Now that we have wrapped the house, strapped the house, and installed our flashings it is time to install the trim. The trim is installed first before the siding is that because the trim is typically 1 ¼” thick and the siding is ¾” thick, thus the trim is thicker. This allows the siding to fit nicely into the trim which creates a nice caulking joint. Starting with your corners, and moving to windows and doors allows you to start your first siding course while moving up your walls.  Above every window and door trim requires a piece of starter strip and/or an L strip to ensure your siding has something to sit on and adequate ventilation occurs.