Roofing Underlayment

Abstract

The present invention provides a composite sheet material ( 10 ) that is particularly useful as an underlayment material in roofing applications. In particular, the present invention provides a composite sheet material ( 10 ) that is flexible, relatively lightweight, resistant to water as well as being water vapor permeable and resistant to tearing. In addition, the composite sheet material ( 10 ) includes an outer non-skid surface ( 18 ) that can help prevent slippage of workers during installation of the roofing system. Embodiments of the composite sheet material can help provide a roofing\structure, such as a shingled roof, with fire resistance so that the roof can meet the Fire Resistance requirements of ASTM E 108 - 07 a, Class A.

1 . A method of installing a roof system on a building comprising
 covering an exterior surface of a roof structure with a breathable, composite sheet material having water barrier and fire resistant properties, the composite sheet material including a woven or nonwoven substrate defining an upper surface of the sheet material, and an extrusion coated film layer covering an opposite surface of the nonwoven substrate and defining a lower surface of the sheet material, wherein the film layer has a moisture vapor transmission rate of at least 35 g/m 2 /24 hr. at 50% relative humidity and 23° C., and a hydrostatic heads of at least 55 cm; and   positioning the composite sheet material onto the roof structure so that that the film layer faces towards the roof structure and the nonwoven substrate faces outwardly to provide a non-skid surface.   
     
     
         2 . The method of  claim 1 , wherein the film layer comprises a polyolefin polymer and at least 40% by weight inorganic filler. 
     
     
         3 . The method of  claim 1 , wherein said film layer comprises at least 40% by weight inorganic filler, and sheet material has been subjected to stretching in both the CD and the MD by incremental stretching to impart to the composite fabric a moisture vapor transmission rate (MVTR) of at least 100 g/m 2 /24 hr. at 50% relative humidity and 23° C. 
     
     
         4 . The method of  claim 1 , wherein the film layer has a basis weight that is from about 70 to 100 g/m 2 . 
     
     
         5 . The method of  claim 1 , wherein the film layer has a basis weight that is at least about 80 g/m 2 . 
     
     
         6 . The method of  claim 1 , wherein the non-skid surface of the composite sheet material has a coefficient of friction that is at least 0.70. 
     
     
         7 . The method of  claim 1 , wherein the non-skid surface of the composite sheet material has a coefficient of friction that is from about 0.73 to 0.88. 
     
     
         8 . The method of  claim 1 , wherein the film layer is a monolithic film comprising a blend of polypropylene and from about 20 to 30% by weight of a co-polyether amide, a block co-polyether ester, or a combination thereof. 
     
     
         9 . The method of  claim 1 , further comprising the step of attaching a plurality of shingles to the composite sheet material. 
     
     
         10 . The method of  claim 9 , wherein the roof system comprising the composite sheet material meets the requirements of ASTM E 108 Class A Fire Resistant Test. 
     
     
         11 . The method of  claim 1 , wherein the nonwoven substrate is a spunbond nonwoven fabric comprising polypropylene continuous filaments. 
     
     
         12 . A composite sheet material useful as a waterproof underlayment for a roof of a structure, the sheet material comprising a woven or nonwoven substrate and a film layer covering a surface of the nonwoven substrate, the film layer comprising a polyolefin polymer and at least 40% by weight inorganic filler, and wherein the composite sheet material has a moisture vapor transmission rate (MVTR) of at least 34 g/m 2 /24 hr. at 50% relative humidity and 23° C., and a hydrostatic heads of at least 55 cm, and wherein the film layer has a basis weight of at least 80 g/m 2 . 
     
     
         13 . The sheet material of  claim 12 , wherein the s sheet material has been subjected to stretching in both the CD and the MD. 
     
     
         14 . The sheet material of  claim 13 , wherein the film layer is extrusion coated onto the substrate and wherein composite sheet material has been incrementally stretched to render the composite sheet material breathable. 
     
     
         15 . The sheet material of  claim 12 , wherein a roof system comprising a roof deck, a plurality of covering shingles and the composite sheet material as an underlayment material disposed between the roof deck and shingles meets the requirements of ASTM E 108 Class A Fire Resistant Test. 
     
     
         16 . The sheet material of  claim 12 , wherein the substrate includes an exposed non-skid surface having a coefficient of friction that is from 0.70 to about 0.90. 
     
     
         17 . The sheet material of  claim 12 , wherein the substrate includes an exposed non-skid surface having a coefficient of friction that is from about 0.73 to 0.88. 
     
     
         18 . The sheet material of  claim 12 , wherein the film layer includes a UV stabilizer, a thermal stabilizer, or a combination thereof. 
     
     
         19 . A roofing system comprising: a) a roof deck of a building; b) an underlayment material attached to said roof deck, wherein the underlayment material comprises a composite sheet material having water barrier and fire resistant properties, the composite sheet material including a nonwoven substrate defining an upper surface of the sheet material, and an extrusion coated film layer covering an opposite surface of the nonwoven substrate and defining a lower surface of the sheet material that faces towards the roof deck, wherein the film layer has a moisture vapor transmission rate of at least 35 g/m 2 /24 hr. at 50% relative humidity and 23° C., and a hydrostatic heads of at least 55 cm; and c) a multiplicity of courses of roofing shingles attached to said underlayment material, and wherein the roof system meets the requirements of ASTM E 108 Class A Fire Resistant Test. 
     
     
         20 . The roofing system of  claim 19 , wherein said film layer comprises at least 40% by weight inorganic filler, and sheet material has been subjected to stretching in both the CD and the MD by incremental stretching to impart to the composite fabric a moisture vapor transmission rate (MVTR) of at least 100 g/m 2 /24 hr. at 50% relative humidity and 23° C. and a hydrostatic head of at least 55 cm. 
     
     
         21 . The roofing system of  claim 19 , wherein the film layer has a basis weight that is from about 70 to 100 g/m 2 . 
     
     
         22 . The roofing system of  claim 19 , wherein the film layer has a basis weight that is at least about 80 g/m 2 . 
     
     
         23 . The roofing system of  claim 19 , wherein the non-skid surface of the composite sheet material has a coefficient of friction that is at least 0.70. 
     
     
         24 . The roofing system of  claim 19 , wherein the non-skid surface of the composite sheet material has a coefficient of friction that is from about 0.73 to 0.88. 
     
     
         25 . The roofing system of  claim 19 , wherein the film layer is a monolithic film comprising a blend of polypropylene and from about 20 to 30% by weight of a co-polyether amide, a block co-polyether ester, or a combination thereof. 
     
     
         26 . A roofing system comprising: a) a roof deck of a building; b) an underlayment material attached to said roof deck, wherein the underlayment material comprises a composite sheet material having water barrier and fire resistant properties, the composite sheet material including a woven or nonwoven substrate and a film layer covering a surface of the substrate, the film having a basis weight of at least 70 g/m 2  and a moisture vapor transmission rate of at least 35 g/m 2 /24 hr. at 50% relative humidity and 23° C., and a hydrostatic heads of at least 55 cm; and c) a multiplicity of courses of roofing shingles attached to said underlayment material, and wherein the roof system meets the requirements of ASTM E 108 Class A Fire Resistant Test. 
     
     
         27 . The roofing system of  claim 26 , wherein the substrate layer faces in the direction of the roof deck. 
     
     
         28 . The roofing system of  claim 26 , wherein the film layer faces in the direction of the roof deck. 
     
     
         29 . The roofing system of  claim 26 , wherein the substrate layer comprises a woven slit film.