How to Fake Built-In Bookshelves With IKEA Billy (The Right Way)

My sister paid $6,400 for custom built-in bookshelves in her dining room. Mine cost $420 and every single person who walks into my living room asks who built them. The answer is: IKEA and me, mostly IKEA. Faux built-ins from Billy bookcases are one of the most dramatic DIY upgrades for the money, if you get the small details right. Getting those details wrong is why most Billy hacks on Pinterest look like, well, a Billy bookcase with some trim on it.

Why Billy works

The IKEA Billy bookcase is a 79" tall, 31.5" wide, 11" deep bookcase for $90. It's cheap, stable, comes in white or oak veneer, and — critically — is the exact dimensions and shelf spacing of a lot of custom millwork. Understanding the IKEA Billy bookcase's dimensions is a key step in our beginner guide to home organization for small spaces.

Line up two or three Billys, add trim, crown molding, and a painted-on baseboard, and they disappear into the wall like a built-in.

The supplies for a 3-unit built-in wall

• 3 IKEA Billy bookcases ($90 each = $270)
• Height extender units if you have tall ceilings ($45 each, optional)
• 1x2 or 1x3 primed pine for face trim — about $40
• Crown molding or simple cove molding for the top — about $28
• Baseboard molding to extend or match your existing — about $20
• Construction adhesive, nails/brads, wood filler, caulk — about $20
• Primer and paint — about $45
• Total: about $420 for a 3-unit wall

Step 1: Plan the wall

Measure your wall in inches. Divide by the Billy width (31.5") to figure out how many you can fit. Usually you'll have some extra space on one or both sides — that's fine, the side trim hides the gap.

Pick a spot where you have continuous wall (no windows breaking it up) and ideally at least two studs on either end. You want to anchor these babies to the wall — a loaded Billy can tip.

Step 2: Build the Billys

Assemble according to IKEA's instructions. Apply glue to the wooden dowels (Kallax and Billy are both known for loosening over time — glue fixes this forever). Tighten all cam locks firmly.

Don't install the back panel yet if you want the deepest "built-in" look — you can use a thicker backing material for better visual depth (see step 5).

Step 3: Position and anchor

Push all three bookcases flush against the wall. Slide them as close together as possible. They should touch or have only a hair gap.

Anchor each Billy to the wall using IKEA's included anti-tip strap AND one heavy screw through the back of the bookcase into a stud. Overkill? Yes. But these are now part of your wall, not furniture.

Pro tip: if your floor isn't perfectly level (welcome to an old Charleston house), shim under the Billy bases until the tops are aligned with each other. Mine required three different shim depths.

Step 4: Trim the face — the detail that sells it

This is where most Billy hacks fail. A raw Billy face has visible seams between units and a chunky 1" vertical edge. Both scream "IKEA."

Cut 1x2 or 1x3 pine strips to the height of the bookcases. Glue and nail them to:

• The vertical seams between each Billy (covers the gap and the visible edge)
• The outer edges of the outermost Billys (matches the interior seams)
• A full-width horizontal strip across the top (ties them together visually)

Suddenly the three bookcases look like one piece of millwork with vertical divisions.

Step 5: Upgrade the back panels (optional but transformative)

The back panels that come with Billy are flimsy cardboard. Replace or cover them with 1/4" beadboard panels or plywood painted the same color as the bookcases. This adds visual depth and makes the shelves feel more custom.

Alternative: peel-and-stick wallpaper on the interior back. See my peel-and-stick wallpaper review for brand recs — this is a perfect application because it's a small sheltered surface.

Step 6: Crown molding and baseboard

Crown molding across the top, matched to whatever molding style is in the rest of the room. Use small crown or cove — the simpler, the more "custom" it looks. Fancy ornate crown molding on a Billy hack looks fake.

At the bottom: extend your existing baseboard across the front of the Billy bases. If your wall baseboard is 4" tall, match it. This is the step that truly merges the bookcases into the wall.

Step 7: Caulk everything

Every seam. Every gap. Every tiny corner where two pieces meet. Paintable caulk, smoothed with a wet finger.

Caulk is the single biggest "quality of work" tell. Uncaulked Billy hack: looks homemade. Caulked Billy hack: looks like built-in millwork. I cannot stress this enough — I cover the same caulk-everything gospel in my board and batten accent wall post.

Step 8: Prime and paint

IKEA Billys come in veneered laminate that requires bonding primer. Zinsser BIN, two coats. My painting laminate furniture post covers the full reasoning — don't skip it.

Then two coats of a quality paint in a real color. Go bold. The whole point of this DIY is to look custom. A custom bookcase wouldn't be builder-grade white — it would be deep green, warm navy, soft black, inky charcoal.

My Billys are Farrow & Ball Studio Green (well, a Sherwin-Williams match, $48). Benjamin Moore Hale Navy, Sherwin Urbane Bronze, and Farrow & Ball Down Pipe are all tested favorites.

Step 9: Style the shelves

Finished but empty shelves look aggressive. Style them the way you'd style a coffee table (same rules from my how to style a coffee table post — varied heights, odd-number groupings, intentional negative space).

A mix: books (horizontal stacks and vertical groupings), decorative objects, art leaning against the back, a small lamp or two, baskets on the bottom shelf for hidden storage.

Leave 30-40% of each shelf empty. Overstuffed shelves look cluttered.

Lighting makes it professional

Optional but worth it: add picture lights above the top or small puck lights under each shelf. Even battery-operated puck lights ($20 for a 6-pack) take the whole thing from DIY to "designed." Illuminated bookcases read as actual cabinetry.

The mistakes I see most

• Skipping the trim covering Billy edges and seams — #1 tell
• Leaving the bookcases white instead of painting a real color
• Using ornate crown molding that doesn't match the rest of the room
• Not anchoring to the wall and floor
• Skipping caulk or priming
• Overstuffing the shelves instead of curating

One final warning

Once you do this, every blank wall in your house starts looking like it needs built-ins. I've got two more rooms on my list. My bookshelves have become Biscuit's favorite napping zone because the bottom shelf has a basket with a throw in it. He considers this his personal contribution to the design.

For $420 and a weekend, you can't beat it. Four hundred twenty bucks for something that genuinely changes a room. The rest is just patience with caulk and paint.