Double windows can look a little “unfinished” until the trim ties them together as one intentional feature. I’ve trimmed a lot of side-by-side windows in my workshop projects, and the right casing style can make them feel custom without getting fussy.
Reclaimed Wood Casing With Character
If you want texture, I’ve built double window casing from reclaimed boards and let the knots and nail holes be part of the story. I seal it well, and the patina makes the windows feel like they’ve always belonged there.
Useful items to consider:
- Clear Matte Polyurethane Wood Sealer: Protect your reclaimed wood trim while preserving its natural, rustic look with a durable matte finish.
- Black Wrought Iron Forged Nails: Add authentic detailing to your rustic casing by using decorative forged nails for that vintage aesthetic.
- Dried Pampas Grass Decor: Complement the natural wood textures of your new window trim with organic, neutral dried floral arrangements.
Classic Craftsman Plank Casing
When I want that timeless look, I build Craftsman-style trim with flat, wide side casings and a beefy top header that spans both windows. I’ve done this with simple 1x boards and it instantly makes double windows feel more architectural.
A few choices to try:
- Clear Pine or Oak 1×4 Lumber Boards: Build your flat side casings and headers with solid wood boards that stain beautifully for a natural finish.
- Matte Black Sash Locks and Handles: Create contrast against natural wood trim by installing these classic hardware pieces for functional, secure window operation.
- Black Steel Curtain Rod with Rings: Complete the architectural look with a sturdy, industrial-style rod that perfectly complements modern Craftsman window designs.
No-Miter Butt Joint Trim
If you’re nervous about angles, my go-to is no-miter window casing using clean butt joints and crisp reveals on both windows. I’ve taught this in workshops and it’s the fastest way to get sharp-looking double window trim without a perfectionist meltdown.
A few things you might like:
- Primed MDF Craftsman Molding Boards: Create the signature flat, clean butt joints for your window casing using these pre-primed, square-edge boards.
- Brad Nailer Kit: Secure your trim pieces firmly and cleanly without splitting the wood by using a reliable brad nailer.
- Paintable Acrylic Latex Caulk: Achieve a seamless, professional finish by filling gaps and nail holes with high-quality, paintable trim caulk.
One Continuous Header Across Both
A single, continuous header board across the pair is my favorite trick for making two windows read like one unit. I’ve used an extra-wide header casing before, and it made the whole wall feel taller and more balanced.
Possibly helpful picks:
- Wide Oak Casing Boards: Upgrade your window’s visual weight by selecting premium oak boards wide enough to span both frames seamlessly.
- Decorative Molding & Millwork: Add depth to your continuous header by layering decorative molding that mimics classic craftsman architectural details.
- Clear Satin Wood Finish: Protect your new continuous header while highlighting the natural wood grain matching the beautiful window trim shown.
Shared Stool and Long Apron
A shared window stool (the sill you can set things on) plus a long, simple apron underneath is such a clean, classic finish for double windows. I’ve replaced short factory sills with one long stool and it was the single biggest “wow” upgrade in the room.
Possibly handy products:
- Unfinished Oak Lumber Board: Craft a durable, custom-length window stool by starting with quality hardwood boards that are ready to finish.
- Primed Finger-Jointed Trim Board: Create a clean, seamless apron underneath your sill using these smooth, paint-ready boards for a classic look.
- Woodworking Clamps Set: Ensure a tight, secure bond when installing your new window stool and apron with these essential tools.
Thicker Casings for Visual Weight
When double windows look a little skinny on the wall, I bump the casing width up and keep the lines straight. I’ve done this in a plain room and the heavier window casing made the windows feel intentional instead of builder-basic.
Maybe worth checking out:
- Wide Natural Wood Dimensional Lumber: Upgrade your window frames with wider boards to create that substantial, custom look in your home renovation.
- Wood Conditioner and Stain: Enhance the natural grain of your new wider casings with a quality stain for a warm, finished appearance.
- Finish Nailer Kit: Secure your heavier trim pieces firmly and cleanly to ensure professional-looking results on your window project.
Center Mullion Wrap Trim
I like wrapping the gap between the two windows with its own little center casing so the pair looks neatly “stitched” together. I’ve used a slim center board with matching reveals and it made my double window trim look professionally planned.
A few suggestions:
- General Purpose Trim Boards: Create a unified look between windows by cutting this trim to specific lengths for a custom mullion cover.
- Construction Adhesive: Ensure your custom trim pieces stay securely attached to the mullion without relying solely on finish nails.
- Paintable Wood Filler: Achieve a seamless, professional finish by filling nail holes and gaps before applying your final coat of paint.
Crisp Reveal Line All Around
That tiny, consistent reveal line around both windows is what makes DIY trim look “finished” to my eye. I’ve accidentally skipped it once and immediately regretted it, because the double window casing lost that clean transition.
