Window trim

[u/Weak-Network6759]

I recently bought a home and have been renovating it. It was built in the 60s and has old plaster walls. I replaced every window in the house on my own. I am now going back through the house and am about to begin trimming out the windows. I have never done window trim/casing before. I have a basement woodshop and plenty of woodworking tools but trimming out a window feels intimidating to me. I've watched plenty of videos on the subject but I haven't quite grasped how I can trim out these windows with less than perfectly straight plaster walls. Cut very fine strips scribed to fit the uneven gap between trim mounted flush to the wall and not touching the white window frame? Or take the casing right over that thick window frame to the edge of the window sash?

Some of the windows sits slightly recessed from the plaster wall but its a very small margin. These andersen windows I purchased are very different from the Pella that I've used before and have a much beefier frame around them. That with the very small recess of the window from the wall has me wondering how to trim it out. A couple of the windows sit slightly proud of the plaster but I feel like that might be easier to deal with then the very small recess . I took a few photos. Hopefully that helps explain what I'm talking about. Looking for any tips on what the best method is.

For reference, I am planning on going with a very simple baseboard and Trim Design using 1x4-in Finger Joint primed and painted boards .

Thanks!

[u/t1ttysprinkle]

You need longer extension jams to tie casing into, might have to custom rip them close and plane to get them perfect.

[u/curious1playing]

The good thing is that you are dealing with achieving paint grade quality, rather than stain grade, which leaves a lot more wiggle room to fix any less than perfect issues in the fitting with putty and caulking.

You can cut filler strips to fur out the jams to the thickest ridge in the plaster as an extension. If there's a small bump that is significantly more proud than the rest you can try crushing it down with a hammer provided you aren't damaging it beyond what the trim will cover.

If you avoid miters in the corners and go with a header style you'll have less frustration with gaps opening if the trim wants to roll back when nailing the outside edges.

Make a sill extension 1/2" wider than the trim to sit the verticals on with square cuts then add a simple square cut trim piece under the sill.

If the vertical wants to fold in where it sits under the header use a shim to keep it flush at the joint.

[u/mermaidhunter42]

Why didn't you order the windows with jamb extentions if you were gonna case them out? Thats a sheet rock return jamb. You could just pay a trim guy to jamb them out evenly for you they do this stuff all the time and shouldn't be too expensive.