A system for sealing the gaps that occur along the perimeter of a building envelope, particularly along with installation of an exterior finish system channel, or screed, as occurs in the installation and application of stucco. It is common to have gaps occur between the channel, base plate, and foundation of the building envelope. The system utilizes a foam sealing element in combination with the channel, caulking, a fiberglass netting that is installed along the bottom of the channel and the face of the foundation, and, an adhesive sealant that seals and adheres the fiberglass netting to the foundation. The system includes several embodiments for use in either new construction or as an aftermarket product.