I chose pine to trim the windows with because it's my favourite and the shop cupboards and router table I made are pine.The vinyl clad windows were inserted from the outside and nailed into place through their flanges which are now under the siding. They were also screwed into the framing from the sides to keep them firmly in place.
This is what they looked like from the inside, before painting. There are three windows along the east side of the building.
Here is one of the sad looking windows, unfinished:
The great part about having a planer is that you can make your wood exactly the thickness you need it. I planed mine down to about 3/4" thick so that it would fit perfectly in the grooves the window had built in.
This is how the sill will fit into the groove when it's finished:
I decided on having a sill that extended past the outside of the window trim or casing by 1". Because of this, the sill piece has to be cut to fit into the groove as well as on the wall. You can see it here at the bottom:
Here's a close up, the window casing is 3 1/4" wide, so the "finger" on the sill extending out has to go past where the casing will sit by 1". It also is wider than the side and top jamb pieces, to allow the side casings to sit on it.
The side jambs will sit between the top and bottom pieces, of course everything has to measured precisely.
The previous photos show a trial fit with unfinished wood. Since I was trimming three windows and two doorways, I had a lot of pieces to cut and finish. I coated all pieces with five coats of wipe-on polyurethane.
The jambs are attached first, this shows the bottom sill and the side jamb:
When the jambs are nailed in, they have to have shims put in between them and the framing, to keep everything level and perpendicular. I also had to add some insulation in the space.
Next I put on the 3 1/4" wide side casings, all are 1/2" thick. Note that casings sit back from the jambs about 1/8" - 1/4", something I didn't know until I researched how to trim windows.
Here you can see how the side casing sits on the bottom sill:
For the top frame piece I glued a 1" wide piece of pine perpendicular to the top piece:
The top piece lines up with the outer edges of the side casings and gives a trim style that is different from the usual mitred corners.
The final piece is the bottom apron that sits below the sill and also lines up with the outer edges of the side casings.
The finished window:
Now I just need to make doors for two openings!
Showing this at the following blogs: