DIY Billy Bookcase to Built-In: Step-by-Step Beginner’s Guide

In this step-by-step beginner’s guide, I’ll show you how I transformed a basic Billy Bookcase into a stunning built-in that looks like it was custom-made for my home.

I needed some storage space in our small guest room and only had room for one narrow bookcase. To maximize that space and make it look good in that tiny room I decided on giving a simple Billy bookcase a makeover. I transformed a basic bookcase into a beautiful custom built-in that utilizes the height of the room to the max.

two images of finished and process of building a ikea billy bookcase built in with text overlay diy ikea billy bookcase built in a beginners guide

I am no builder, but if I can do this project then so can you. I hope you enjoy my Billy Built In Tutorial for Beginners.  

How to Make a Billy Bookcase Look Built In

If you’re looking to add some built-in storage to your home, the IKEA Billy bookcase hack is a great option. With just a few basic materials and some simple tools, you can create a custom built-in look that will be the envy of all your friends.

I only used one bookcase with two top extensions. But I have seen beautiful examples of DIY built in bookcases that involve several units.

empty wide bookcase built in to custom fit a corner of a room

This IKEA hack was pretty intimidating for me at first. But it was actually a fairly simple process. With some logical thinking, the most basic woodworking skills, and a little bit of patience, I was able to pull it off. 

So follow along with my building adventure and at the end of it, you will know how to make your own Built-in Billy Bookcase too, and how to avoid my mistakes!

My bookcase lived the first 10 years of his life as a very ordinary Ikea Billy Bookcase.

plain brown billy bookcase filled with books and with an empty extension on top

Everyone knows Billy, don’t you? He has been a house guest in many homes all over the world for almost 50 years now. All in all, about 120 million Billy’s have been sold to date. 

Well, this particular Billy was at least 10 years old, but still going strong. Just plain boring, like Billy kinda is. But it fit perfectly just behind the bed in our tiny guest room. So I wanted to keep it but make it look a bit less, yeah what, ugly I guess.

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Step 1: Materials and Tools

Before getting started on the project, let’s make sure we have all the necessary materials and tools. Here’s a breakdown of what I used:

Materials:

  • 1 standard IKEA Billy Bookcase
  • 2 Billy extensions
  • Trim (crown moulding and shoe moulding)
  • (optional) additional MDF or plywood to fill up extra space
  • Small wood screws 
  • Hammer or nail gun and nails
  • Wood glue
  • Wood filler
  • Paint or stain

Tools:

  • Drill and drill bits
  • Level
  • Saw (table saw, circular saw or miter saw)
  • Sander
  • Paintbrush or roller
  • Caulk gun

Please keep in mind that I was building a custom Billy for the space I had available in my guest room. I could move up but not sideways. You might not need two extensions, but you could maybe accommodate two or more Ikea Billy bookshelves side by side. Make sure to measure your space and plan accordingly.

Now that you have all the necessary materials and tools, it’s time to move on to the next step.

four images of the stages of creating a billy bookcase built in

Step 2. Prepare Your Project

If you want to turn your Billy bookcase into a built-in, there are a few things you need to do before you get started. Here is a small list:

  1. Plan your design: Before you start, you need to have a clear idea of what you want your built-in to look like. Consider the size and placement of your bookcase, and think about how you want to integrate it into your room. You may want to sketch out a rough design or use a design tool to help you visualize your project.

    Sidenote: I of course totally skipped this step. My billy built in was so basic that I didn’t need to make detailed plans. But take my word for it, if your project is more complicated than take to time to visualize and plan your project.
  1. Measure your space: Once you have a design in mind, you need to measure your space to make sure your bookcase will fit. Measure the height, width, and depth of your bookcase, as well as the height and width of the space where you plan to install it. Note where there are light switches or electrical outlets that you have to take into account. And remember that Billy Bookcases come in varying heights and widths and there are vertical extensions available.
  1. Choose your materials: To turn your Billy bookcase into a built-in, you’ll need some additional materials, such as wood trim, paint, and hardware. Choose materials that match your existing decor and that will help your bookcase blend seamlessly into your room.
  1. Set up your workspace: To make the process of turning your Billy bookcase into a built-in as smooth as possible, you’ll need a clean and organized workspace. Set up a table or workbench where you can cut and paint your trim pieces, and make sure you have all the tools and supplies you need within reach.
  1. Remove obstacles on the walls. Remove the baseboard and shoe molding from the wall where the bookcases will be installed.
  1. Assemble the IKEA Billy Bookcases. When putting the Billy bookcase together it is optional to adhere to back of the bookcase. I did, because I had plans for it, but if you can attache the bookcases securely to the wall you can also opt to leave the back out.

