An underlayment material has a fiber mat partially infused and/or coated with asphalt and coated with silicone coating. A selvedge edge, may be coated or uncoated. The back of the underlayment has a self-adhesive coating, which is protected before use by a siliconized release film. The upper surface of the underlayment is coated with silicone composition providing waterproofing and radiation control. When unsaturated, the selvedge edge of fibrous material establishes a reinforced bond with an overlying sheet. When saturated with asphalt, the bond at the selvedge edge between adjacent sheets is between the asphalt layer of the selvedge edge and the adhesive on the bottom of the adjacent sheet.