Installation J-channel is used around windows and doors to receive the siding. Follow the steps below when applying trim. Installation Steps Cut and bend the tab of the top piece of J-channel down to provide flashing over the side J-channel. Fold the bottom end of the side piece of J-channel inward at the bottom of the window, to fit over the existing J-channel to prevent water from entering under the sill. Cut the side J-channel members longer than the height of the window or door, and notch the channel at the top. Miter cut the free flange at a 45 angle and bend the tab down to provide flashing over the side members. A similar miter and tab may be provided at the bottom of the window, depending on the sill's condition. The J-channel should fit snug to the window. To trim the bottom of windows, and at the eave, J-channel can be used with the undersill molding inside the J-channel. The J-channel and undersill combination will secure the cut siding panel and help to keep the alignment straight. Dual undersill molding combines both functions into one part. Cut and secure dual undersill similarly to using J-channels. J-Channel Over Roof Lines Install the flashing before the J-channel to prevent water infiltration along the -intersection of a roof and wall. Installation Steps Keep the J-channel approximately 1/2" from the roof line. Chalk a straight line up the roof flashing to guide J-channel installation. Tip: You can use another J-channel laid over