Solid core knotty alder door with schoolhouse casing detail, installed on T&G wall. One of the first jobs I bid, built and installed myself. This was winter 2105. See the sketch I submitted to builder below… first sketch also! Gluing up a blank for a large window sill. Inset basement window, case/sill. Casing had to scribe all the way around! Clean, tight miter with biscuits. Love the back-band. Had to install it with a 3/16” lap, per spec. Always line up the headers when your installing doors so the casings are level! Cutting down bifold doors to fit into opening that was framed 1/2” to narrow. I use a Kreg sled and track with my 6 1/2” Makita circular saw to achieve a flawless, straight cut. Then I clean up the edges with a sanding block to match the existing edge.