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  • Writer's pictureMatt Weber

Craftsman Trim for Window Casing

Updated: Sep 16, 2021

DIY'ers might appreciate the simplicity of the cuts and assembly when installing Craftsman style trim, because it eliminates miter joints and complicated angles in favor of straight 90-degree cuts and square dimensional boards.

Craftsman style carpentry originally emphasized simpler, hand-crafted trim made by skilled craftsmen from local wood. As a rebellion to the industrialization of the late 1800s, the craftsman style focused on the materials rather than fancy shapes. Therefore the trim pieces are usually flat, but different sizes are used to provide variety and dimensional detail.

This simpler style makes a more natural transition to rustic interiors than the more formal neo-classical or Victorian trim styles with their elaborate fluted columns, beads and dentil patterns.

Make a Plan

To my knowledge, there is no rule-book to guide your trim design. It’s up to you to create your plan according to your taste and preference.

In this case, I had installed a nice new Weather Shield Premium Series Double-Hung Window in a kitchen. It needed a little dressing up, and craftsman style trim would work best for the space, which was otherwise decorated with rustic or industrial-style decor.

On the interior side of the window, I wanted a double-layer head cap, which I think is a cool “regal” look without appearing too highfalutin. I started with that idea, then decided the smaller of the two cap layers would look good as a horizontal accent at the top and bottom of the window, providing depth and shadow lines. I sketched the design on paper, and since I was working with 1x boards which measure 3/4-in. thick, I decided to use a 3/4-in. reveal between all the trim layers. I purchased boards in various widths that would achieve this 3/4-in. reveal, as you can see labeled in the photo.

That’s basically all there was to my plan.

Quick Tips

  • Sketch your design on paper. Keep the casing design symmetrical, with the widest trim pieces situated at the top of the window.

  • Boards mounted flat against the wall can be made of MDF but the boards installed parallel to the floor, such as the window stool, should be made of a more durable solid wood because they will project into the room and be more susceptible to impact.

  • Paint and assemble as many of the trim components as possible prior to installation.

  • Reduce touch-up work by relying more on glue and less on fasteners.

  • Fill all fastener holes with vinyl spackling but fill all joints and seams with a flexible, paintable caulk/sealant.

Installation Basics

I pre-assembled the 2-piece head cap using wood glue and countersunk screws.

I did the same to make the 2-piece apron from 1x2 and 1x4.

I leveled the window apron and fastened it flush with the bottom of the window using 2-1/2" finish nails.

Next, I added the 1x4 verticals. Keep a close eye on the reveal between the trim pieces and the window so everything matches all the way around.

To firmly attach the 1x2s, I countersunk a few 2-1/2" self-drilling Fine Screws from U2 Fasteners. The small head of these trim screws makes it easy to conceal with spackling.

The final 1x3 makes its appearance.

I attached the pre-assembled head cap with more Fine Screws.

For paint-grade projects, finish up by spackling all fastener holes, but use a flexible, paintable caulk to seal the joints and seams between boards. Complete the project with a little touch-up paint.

Take Me to the Other Side

The opposite side of this kitchen window opened onto a covered, screened porch. I basically duplicated the same trim style there as on the interior--until I got to the window sill.

There, I installed a modified window apron to serve as a drink shelf for folks hanging out on the porch. There's nothing revolutionary about the shelf design, but I did add a nosing strip to ensure drinks didn't slide off. I also used my router to round a bull-nose along the edge of the nosing to prevent injury from anyone bumping into it. I built the shelf just wide enough to hold a beverage and supported it with three 90-deg. triangular brackets. Because it projects into the room and is susceptible to damage from moving furniture, etc., I built the shelf from hardwood--an inch-thick reclaimed cherry stair tread, in fact--which is reason #1,001 why I never throw away quality wood material.

The outside of the new window was surrounded by damaged siding from the removal of the old window. Before I began trim installation, I installed "filler boards" in place of the removed siding to build out the material around the window to a flush, even plane on which to install the trim pieces.

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