The function of T-Stop is simple: Its primary purpose is to prevent the spray foam sealant from blocking or damming the area designed as a drainage area for incidental water entering the assembly. The purpose for flashing the rough opening prior to installing a window is to redirect water to the exterior of the building envelope. When the foam reaches the nailing flange, it prevents the water from reaching the sill location where intended for draining. When properly installed, T-Stop will prevent the expanding foam from reaching the nailing flange, and in the process maintain a free draining air cavity at the perimeter of the window.
The space between the window frame and the rough framing material is not an accessible space. Therefore, it is not possible to inspect that space once the window is installed and the foam sealant is set inserted. T-Stop, when properly installed, is the most reliable method of maintaining the free-draining air cavity for water drainage.
T-Stop is currently available in 8.5-ft. lengths (+/- 1").
T-Stop Patent Numbers: 8,302,353, 8,745,939, 9,038,334, 9,422,762, 9,945,172