R703.2

Section R703.2 is titled 'Water-resistive barrier' and covers the requirements for a water-resistive barrier on exterior walls. The requirement for a prescriptive water-resistive barrier material conforming to a standard or other approved water-resistive barriers installed in a particular layer of the exterior wall assembly, minimum overlapping dimensions of barrier layers, completeness of installation, and intersection requirements at penetrations and appendages to maintain a water-resistant building envelope in accordance with a cross-reference to another section of this code is established. The purpose of this section is to prevent premature degradation from water intrusion through exterior walls into a building.

The model shows a section of an exterior wall which includes felt paper water-resistive barrier over wood structural panel sheathing. (The felt paper has been made translucent with separate pieces colorized to show how they overlap). The top layer of felt overlaps the lower layer by 2", and the vertical seam in the top layer overlaps by 6" in accordance with this section.