BREATHABLE COMPOSITE MOISTURE BARRIER ROOFING UNDERLAYMENT

Abstract

A multi-layer laminated roofing underlayment comprising a sheet of asphalt impregnated felt paper bonded to a sheet of porous non-woven polymer fabric in which the bonding adhesive is hot-melt modified asphalt, spot coated onto the felt paper in order to maintain water vapor permeability.

Claims

1. A multi-layer laminated roofing underlayment comprising a sheet of asphalt impregnated felt paper bonded to a sheet of porous non-woven polymer fabric in which the bonding adhesive is hot-melt modified asphalt, spot coated onto the felt paper in order to maintain water vapour permeability.

2. A multi-layer laminated roofing underlayment according to claim 1, where an open grid fiberglass scrim is incorporated within the lamination.

3. A multi-layer laminated roofing underlayment according to claim 2, where one face of the said porous non-woven polymer fabric has an anti-skid surface of 1 mm high raised polymer dots spaced about 6 mm apart in all directions.

4. A multi-layer laminated roofing underlayment according to claim 3, where the hot-melt adhesive spot coating procedure leaves sufficient uncoated voids resulting in a minimum water-vapor permeance of 5 Perms in the described lamination.

5. A multi-layer laminated roofing underlayment according to claim 1 where the porous non-woven polymer fabric has a basis weight ranging between 50 gsm (grams per square meter) to 250 gsm, with a preferred basis weight of 100 gsm.

6. A multi-layer laminated roofing underlayment according to claim 1, where the asphalt impregnated felt paper has a basis weight ranging between 90 gsm to 1350 gsm with a preferred basis weight of about 500 gsm.

7. A multi-layer laminated roofing underlayment according to claim 1 where a second sheet of porous non-woven fabric is bonded to the second face of the asphalt impregnated felt paper using a thinly spread fast-setting adhesive such as Chloroprene applied in a manner which maintains the water vapour permeability of the laminated sheet.

8. Providing a thin gap for drainage and air flow beneath a roofing material with the embodiment of raised dots on the surface of an underlayment sheet.

9. A hot melt adhesive according to claim 1 wherein the bonding asphalt has a penetration rating between 80 to 100 mm and the modifying polymer is a a styrene-butadiene-stryrene, SBS, polymer combined with a styrene-isoprene-styrene, SIS, polymer designed to produce an elastomeric compound having high strength bonding properties.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 shows the components making up the preferred embodiment of the present invention. The asphalt felt layer 100 has spot-coated asphalt 101 on one face, to which is bonded a layer of open scrim 102 and a layer of non-woven synthetic fabric 103, having a surface of raised polymer dots 104.

[0009] FIG. 2 shows a second embodiment of the present invention in which a second layer of non-woven synthetic fabric 105 is bonded to the second face of the asphalt felt layer 100, utilizing a second adhesive 106.

DETAILED DESCRIPTION

[0010] Accordingly the main embodiments of the present invention are described as:

[0011] An improved composite sheet made of asphalt impregnated felt paper which is spot-coated with closely spaced spots of a hot-melt adhesive on one face to which a ply of non-woven synthetic fabric is pressed and bonded to this face in a continuous process on a machine designed for laminating materials.

[0012] The resulting composite lamination results in a sheet which has the strength and stability of the non-woven synthetic fabric while retaining the water resistance and permeability of the asphalt felt. A fiberglass scrim may also be sandwiched within the described lamination to add further strength.

[0013] And a second ply of non-woven fabric may be bonded to the second face of the asphalt felt sheet to further enhance its strength.

[0014] A further unique innovation of the present invention is to utilize a non-woven synthetic fabric having an anti-skid surface on one of its faces in order to provide enhanced foot traction for workers on sloped roofs. The anti-skid surface may consist of a grid of evenly spaced raised polymer dots on one surface of the non-woven sheet, which dots are about 2 mm wide by 1 mm in height and spaced about 6 mm apart.

[0015] The raised dots of the present invention can also serve to create a thin air gap beneath any roofing material such that the gap can help drain errant moisture and also permit some wind driven air movement to occur beneath roofing layers to assist in moisture removal.

[0016] A further innovation of the present invention is to use polymer modified asphalt in hot molten form for the laminating adhesive which is applied in a closely spaced spot-coated manner to maintain windows of permeability. This unique method of bonding results in a very rapidly setting bond which permits high speed production and still maintains the water vapor permeability of the laminated sheet.

[0017] Other common adhesives may also be used and applied in a spot coated manner in order to maintain permeability. Chloroprene is an example of one such adhesive.

[0018] While these are the preferred embodiments of the present invention, various other materials or arrangements of components can be utilized by those skilled in the art to achieve a finished material possessing the described characteristics of the present invention. Some but not all examples of variations are: [0019] a. Asphalt saturated Kraft paper may be used instead of roofing felt. [0020] b. A woven polymer sheet may be used in place of the non-woven fabrics. [0021] c. A non-woven fabric sheet without the anti-skid polymer dots may be used. [0022] d. The non-woven or woven polymer sheets may be comprised of other polymers such as polyethylene, polypropylene, polyester and similar materials.