Install Window Trim Over Siding

Face nail trims using 2 inch 16 gauge finish nails after every 16 inches apart.

Install window trim over siding.

If the trim is being applied over the hardi panels. Building paper is an important part of the wall s waterproofing. Slide the top edge under the window fin then nail off the fin with roofing nails. 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.

Touch up the divided hardie trim boards before trimming them to your window. The head flashing is installed in a bed of caulking onto the top of the window frame. The rain screen battens are run down to the top of the window flange. In order to get the most accurate cut line we decided to place our new window in the opening to trace it.

Level and tack the new window in place then cut a piece of aluminum flashing to width so it extends from the new window to overlap the nailing hem of the siding below. The wrb is lapped over the head flashing or the flashing is taped. 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. 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.

The cement board panels are fastened to the battens. Before you replace the siding cut and install new j channels to prevent water from leaking into your home. 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.