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Step 3: Putting Your Built-in Bookcases Together

  1. Assemble the Billies and the extensions and put them in their place
  2. Add base, and crown moulding. 
  3. Hide the seams with shoe moulding
  4. Add extra shoe moulding on the front and underneath the shelves for an extra pretty look

I already had a plain old Billy to start with. My first step therefore was to go to the clearance section at Ikea and buy myself two extensions to put on top of the Billy. I didn’t care about the color because I knew I’d be painting it anyway.

billy bookcase with two stacked extensions in a corner of a room

After assembling the bookcases I attached them to the wall. Here in Europe that means drilling a hole in a concrete or brick wall. For you, it might mean looking for the stud in the wall and using anchors to secure the Billy bookcase built-ins.

I also bought some MDF to fill up the space between the top of my extended bookcase and the ceiling (we have an old house with high ceilings), a nice long stretch of crown moulding and various small wood trimmings and started cutting.

Figuring out how to cut the crown moulding so that all of the corners fit together nicely was the hardest thing of it all. I used up that 2.5 m (about 2.7 yards) almost completely before I had it right.

I would try to explain it here, but in the end, trial and error works best, oh and searching YouTube for videos on how to cut mitered corners in crown moulding also helps.

closeup of ikea bookcase with crown and shoe moulding

I screwed a little wood against the wall to help keep the MDF up and prevent it from caving in. Then I used liquid nails to glue everything in place and as you can see some painter’s tape to keep it in place while the glue dried. I could have used clamps too, but this was easier.

You can also see here, that there were some gaps and cracks left, but I wasn’t worried about those because plaster and caulk would seal those up nicely.

I concealed the crack between the MDF and the bookcase with a small piece of shoe moulding. And I applied some decorative wood to the front as well.

Because of my lack of experience, it took me about one day of work to get to this point.

Step 3. Making Your DIY Built-ins Look Pretty

  1. Caulk any seams, gaps screw holes, and nail holes
  2. Sand and clean the built-in
  3. Paint the bookcase in your color of choice
  4. (optional) decorate the back of the bookcase with an accent color, wallpaper or beadboard

Now came the fun part. Making the Billy built in look pretty and cohesive.

close up of white beadboard wallpaper inside ikea bookcase shelves

I covered the back of the bookcase with beadboard wallpaper. If you plan to wallpaper the inside of your bookcase too, beware of this:

On the first try my wallpaper shrank after I had applied it to the back. Turns out that wallpaper paste needs to be able to suck into the wall it is pasted on. You need a background with absorbent qualities. And a laminated bookcase back does no absorbing whatsoever. The pasted wallpaper dries up unevenly then and the edges shrink. 

To prevent this disaster from happening again I sanded the heck out of the backing and applied it again. This time it worked.

When I used wallpaper to decorate an old wardrobe I adhered it onto pre-cut panels with double-sided tape. That worked wonders too.

close up of gaps in billy bookcase built in filled with caulk

Ok back to my built-in. Next up was caulking, a lot of caulking.

As you see here, all the cracks and crevices were already practically invisible after the caulking.

billy bookcase with shoe moulding underneath the shelves and holes filled with wood filler

As a final step in this phase I glued some fake supports for the shelves with wood glue and filled up all the little tell-tale holes with wood filler.

And here she is after all that. Ready for her first paint job.

built in billy bookcase with two extensions before painting

Painting a Billy Bookcase

I used a quality primer as a first step in painting the bookcase.  Because of all the combinations of materials: laminated wood, raw wood, MDF I needed something that would stick to anything. Make sure that you let a primer like that cure long enough or it won’t do its job properly.

For the finish, I choose a white with a grayish undertone. I gave the whole bookcase, including the beadboard wallpaper two coats of paint.  And it immediately looked wonderful.

close up of corner of white painted billy bookcase built in extension

Except that it is so difficult to get a good shot of all that white-on-white. The camera had nothing to focus on. So you are not able to enjoy the full effect of how wonderful it looks.

But it does. The bookcase totally blends in with the room now and looks as if it was built especially for that spot (which in fact it kind of is).

And yes I know there is still a gap between the bookcase and the left wall. I hate it too. But in our old house, the walls aren’t straight and I just couldn’t figure out a way to cover it up that would still look good. So I decided to live with it. After all, done is way better than perfect.

full length white painted billy bookcase built in empty

Decorating the Billy Bookcase

And then the real fun could begin.

