Stock material or miscellaneous articles – Composite – Of bituminous or tarry residue
Reexamination Certificate
2000-09-15
2002-12-31
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Composite
Of bituminous or tarry residue
C428S357000, C428S323000, C428S105000, C428S317700, C052S309130, C052S309150, C052S506010
Reexamination Certificate
active
06500560
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an asphalt coated structural article. The structural article, which comprises a substrate having an ionic charge is coated on one side with a non-asphaltic coating having essentially the same ionic charge and is coated on the other side with a layer of asphaltic material. The asphalt coated structural article may be used as a waterproofing barrier and specifically as a roofing underlayment for concrete tiles. The asphalt coated structural article may also be useful in other roof assemblies. The present invention provides a temporary roof cover that achieves a class C rating for protection against moderate to severe exposure to fire. When used as a roofing underlayment for concrete tiles, the present invention achieves 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 water resistance and fire 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 wrinkles, undulations, and distortions. It may also distort under high moisture conditions. Saturated organic felt underlayment has poor fire resistance and when burned, disintegrates.
Traditional underlayments are vulnerable to damage before the protective roofing material is layed down. For example, traditional underlayments can be damaged by workers walking on the underlayment or by items dropped on the underlayment. Ripped or torn underlayment will not serve as an effective waterproofing barrier and must be patched before the roofing material can be layed down.
In addition, conventional asphalt underlayments can stain certain roofing materials, such as concrete tiles or shingles. The asphalt from the underlayment migrates upward from the underlayment and into the concrete tile, thereby staining the tile.
The roofing underlayment should also help 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 non-combustible 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.
There is a need for a sturdy, water-resistant and fire-resistant roofing underlayment system that does not tend to wrinkle or distort when layed down and that is resistant to tearing or ripping. There is also a need for a roofing underlayment that does not tend to stain concrete tiles.
Other parts of a building structure besides the roof often require a waterproofing barrier. For example, subterranean concrete walls often require a waterproofing barrier to prevent water seepage into the basement. Concrete walls are traditionally waterproofed by spraying or coating the walls with a waterproof substance or by attaching a waterproof fabric to the wall. However, these waterproofing barriers must be protected from damage, particularly required when the waterproofing barrier is applied to the outside of a subterranean wall. For example, a waterproofing barrier applied to the outside of a subterranean wall can be damaged by rocks or other materials in the dirt that adjoins the outside wall.
One conventional method of protecting the waterproofing barrier from damage involves overlaying a protecting board, such as a foam board, over the waterproof barrier. This added step of adding a protecting layer increases the time and expense of waterproofing. Thus, there has long been a need for an article that can be used as a waterproofing barrier without the need to apply an additional protecting layer.
SUMMARY OF THE INVENTION
The present invention involves an asphalt coated structural article which comprises a substrate having an ionic charge that is coated on one side with a non-asphaltic coating having essentially the same ionic charge as the substrate and that is coated on the other side with an asphaltic material.
The present invention may be utilized as a waterproofing barrier that does not require the application of an additional layer to protect the waterproof barrier from damage.
Specifically, the present invention is useful in roof assemblies. The asphalt coated structural article provides a temporary roof cover that achieves a class C rating for protection against moderate to severe exposure to fire. The asphalt coated structural article, when used as a roofing underlayment for concrete tiles results in a class B or better (Class A) rating for protection for the roofing materials against moderate to severe exposure to fire, without the use of intermediate barriers such as gypsum or other non-combustible decking.
In addition, 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 gypsum or non-combustible decking. The present invention provides a durable roof covering that is resistant to ripping or tearing. The present invention tends not to wrinkle, undulate or distort when applied to roofing or walls as compared to traditional felt underlayments. The present invention may be used with a variety of roof assemblies but most particularly as an underlayment for thin concrete roofing tiles, enabling the roof to achieve a class A fire rating.
DETAILED DESCRIPTION
The applicants have invented an asphalt coated structural article which comprises a substrate having an ionic charge that is coated on one side with a coating having essentially the same ionic charge as the substrate and that is coated on the other side with an asphaltic material.
The asphalt covering may be any type of asphaltic material that can act as a water barrier. Examples of asphalt that can be used include oxidized, unoxidized, rubberized, filled and unfilled, virtually any asphaltic compound which can be coated, mopped or sprayed. In a preferred embodiment, the asphalt may also serve as an adhesive. One example of an adhesive asphalt is peel-and-stick asphalt, also known as ice and snow shield, which is sold by numerous manufacturers including Koppers Industries, GAF Materials Corp., and G. S. Roofing. Peel-and-stick asphalt is traditionally a styrene-butadiene-styrene (“S
Bryson Michael L.
Kiik Matti
Tobin Robert Joseph
Baker & Botts LLP
Bernatz Kevin M.
Elk Corporation of Dallas
Thibodeau Paul
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