Casing Bead J Channel is used to provide a smooth transition from the stucco limit to the windows, doors or other dissimilar materials. It also provides a gradual transition to allow moisture to drain away from the structure.
To avoid risk of moisture or water penetration J channel should be installed for future application of caulk, wherever stucco is united with other surfaces ( windows, doors, stone, siding ). Backer road foam is also required for the support of caulk.
