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.
