Install Window Trim Over Siding

This meant our new windows would have trim that was much wider than our old windows making it necessary to cut away a bit of our siding to sit flush with the edge of that new trim.

Install window trim over siding.

Make sure that a drip cap is installed first over the window before going for the hardie siding. Cut the horizontal piece to size and snap it in place over the vertical moldings. You will see the trims lay nice and flat. We used pressure treated 2 x 4 s for the trim around the windows and the doorway and then we had to create trim corners for both the inside and the outside corners like the ones in the picture above.

Slide the top edge under the window fin then nail off the fin with roofing nails. Before you replace the siding cut and install new j channels to prevent water from leaking into your home. The rain screen battens are run down to the top of the window flange. If the trim is being applied over the hardi panels.

The head flashing is installed in a bed of caulking onto the top of the window frame. Building paper is an important part of the wall s waterproofing. The wrb is lapped over the head flashing or the flashing is taped. Here is one great way to trim out a window or door opening with aluminum coil when using progressive foam insulation for plank style sidings such as fiber ce.

Face nail trims using 2 inch 16 gauge finish nails after every 16 inches apart. If we installed the trim after the siding we would have had to caulk a ton to fill in for the different levels the layered siding creates. In order to get the most accurate cut line we decided to place our new window in the opening to trace it.