Decorating my built in Billy and finally finding a home for the stacks of books that were laying around. 

full length ikea billy bookcase built in styled with books and accessories

I followed some basic design rules when I styled my bookcase. You can read all of my tips on how to dress a bookcase here. 

That’s it folks! Project done and dusted.

It was a learning curve for sure, but doing this project has given me so much confidence for projects to come.

I hope my beginners guide to turning a Billy into a built in was helpful. 

Have fun DIYing and Decorating!

Songbird | Website | + posts

Marianne Songbird is the founder of Songbird, where she hopes to inspire everyone to create a home they love, one DIY project at a time. She shares anything from craft ideas to home decor inspiration and from DIY projects to decorating hacks. Originally from the Netherlands Marianne and her husband Lex are currently renovating a 250-year-old farmhouse in Germany.

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60 Comments

  1. Brilliant! All of your hard work paid off. Who would have thought that Billy could look so dashingly handsome?!

  2. Anne aka La Vie en Rose says:

    I am your latest follower so hello! Fantastic job on that book case. It totally looks built in. Sorry you had to go through the wallpaper trauma to get there though. I feel inspired to go white for a while in my non furnished living room.

  3. Joke van de Klift says:

    Dag, Marianne
    Ik vind het nogal wat, schitterend en erg knap wat jij gepresteerd hebt, ik doe het je niet na!
    Ik vind het ook erg mooi geworden.
    Lieve groet,
    Joke.

  4. Miss Mustard Seed says:

    It looks so great and was so clever of you! The "frakenshelf" look fabulous when it's all painted out. One would never know that it's not a built-in. Great work!

  5. Kelee Katillac says:

    Great demo!

    We need pre-pasted papers, though! I love the look of your shelf….well done!

    love, kelee

  6. Rhoda @ Southern Hospitality says:

    Hi, Marianne, I'm so happy to see your project, so that I can get an idea of all that went wrong! I'm SO bummed that they have discontinued the pre-pasted version. I'm totally going to write the GB company and tell them what a mistake this is. I've called already, but I need to get someone higher up to listen. I totally don't understand why they changed a good thing. Crazy!

    Anyway, your Billy bookcase turned out fabulous, I love it. In spite of the troubles. Looks great! I'm jealous of your miter saw, I want one too. Thanks for sharing your project with me. I don't know if there is anything I can do, but I'll sure try.

  7. Erin The Apartment Homesteader says:

    this looks amazing! way to think outside of the box (:

  8. Jennifer Juniper says:

    THis looks so fantastic! Who would have guess his former life? How did all of us do projects before we made bloggy friends?!?

  9. Het ziet geweldig uit. Trouwens heb je gedacht aan een sierlijstje of latje om de ruimte tussen de muur en de kast te maskeren?
    groetjes,
    Marianne
    P.S. Ik zou deze hack insturen naar Ikeahacker.blogspot.com

  10. marty (A Stroll Thru Life) says:

    Oh I think it looks fabulous. I love the built in look. You did such a fabulous job. Great tutorial too. Hugs, Marty

  11. Maryann @ Domestically-Speaking says:

    It turned out wonderful! Sounds like it was a chore to get there though. I've got a roll of their beadboard wallpaper, but I think mine is the pasted… I'm hoping!

  12. Manuela@TPOH says:

    That looks great! I know Billy very well LOL I love IKEA! Sorry to hear about the wallpaper. I wonder what made them decide to change it?

    Manuela

  13. Shel at Dreamy Nest says:

    Great job! So proud of you for learning how to use a compound mitre saw! Isn't it empowering!? I just learned how to use one myself and I love it!
    I also love how you shared what NOT to do. 🙂
    Came over from the #FF from Beth at the stories of A to Z. Following you now.

  14. wow! I love it, and I'm so glad you shared it with us. Yay! miter saw owner! Don't you LOVE it? You can do so much now. There's no stopping you!
    where the wall meets billy… I have two suggestions if it bothers you. I'm not bothered by such things, but in case you are. It's hard to tell exactly how much room is there without seeing it in real life.
    One suggestion is painter's caulk. (probably like you used for the crown molding) the other is some trim, possibly cove.
    I have the same problem in my bedroom where I just put down new baseboard. (bad walls) there is a gap, but it's pretty wavy.
    again, I just have to say awesome job! I'm so happy that your billy is no longer recognizable! 🙂
    gail

  15. Shel at Dreamy Nest says:

    Well – Google Friend Connect seems to be down. Remind me on Twitter to come back and add you so I can keep up with your posts.
    Many blessings!

