A step-by-step tutorial and budget breakdown for using IKEA Billy bookcases to transform his and her bedroom closets into custom, built-in style storage — plus an update on how these systems have held up after four years.
IKEA provides another affordable, clever storage solution—this time for small bedroom closets. We’ve used IKEA pieces for built-ins, home office storage, and pantry solutions over the years, but converting closets with Billy bookcases might be our favorite hack yet.
When the PAX wardrobe system wouldn’t fit our tiny closets, we switched to using Billy bookcases. The result: custom-looking built-ins that maximize storage and cost a lot less than a full PAX installation. Update: we built these closet systems four years ago and they’re still holding up beautifully.
Why the IKEA PAX System Might Not Work For Every Closet
PAX is great when dimensions line up, but in small or oddly shaped closets the standard PAX modules can leave wasted space or simply won’t fit. Billy bookcases are slimmer, modular, and easy to stack and trim to fill gaps and reach ceiling height — a smart alternative for creating a built-in look in compact closets.
Before this project we had old wire shelving that couldn’t store smaller items well and left shoes scattered across the floor. This Billy bookcase method creates organized, accessible storage that’s both attractive and economical.
How to Make a Custom IKEA Closet With Billy Bookcases
Supplies for a Reach-In Closet
- 1 — 31 1/2″ x 79 1/2″ Billy bookcase (white)
- 1 — 15 3/4″ x 79 1/2″ Billy bookcase (white)
- 1 — 31 1/2″ Billy height extension
- 1 — 15 3/4″ Billy height extension
- 8 — Skuggis hooks (bamboo)
- 1 — Pullout tie organizer rack
- 5 packs — Bumerang hangers (natural)
- 3 — adjustable closet rods
- 1 — 1×4 MDF strip for trim
- Finishing nailer and finishing nails
- Table saw or any straight-cut saw
- Caulk and wood filler
- Paint color-matched to IKEA white in satin finish
Estimated total cost: $324 (tools not included)
Below is the before photo of Robert’s closet — old wire shelving, little structure, and wasted vertical space.
Installation Steps for a Reach-In Closet
Step 1 — Empty Closet, Patch Holes, and Paint
Remove old shelving, patch holes with spackle, and paint the closet walls. Painting isn’t mandatory but a fresh coat makes everything look cleaner and reduces lingering odors.
Step 2 — Assemble and Place Bookcases
Assemble the Billy units per the instructions and place them side-by-side. In our reach-in closet they fit almost perfectly with only millimeters to spare — perfect for using every inch of space.
Step 3 — Add Extenders and Anchor
Add Billy height extenders on top to reach the ceiling and anchor the bookcases to wall studs for safety and stability.
Step 4 — Attach Trim and Close Gaps
Use 1×4 MDF to close the small gap between the top of the units and the ceiling. Cut trim boards to size and attach with a brad nailer so the assembly reads as a built-in unit.
Step 5 — Caulk, Fill, and Paint
Caulk all seams, fill nail holes, sand, and then paint over the caulk and filled areas with IKEA-matched white paint. You typically only need to feather paint over those spots rather than repaint the entire unit.
Step 6 — Add Shelves and Storage Accessories
Set plastic shelf brackets for shoe shelves and install accessories: closet rods, Skuggis wall hooks, tie racks, and Bumerang hangers. Customize with accessory dividers, jewelry racks, or a pull-out bar as needed. We added baskets later for seasonal storage, which fit perfectly on upper shelves and in cubbies.
Supplies for a Small Walk-In Closet
- 2 — 31 1/2″ x 79 1/2″ Billy bookcases
- 2 — 31 1/2″ Billy extensions
- 1 — Narrow PAX wardrobe frame for a back niche (if space allows)
- Komplement drawers and shelves for additional storage inside the PAX niche
- Komplement pull-out multi-use hanger
- Skuggis hooks and Bumerang hangers
- 1×4 MDF strips, L-brackets, finishing nailer, table saw, caulk, and paint
Estimated total cost: $464.50
Our tiny walk-in closet (more of a small L-shaped space) made the combination of 2 Billy units plus a single narrow PAX frame the most efficient option for hanging long dresses and adding drawers where needed.
Steps for a Small Walk-In Closet
Step 1 — Prep the Space
Remove existing shelving, spackle holes, paint, then position the PAX frame in any recessed niche intended for long garments.
Step 2 — Assemble Billy Units
Assemble two Billy bookcases and place them with a planned gap (we left a 12″ space) where a narrow shoe shelf or custom insert will go.
Step 3 — Stack Extenders and Anchor
Add extenders to reach the ceiling, then anchor all units into studs so they’re secure and stable.
Step 4 — Build Shoe Shelves from Leftover Shelves
Repurpose Billy shelves cut to size to create a slim shoe shelf for the gap, framing it with L-brackets and attaching to the adjacent units.
Step 5 — Attach and Finish
Install the cut shelves, trim gaps with 1×4 MDF trim so tops are flush with the ceiling, and finish by caulking, filling, sanding, and painting to match the IKEA finish for a seamless look.
Step 6 — Add Accessories and Organize
Install Komplement drawers and shelves in the PAX niche if used, add closet rods, hooks, and matching hangers. Use baskets as drawer substitutes for seasonal items. We added baskets later and haven’t missed built-in drawers.
Finished IKEA Billy Bookcase Closet
The Billy bookcase approach delivered a built-in look, more usable storage, and better organization — all for less than a full custom system. The project was straightforward; the most time-consuming part was editing a closet full of clothes to fit nicely into the new system.
Bedroom Closet Organizing Tips
Once your closet is built, these organizing strategies will keep it functional and tidy:
- Group clothing by type and season, and organize colors for a visually calm wardrobe.
- Turn hangers backward as an easy one-year purge system: donate anything not worn.
- Store frequently used items at eye level and use matching hangers for a cohesive look.
- Use shelf dividers and multi-hangers to maximize vertical space.
- Add motion-sensor or wireless LED lighting to improve visibility in darker closets.
More DIY IKEA Hack Ideas
If you enjoy repurposing IKEA furniture for storage, consider additional hacks like built-in bookshelves, dresser refacing, or creative closet inserts to match your space and needs.
