Cap sheet, roofing installation, and method

A cap sheet for cold-applied adhesive roof installations includes a reinforcement mat saturated with and encapsulated within SBS modified bitumen. Bitumen layers above and beneath the mat have top and bottom major surfaces. The top surface of the top bituminous layer has a first edge portion extending inward from and along a first lateral edge. The bottom surface of the bottom bituminous layer has a second edge portion extending inward from and along a second lateral edge. The bitumen in the edge portions is a pressure-sensitive adhesive that is covered by release liners for protection prior to installation. When the cap sheets are installed, the release liners are removed from the edge portions and overlapping edge portions of the cap sheets are pressed and adhesively bonded together to immediately form effective watertight, weather-secure seams.

BACKGROUND OF THE INVENTION

The subject invention relates to a cap sheet for cold-applied adhesive roof installations, and, more specifically, to a cap sheet with lateral edge portions that form an immediate and effective bond with the lateral edge portions of other like cap sheets when the cap sheet is used in a cold-applied adhesive roof installation to provide a watertight and weather-secure seam. The subject invention also relates to a cold-applied adhesive roof installation utilizing the cap sheet of the subject invention and the method of making a cold-applied adhesive roof installation incorporating the cap sheet of the subject invention.

There is currently a long-standing problem associated with the utilization of cap sheets in cold-applied adhesive roof installations. In such installations the cap sheets are currently bonded to an underlying layer, typically a layer of base felts, with a cold-applied adhesive coating. When the cap sheets are adhesively bonded to the underlying layer of the roof installation with a cold-applied adhesive coating, the cold-applied adhesive coating must also be applied to overlapping lateral edge portions of the cap sheets for the purpose of bonding these overlapping edge portions of the cap sheets together. In addition to the need for a full width application of the cold-applied adhesive to the cap sheet at the job site in order to bond the overlapping edge portions of the cap sheets together, current cold-applied adhesives used for such applications take a period of time to set up and form a watertight and weather-secure seam with some such cold-applied adhesives curing to their ultimate bond strength only after days or weeks. Accordingly, many applicators are uncomfortable with the practice of bonding the overlapping lateral edges portions of these cap sheets together with such cold-applied adhesives. With the time it takes for these cold-applied adhesives to develop their ultimate bond strength, if a lap joint formed by the lateral edge portions of the cap sheets is subjected to wind and/or precipitation, the lap joint formed by the lateral overlapping edge portions of the cap sheets can fail adhesively and allow leakage of water under the seams of such lap joints. Thus, there has remained a need for forming cap sheet lap joints where the overlapping lateral edge portions of the cap sheets forming the lap joints are more quickly bonded together to form a watertight and weather-secure seam.

SUMMARY OF THE INVENTION

The cap sheet of the subject invention for cold-applied adhesive roof installations solves the long-standing problems associated with the use of cap sheets in cold-applied adhesive roof installations by providing the cap sheets with lateral edge portions that can be overlapped and more quickly bonded together to form watertight and weather-secure seams. The cap sheet of the subject invention includes a mat that is saturated with and encapsulated within SBS modified bitumen. The SBS modified bitumen forms top and bottom bituminous layers on the top and bottom sides of the mat and the top and bottom surfaces of these bituminous layers form the top and bottom major surfaces of the cap sheet. The top major surface of the cap sheet has a first lateral edge portion extending inward from and along a first lateral edge of the cap sheet. The bottom major surface of the cap sheet has a second lateral edge portion extending inward from and along a second lateral edge of the cap sheet. The SBS modified bitumen in these lateral edge portions of the cap sheet is a pressure-sensitive adhesive which is covered by release liners to protect the pressure-sensitive adhesive from exposure during packaging, storage, shipment and handling. The release liners are peeled off at the job site immediately prior to the installation of the cap sheets. Other than its first lateral edge portion, the top major surface of the cap sheet is normally coated with an inorganic surfacing material such as roof granules. Other than its second lateral edge portion, the bottom major surface of the cap sheet is coated with a release material such as sand or some other inorganic surfacing material.

When the cap sheets of the subject invention are installed in a cold-applied adhesive roof installation, the cap sheets are adhered to base felts with a cold-applied adhesive. The release liners are peeled off the overlapping lateral edge portions of the cap sheets and the overlapping lateral edge portions of the cap sheets are pressed and immediately sealed together to form a watertight and weather-secure seal. Unlike current cold-applied adhesive roof installations, there is no need to wait for a cold-applied adhesive to cure to effectively bond the overlapping lateral edge portions of the cap sheets together and form a watertight and weather-secure seal. Furthermore, since the overlapping surfaces of the overlapping lateral edge portions of the cap sheets have a pressure-sensitive adhesive thereon, no adhesive is applied to these surfaces at the time of installation thereby reducing the amount of adhesive applied to the cap sheets in the field by about 10% when compared with current cold-applied adhesive installations.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown inFIGS. 1 to 3, the cap sheet20of the subject invention for cold-applied adhesive roof installations has a reinforcement mat22that is saturated with a SBS rubber modified bitumen. The SBS rubber modified bitumen encapsulates the reinforcement mat22and forms a top layer24over and coextensive with the reinforcement mat22and a bottom layer26beneath and coextensive with the reinforcement mat22. The top layer24of SBS rubber modified bitumen has a top major surface28and the bottom layer26of SBS rubber modified bitumen has a bottom major surface30. The cap sheet20has a first longitudinally extending lateral edge32(commonly referred to as the selvage edge) and a second longitudinally extending lateral edge34.