These products might help:
- Trim Reveal Gauge Tool: Ensure consistent spacing effortlessly; use this tool to mark perfect reveal lines before installing your window casing.
- Brad Nailer Kit: Secure your casing without splitting the wood; a reliable brad nailer helps keep your reveal lines precise.
- Clear Wood Stain/Finish: Protect that beautiful white oak grain and highlight your crisp reveal lines with a high-quality clear finish.
Farmhouse Trim With Slightly Proud Edges
I’ll sometimes let the header and stool overhang just a touch past the side casings for an easy farmhouse window trim vibe on double windows. I’ve done this with square edges and it reads cozy and handmade without being rustic-chaotic.
Check if these fit your needs:
- Clear Hardwood Boards (Oak or Maple): Craft your own custom window headers and stools using durable hardwood boards for an authentic, natural finish.
- Satin Wood Finish or Polyurethane: Protect your new natural wood trim while enhancing the grain with a smooth, durable satin clear coat.
- Brad Nailer Kit: Secure your header and casings cleanly with a reliable brad nailer for professional-looking, barely visible fastenings.
Trim That Aligns With Baseboards
I love when the window casing lines up with baseboards and wall trim so everything feels intentional and “designed.” I’ve planned double windows this way and it made the whole wall read cleaner, even before paint.
Explore these options:
- Wood Finish Stain for Trim: Create a unified look by matching the color of your window casing perfectly to your baseboards.
- Decorative Wood Flat Casing: Use flat, wide wood casing to mirror the clean lines of simple baseboards for consistent design.
- Laser Level for Alignment: Ensure your new window trim lines up precisely with existing baseboards for that professional, intentional finish.
Beadboard or Plank Trim Surround
I’ve wrapped double windows with a beadboard/plank surround and then capped it with simple casing for a cozy cottage feel. The mix of wall treatment plus trim adds depth without needing fancy moldings.
You might give these a try:
- Beadboard Panels or Planks: Instantly add texture to your window jambs by applying these classic grooved panels for cottage charm.
- Oak Board Lumber: Create durable, warm window sills and simple casing headers using solid oak boards for framing.
- Linen Curtain Panels: Soften the structured look of wood trim with these breezy, textured drapes that filter natural light.
Extra-Deep Stool for a Display Ledge
One of my favorite upgrades is making the window stool deeper across both windows so it works like a little shelf. I’ve done this in a sunny spot and it turned the double window trim into a practical display ledge.
Consider these options:
- Ceramic or Clay Minimalist Vases: Style your new window ledge with neutral vases that add height and elegant texture to your sunny display.
- Natural Dried Pampas Grass: Bring organic warmth to your deep window stool by displaying fluffy dried botanicals for a soft, natural look.
- Unfinished Hardwood Boards: Create a custom extended display ledge by selecting sturdy hardwood boards ready for sanding and staining to match.
Built-In Shelves Tied Into the Trim
For a true statement, I’ve extended the side casings outward and blended them into shallow shelves so the double window trim becomes part of a mini built-in. It looks custom, and I love how the casing lines keep everything feeling clean and intentional.
Might be a good match:
- Solid Oak Wood Lumber Boards: Source high-quality hardwood boards to construct durable, custom shelving that perfectly matches your window trim aesthetic.
- Decorative Cabinet Door Hinges: Install traditional hardware on your built-in lower cabinets to add a subtle, classic finish to the woodwork.
- Matte Wood Varnish or Sealant: Protect your custom built-ins with a clear matte finish that enhances the natural grain without adding unwanted shine.
Hidden LED Glow Behind the Header
This one surprises people: I’ve added a small spacer behind the top header to create a pocket for soft hidden lighting above double windows. The trim still looks classic in daylight, but at night it gives a gentle glow that feels seriously high-end.
Try these:
- Waterproof Exterior LED Strip: Choose weather-resistant, warm white LED strips to create that inviting, gentle glow above your outdoor window trim.
- Low Voltage Landscape Transformer: Power your new window accent lights safely and efficiently with a reliable outdoor-rated low voltage transformer unit.
- Aluminum LED Channel Diffuser: Install these channels to protect your light strips and ensure a smooth, spotless line of illumination without glare.
Mixed Materials: Wood Trim With Metal Inlay
When I’m craving something unexpected, I route a shallow groove in the header or center casing and set in a thin metal inlay strip. I’ve done this on double window trim with a matte finish, and it’s that subtle modern twist that makes people stop and stare.
You might like:
- Brass Flat Bar Strips: Add a luxurious, modern accent to your wooden window trim by embedding these durable metal strips.
- Palm Router Tool: Carve precise grooves into your window casing effortlessly to prepare the perfect space for metal inlays.
- Clear Polyurethane Finish: Protect your new mixed-material trim and enhance the natural wood grain with this durable, lasting sealant.
