provide uniformity of the appearance of the roof surface.
Conventional roofing underlayment typically comprises a dry cellulosic felt that can be impregnated or saturated with an organic material such as asphalt. When used as an underlayment, felt typically does not provide a completely flat surface, but has undulations and distortions. It may also distort under high moisture conditions. Saturated organic felt underlayment has poor fire resistance and when burned, disintegrates.
There has long been a need for roofing underlayment that will protect a roof deck from flaming, even when noncombustible roofing materials are employed as the visible roof covering. For instance, metal roofing materials, either standing seam or shingles, are typically considered noncombustible materials. However, for noncombustible metal roof coverings to achieve a Class A fire resistance rating, a ½ inch layer of gypsum board or a layer of ¼ inch Dens-Deck board is usually required on top of the roof deck beneath the saturated felt underlayment that is under the metal roof covering. That is because the heat of a fire burning on top of roofing materials, including noncombustible metal roof coverings, passes through the material to the underlayment which is then susceptible to burning and disintegration. Thus, it has heretofore been deemed necessary to place gypsum board or Dens-Deck board on a roof deck beneath felt underlayment and noncombustible metal roofing materials, even though such boards raise the cost of the roofing materials and their application, and despite the facts that they are heavy, difficult to handle, require covering to protect from rain, and are slippery on steep slopes; because otherwise, a Class A fire resistance rating cannot be achieved.
Thus, there is a need for a roofing underlayment system which provides fire resistance (preferably Class B or better), water resistance, and uniformity of the appearance of the roof surface, but which is not heavy, difficult to handle, slippery nor overly costly.
SUMMARY OF THE INVENTION
The present invention provides an improved roofing underlayment system comprising at least two layers of a coated structural article which comprises a substrate having an ionic charge coated with a coating having essentially the same ionic charge, or at least one layer of such coated structural article in combination with at least one layer of felt material. The felt material may be comprised of cellulosic fibers, glass fibers or mixtures thereof. In addition, the felt material may be saturated with an organic material, such as asphalt. The coating of the coated structural article consists essentially of a filler material and a binder material wherein the binder material bonds the filler material together and to the substrate and wherein the coating does not bleed through the substrate.
The roofing underlayment system of the present invention allows roof assemblies to achieve a Class B or better (Class A) rating for protection against moderate to severe exposure to fire without the use of intermediate barriers such as gypsum or other noncombustible decking. In addition, the roofing underlayment system of the present invention is not difficult to handle since it is lighter in weight than other roofing underlayment systems, is not slippery on steep slopes and is not as costly as other roofing underlayment systems comprising intermediate barriers.
The roofing underlayment system of the present invention may be used with a variety of roof assemblies including, but not limited to, combustible products and noncombustible products that do not meet a Class B or better fire resistance rating. Nonlimiting examples of such roof assemblies include, Class C asphalt shingles, plastic molded or extruded shingles, non-asphalt composite shingles, rubber based shingles, steel shingles, steel standing seam roofing systems, steel corrugated panel roofing systems, aluminum standing steam roofing systems, aluminum shingles, clay tiles, light weight concrete roofing shingles and cement tiles.
DETAILED DESCRIPTION
The applicants have discovered that an improved roofing underlayment system can be made by combining at least two layers of a coated structural article which comprises a substrate having an ionic charge coated with a coating having essentially the same ionic charge, or at least one layer of such coated structural article with at least one layer of a felt material.
Examples of suitable felt material include cellulosic fibers, glass fibers and mixtures thereof. The felt material may be saturated with an organic material, such as asphalt. Examples of such materials are disclosed in U.S. Pat. Nos. 4,513,045, and 5,717,012. The texts of both of these patents are incorporated herein by reference.
The coating of the structural article consists essentially of a filler material and a binder material. For example, U.S. Pat. No. 5,965,257, the text of which is incorporated herein by reference, teaches that by coating the substrate with a coating having essentially the same ionic charge, a zero bleed through product is made while using only two major ingredients in the coating. By producing a coating having essentially the same ionic charge as the substrate, a zero bleed through product may be produced having a low binder content and no viscosity modifiers.
The substrate of the structural article may be any suitable reinforcement material capable of withstanding high temperatures such as glass fibers, polyester fibers, cellulosic fibers, asbestos, steel fibers, alumina fibers, ceramic fibers, nylon fibers, graphite fibers, wool fibers, boron fibers, carbon fibers, jute fibers, polyolefin fibers, polystyrene fibers, acrylic fibers, phenol-formaldehyde resin fibers, aromatic and aliphatic polyamide fibers, polyacrylamide fibers, or mixtures thereof which may include bi-component fibers or multi-component fibers.
In a preferred embodiment, the filler employed in the coating of the structural article may be class F fly ash, class C fly ash or mixtures thereof. Preferably, the filler is class F fly ash wherein 90% to 95% by weight of the fly ash is aluminosilicate. Such a fly ash, known as Alsil O4TR, is produced by JTM Industries, of Kennesaw, Ga. In an alternative embodiment, the filler may be charged calcium carbonate or ceramic microspheres, or a blend of fly ash and calcium carbonate, or a blend of fly ash, calcium carbonate and ceramic microspheres.
The table below provides, in percentages, some of the combinations of calcium carbonate, fly ash and ceramic microspheres which may be utilized as the filler component in the coating:
TABLE I
A
B
C
D
E
F
%
%
%
%
%
%
1. Water
18.9
25.9
37.33
25.9
24.9
24.9
2. Acr
Ahluwalia Younger
Bryson Michael L.
Kiik Matti
Tobin Robert Joseph
Baker & Botts L.L.P.
Cole Elizabeth M.
Elk Corp. of Dallas
Torres Norca L.
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