The top major surface28of the SBS rubber modified bitumen top layer24has a first lateral edge portion36extending inward from and along the first longitudinally extending lateral edge32of the cap sheet20. A layer of inorganic surfacing material38is adhered to and, except for the first lateral edge portion36of the cap sheet20, covers the top major surface28of the SBS rubber modified bitumen layer24. The first lateral edge portion36of the top major surface28of the SBS rubber modified bitumen layer24is free of the inorganic surfacing material38with the SBS rubber modified bitumen in the first lateral edge portion36of the cap sheet20functioning as a pressure-sensitive adhesive to bond the lateral edge portions of the cap sheets20together upon installation of the cap sheets20in a cold-applied adhesive roof installation to immediately form an effective watertight and weather-secure seam between the cap sheets. The SBS rubber modified bitumen in the first lateral edge portion36of the top major surface28is overlaid by a first release liner40.

The bottom major surface30of the SBS rubber modified bitumen bottom layer26has a second lateral edge portion42extending inward from and along the second longitudinally extending lateral edge34of the cap sheet20. A layer of release material44is adhered to and, except for the lateral edge portion42, covers the bottom major surface30of the SBS rubber modified bitumen layer26. The second lateral edge portion42of the bottom major surface30of the SBS rubber modified bitumen layer26is free of the release material44with the SBS rubber modified bitumen in the second lateral edge portion42of the cap sheet20functioning as a pressure-sensitive adhesive to bond the lateral edge portions of the cap sheets20together upon installation of the cap sheets20in a cold-applied adhesive roof installation to immediately form an effective watertight and weather-secure seam between the cap sheets. A second release liner46overlies the SBS rubber modified bitumen in the second lateral edge portion42of the cap sheet20. When the cap sheets20are installed in a cold-applied adhesive roof installation, the release liners40and46are peeled from the lateral edge portions36and42of the cap sheets20; the lateral edge portions36and42of successive cap sheets20are overlapped; and the overlapping lateral edge portions36and42of the successive cap sheets20are pressed and bonded together to immediately form an effective watertight and weather-secure seam between the cap sheets.

The reinforcement mat is a non-woven synthetic fiber mat such as a glass fiber or polyester mat, and preferably a 170 to 180-g/m2non-woven polyester mat such as that sold by Johns Manville International, Inc. under the trade designation Duragrid™ 055/170 polyester mat.

Preferably, the SBS (Styrene-Butadiene-Styrene) rubber modified bitumen has the following composition:

Preferably, the inorganic surfacing materials forming the layer of inorganic surfacing materials38on the top major surface26of the cap sheet20are roofing granules, e.g. ceramic-coated granite. Preferably, the release materials forming the release layer44on the bottom major surface30of the cap sheet20are inorganic surfacing materials such as sand. The release liners40and46may be strips of a sheet or film material that have their surfaces that are in contact with the SBS rubber modified bitumen in the edge portions36and42of the cap sheet coated with a conventional release agent. For example, the release liners can be strips of polymeric film coated with a silicon release agent.

The cap sheet20is typically between about36and about 40 inches in width, preferably about 40 inches in width, and is typically sold in 1 square (108 square foot) rolls. The lateral edge portions36and42of the cap sheets20are typically between about2and about 4 inches in width, preferably about 4 inches in width, and when installed, successive cap sheets20are normally overlapped the full width of the lateral edge portions.

As shown inFIG. 4, a typical cold-applied adhesive roof installation incorporating the cap sheets20may include roof insulation boards50, such as but not limited to high density, low thermal, rigid insulation boards composed primarily of expanded perlite with reinforcing cellulosic fibers and selected binders. An example of such an insulation board is an insulation board sold by Johns Manville International, Inc. under the trade designation DuraBoard™ insulation board. The insulation boards50are secured to the roof deck52and a layer of light weight, asphalt coated, base felts54, e.g. fiber glass base felts, overlie and are secured by a cold-applied modified asphalt, roof ply adhesive to the insulation boards. An example of such a base felt is a base felt sold by Johns Manville International, Inc. under the trade designation PermaPly® 28 base felt. The cap sheets20overlie and are adhesively secured to the layer of base felts by a cold-applied modified asphalt, roof ply adhesive layer56. An example of a such a cold applied modified asphalt, roof ply adhesive is an adhesive sold by Johns Manville International, Inc. under the trade designation MBR® quick set adhesive. When the cap sheets20are applied over the layer of base felts54, the overlapping lateral edge portions36and42of the cap sheets20are pressed and bonded together to form an effective watertight, weather-secure seam. There is no need to wait for a cold-applied adhesive on the lateral edge portions of cap sheets to develop its ultimate bond strength and seal the overlapping edge portions of the cap sheets as in previous traditional cold-applied adhesive installations.

In describing the invention, certain embodiments have been used to illustrate the invention and the practices thereof. However, the invention is not limited to these specific embodiments as other embodiments and modifications within the spirit of the invention will readily occur to those skilled in the art on reading this specification. Thus, the invention is not intended to be limited to the specific embodiments disclosed, but is to be limited only by the claims appended hereto.