Cap sheet, roofing installation, and method — Johns Manville

Cap sheet, roofing installation, and method - Johns Manville

FIG. 1 is a partial schematic perspective view of the top major surface of a cap sheet of the subject invention.

FIG. 2 is a partial schematic perspective view of the bottom major surface of the cap sheet of FIG. 1.

FIG. 3 is a transverse schematic cross section through the cap sheet of FIG. 1, taken substantially along lines 33 of FIG. 1, in a larger scale than FIG. 1, and with a midportion of the cap sheet broken away.

FIG. 4 is a partial schematic view from above of a typical cold-applied adhesive roof installation incorporating the cap sheet of the subject invention with pieces of a roof insulation board layer removed to show part of the roof deck, portions of a base felt layer peeled back to show part of the roof insulation board layer, and portions of the cap sheet layer peeled back to show part of the base felt layer.

As shown in FIGS. 1 to 3, the cap sheet 20 of the subject invention for cold-applied adhesive roof installations has a reinforcement mat 22 that is saturated with a SBS rubber modified bitumen. The SBS rubber modified bitumen encapsulates the reinforcement mat 22 and forms a top layer 24 over and coextensive with the reinforcement mat 22 and a bottom layer 26 beneath and coextensive with the reinforcement mat 22. The top layer 24 of SBS rubber modified bitumen has a top major surface 28 and the bottom layer 26 of SBS rubber modified bitumen has a bottom major surface 30. The cap sheet 20 has a first longitudinally extending lateral edge 32 (commonly referred to as the selvage edge) and a second longitudinally extending lateral edge 34 .

The top major surface 28 of the SBS rubber modified bitumen top layer 24 has a first lateral edge portion 36 extending inward from and along the first longitudinally extending lateral edge 32 of the cap sheet 20. A layer of inorganic surfacing material 38 is adhered to and, except for the first lateral edge portion 36 of the cap sheet 20. covers the top major surface 28 of the SBS rubber modified bitumen layer 24. The first lateral edge portion 36 of the top major surface 28 of the SBS rubber modified bitumen layer 24 is free of the inorganic surfacing material 38 with the SBS rubber modified bitumen in the first lateral edge portion 36 of the cap sheet 20 functioning as a pressure-sensitive adhesive to bond the lateral edge portions of the cap sheets 20 together upon installation of the cap sheets 20 in 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 portion 36 of the top major surface 28 is overlaid by a first release liner 40 .

The bottom major surface 30 of the SBS rubber modified bitumen bottom layer 26 has a second lateral edge portion 42 extending inward from and along the second longitudinally extending lateral edge 34 of the cap sheet 20. A layer of release material 44 is adhered to and, except for the lateral edge portion 42. covers the bottom major surface 30 of the SBS rubber modified bitumen layer 26. The second lateral edge portion 42 of the bottom major surface 30 of the SBS rubber modified bitumen layer 26 is free of the release material 44 with the SBS rubber modified bitumen in the second lateral edge portion 42 of the cap sheet 20 functioning as a pressure-sensitive adhesive to bond the lateral edge portions of the cap sheets 20 together upon installation of the cap sheets 20 in a cold-applied adhesive roof installation to immediately form an effective watertight and weather-secure seam between the cap sheets. A second release liner 46 overlies the SBS rubber modified bitumen in the second lateral edge portion 42 of the cap sheet 20. When the cap sheets 20 are installed in a cold-applied adhesive roof installation, the release liners 40 and 46 are peeled from the lateral edge portions 36 and 42 of the cap sheets 20 ; the lateral edge portions 36 and 42 of successive cap sheets 20 are overlapped; and the overlapping lateral edge portions 36 and 42 of the successive cap sheets 20 are 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/m 2 non-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:


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