Vinyl siding window trim: installation made easy

Vinyl siding window trim: installation made easy

When installing new vinyl siding, window trim, also called J-channel, must be installed before hanging siding panels. Although J-channel trim pieces are designed to prevent rain water from getting behind siding panels, for extra protection against water damage, you should seal the perimeter of each window with flashing tape before installing trim pieces.

Before trim and vinyl siding, windows should be sealed with flashing tape

The following instructions serve as a basic guide to help you through this process:

  1. Apply a strip of self-adhesive flashing tape to the bottom of the window frame. Completely cover any nail heads, as well as the seam between the window's nailing flange, and the home's water resistive barrier.

  2. Add strips of flashing tape to both sides of the window, again covering any seams. Extend the flashing tape a few inches above the nailing flange on the top side of the window, and completely cover the ends of the horizontal strip of flashing tape that runs along the bottom edge of the window frame.

  3. Apply the final strip of flashing tape along the top of the window, making sure to completely cover the nailing flange, as well as the top edges of the two vertical strips of flashing tape, which you previously installed.

Once you have sealed each window with flashing tape, you can install the J-channel trim pieces around each window. Follow the manufacturer's installation instructions that come with the J-channel you purchased.

After the J-channel trim pieces are installed around all the windows and doors, you can begin to hang the vinyl siding panels by inserting the end of the siding panels into the J-channel, as you work your way up the wall. In order to accommodate for the expansion and contraction of the siding panels, remember to leave a 1/4-inch gap between the side edge of each panel, and the inside of the J-channel window trim.




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