Self-adhering underlayment sheets to form waterproofing joints, related building assemblies and methods

A building underlayment sheet comprising:

• an underlayment lamina having a top surface and a bottom surface, wherein the bottom surface includes an interior portion and a selvage portion that extends from the interior portion of the bottom surface to a terminal distal edge of the sheet, wherein each of the interior portion of the bottom surface and the selvage portion of the bottom surface bears a self adhesive layer, and the selvage portion of the bottom surface bears a bonding composition that is laid over the self adhesive layer and which is capable of bonding to a top surface of a second underlayment lamina to form a full lap joint.

A building underlayment sheet comprising:

• an underlayment lamina having a top surface and a bottom surface, wherein the bottom surface includes an interior portion and a selvage portion that extends from the interior portion of the bottom surface to a terminal distal edge of the sheet, wherein each of the interior portion of the bottom surface and the selvage portion of the bottom surface bears a first self adhesive layer, the top surfaces bears a second self adhesive layer;
• and the selvage portion of the bottom surface bears a bonding composition that is laid over the self adhesive layer and which is capable of bonding to a top surface of a second underlayment lamina to form a full lap joint.

A building underlayment sheet comprising:

• an underlayment lamina having a top surface and a bottom surface, wherein the bottom surface includes an interior portion and a selvage portion that extends from the interior portion of the bottom surface to a terminal distal edge of the sheet, wherein the interior portion of the bottom surface bears a self adhesive layer comprising an asphalt, poly(styrene-butadiene-styrene)(SBS), and a tackifier, and the selvage portion of the bottom surface bears a bonding composition comprising asphalt, poly(styrene-butadiene-styrene), ground tire rubber (GTR), and tackifier.