The Only Way to Trim Exterior Windows
The key to durable trim and minimal trips up the ladder is to assemble it first and install it later.
Synopsis: Trimming exterior windows can be an ordeal, unless you learn the lessons that Seattle builder Mike Vacirca presents in this article. Vacirca’s process for exterior windows begins by assembling the trim first, then installing it as one piece. He starts by measuring every window to be sure he has correct dimensions. Vacirca then mills the windowsills, and is sure to keep the casing square during assembly. Finally, he installs the unit, nailing in the casing but screwing in the sill.
I can no longer call myself a trim carpenter because these days, I do a little bit of everything. I was a trim carpenter for most of the past 15 years, though, and a boat builder before that, so I feel comfortable saying that I know a thing or two about trimming out a window, and about how water affects wood.
Every time I dropped a piece of window trim from scaffolding 30 ft. in the air, I found myself remembering another career past, the days I spent working in a cabinet shop, where work is easy to control and weather isn’t a concern. Finally, I came to my senses when I was presented with 27 windows to trim for one house. That job helped me to develop a method for installing exterior trim that’s easier on my body, that is safer and faster, and that also yields more durable results. To make this process as efficient as possible, I even prime, putty, and paint the casings before installation.
Cutlists and stations add efficiency
When I worked in the cabinet shop, I organized my projects with cutlists and made shop drawings that showed how everything was going to be built before a saw ever touched wood. The process I created for assembling window trim in the shop starts with…