Step 1: Plan Your Built-Ins

The recessed area around the window was only 17 inches deep, and at first its offset position and sloped ceilings felt challenging. But the limited depth actually suggested a built-in solution. That blank wall needed storage and visual interest, and a built-in felt right for both.

We used Ikea’s kitchen planner to mock up cabinet layouts. After experimenting with a few options and layering some shelf ideas in Photoshop, we landed on four standard 30″ tall base cabinets across the run with a centered 20″ drawer base under the window to create a window-seat effect. Once the layout was finalized in the planner it produced a parts list we could use for ordering.

Step 2: Assemble Your Ikea Cabinets

First assemble all the cabinet boxes following Ikea’s instructions. We skipped installing doors and drawer fronts for now. If you need help, there are many tips for installing Ikea kitchen cabinets that can save time and frustration. This is also a good moment to verify that the assembled boxes match your plan and will sit correctly in the niche.

Step 3: Build Cabinet Bases

The standard Ikea legs were too tall for the low window, so we built custom bases from stacked 2×4 and 1×4 boards to achieve the perfect height. These bases primarily provide a surface to attach the toe kick or baseboard later, and they give the cabinets a little extra support and protection if kids climb or play near them.

Step 4: Attach Cabinets To The Wall

Ikea cabinets hang on a metal rail system: mount the rail level to wall studs, then hang and secure the cabinet boxes. Use a stud finder and a reliable level to position the rail. For our shallow niche we fastened a 2×4 into the studs behind the rail to give the 12″ deep cabinets a bit more depth and a sturdy surface to attach to.

Step 5: Add Filler Pieces

With cabinets hung (but not fully locked), add filler pieces between boxes so the run appears as one continuous built-in. We cut wider fillers to account for the off-center window and installed them with clamps and screws. You can buy Ikea filler strips or use pre-primed wood and trim them to size. We also added fillers alongside the window to hide the metal rail.

Step 6: Add More Filler Pieces

The first layer of fillers sits flush with the cabinet boxes but not with the doors, so we added a second, thinner layer to mimic the door faces and achieve a custom look. Match the edge profile of your doors — for our BODBYN doors we sanded a slight bevel into the filler edges so everything read like one coordinated unit. We glued these pieces and painted everything to match the Ikea white.

Step 7: Add Toekick or Baseboard

We installed baseboard beneath the cabinets, nailing into the 2×4 supports built earlier. On our low cabinets we had to rip the baseboard a bit narrower, but on standard-height installs this step is usually straightforward.

Step 8: Add Counters

We considered wood countertops but chose to keep the whole run white for a cohesive look. We used wood project panels sized to cover each cabinet section, primed and painted them to match the cabinet finish, then screwed them in from inside the cabinets. Allow the tops to fully cure before placing heavy items on them.

Step 9: Add Cabinet Hardware (Optional)

Finally, add matching pulls or knobs to doors and drawers if you like. Installing hardware is an easy finishing step that ties the whole built-in together.

Once the cabinets were complete we turned our attention to the floating shelves to finish the niche and make the room feel polished.

For the full before-and-after of the bonus room and all finishing details, see our project write-up.

More Built-In Cabinet Projects

We’ve completed several built-in projects using stock cabinets, so if you’re looking for more ideas consider exploring other DIY transformations such as hacking Ikea Besta, creating built-in bookshelves from cabinet units, converting dressers into bases, or adapting Pax wardrobes to look built-in.

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