Water By-Passing Window Perimeter Joints

By: Dominic L. Pusateri 

Perimeter caulk, also known as sealant, is used to transition windows to adjacent claddings; we call this a perimeter isolation joint.  The windows and claddings resist water and air infiltration with the help of the weather resistive barrier (WRB) at the cladding substrate.  The area between the cladding and WRB is known as the drainage plain.  In a recent blog post, I defined and quantified the volume of water that the drainage plain should be capable of managing.   Water at the drainage plain is commonly referred to as incidental water.   The incidental water should be controlled and directed to the exterior.  The interfacing of the weather resistive barrier at openings in the wall is critical but, because the weather barrier interfacing occurs behind the surface of the cladding and abutting components, it is often undervalued.  

What is Incidental Water Anyway?

By: Dominic L. Pusateri

Incidental water is a term used in the building codes and referenced in specifications but what constitutes incidental water?