  16. Ginger@cottageonrosewood says:

    Genius…I love it!

  17. Beth@The Stories of A2Z says:

    It looks fantastic and I think it was totally worth it! Yay you for tackling, conquering, and mastering such a major project. I used unpasted beadboard wallpaper in my boys' room on drywall and it still shrunk a bit. I was able to caulk the gaps and make it work, but I think prepasted would have been WAY better!

  18. Your bookcase looks wonderful. Thank you for posting about the unpasted bead board wallpaper, I did not know about the shrinkage.

  19. Mary Ellen says:

    Wow these are super!! Thank for the heads up about the wallpaper shrinking! I am wondering if you could use that spray adhesive on it. I used that when I papered my china closet with old music sheets.

  20. That looks SO great!! I used beadboard wallpaper on a shelving project too and I LOVE IT. Ours was prepasted… in fact, that's all the hardware store carried. I wonder if it's just a certain brand that stopped carrying it?

  21. Hello!
    Good work, Marianne! What a beauty your Billy is now!!

    Billy lives in our family, too. He is quite old and full of books. But I do not like his colour anymore, so I was about to get rid of him (yeah, have to say "him" instead of "it"…). I'vebeen thinking about to paint it, but…. THANKS for all this information!! I think, I'm going to try, too.

  22. Miss Marple says:

    Gigantisch meid!…Ik zie nu al beelden van mijn gepimpte Billy boekenwand voor me…wanneer kom je? 😉
    Een heel fijn weekend – Irma

  23. Tarnished and Tattered says:

    I love this!! What a frugal way to achieve beautiful built-ins. There is nothing better than elivating the ordinary into something extraordinary. Kudo's on the power tool use. I don't know how you did the tricky computer thing to switch back & forth to the before & after but it's almost as cool as the billy built-in! Lisa

  24. Brenda@Cozy Little House says:

    It looks fantastic, Marianne! Now I know why you wanted that wallpaper. I'm so sorry you had such a problem with it though. And after working so hard to find a way to get it too. But the end result looks simply phenomenal!
    Brenda

  25. Sweet as June says:

    I love all your creaive ideas! Thanks for being my newest follower!:)

  26. Anonymous says:

    Hallo Marianne. Die kast is prachtig geworden, ik ben benieuwd hoe hij er in 't echt uitziet.
    Doei, Ans

  27. Catharina Maria says:

    Wat een prachtige kast is dit zo geworden , compliment !!
    Lieve groet ♥RINI♥

  28. Korrie@RedHenHome says:

    Good for you! I bought my first miter saw about a month ago, and I still haven't been brave enough to use it!

  29. sportzmom says:

    That is awesome. I think I might be too chicken to undertake this project!

  30. I just wanted to stop by and let you know that I linked to this post today from the new Home & Garden channel at Craft Gossip. 🙂 My hope is to share many of the fabulous projects I see everyday with the vast CG audience. I hope you will not only stop by and subscribe to CG, but will tell your friends about the new category! Hope you see some traffic from it!

    Your feature will appear in the main Craft Gossip RSS feed, on the main home page and can be found directly here
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  31. InMyOwnStyle says:

    Hi Marianne-

    It was worth all your effort!!! What a difference – kinda like Semi-Homemade. You know that show where she uses store bought food and makes it look like she made it from scratch. Your Billy Bookcase now looks like a custom carpenter was at your home. You must love it.
    My best – Diane

  32. You totally rocked it!!!!! It looks just lovely…and I'm so proud of you for learning to use that saw. I'm looking into taking a woodworking class myself this winter….hoping to overcome my own fear of powertools 🙂

    It just looks stunning. Great job!

  33. the cape on the corner says:

    that looks great! glad you conquered your miter saw fear and just went for it. it really look fantastic!

    coming over from diy show off

  34. Fabulous!! You did a lovely job!
    lifeofperks.blogspot.com

  35. Just found this post whilst looking for ideas on what to do with my dire bookcase situation and this is the answer I've been looking for! It looks great and I'm definately going to be trying the beadboard wallpaper out too to give it a bit of ooomph! Sadly I'm in the UK so limited options here too. Although I am going on holiday to the US soon……
    x

  36. Wow, it is really amazing! Would you mind telling me, which kind of paint you used? I also get an ugly brown billy, which I want to make white.. ThanX…

  37. Linnea "Ea" Grönstrand says:

    Definetly worth it – two thumbs up for new-and-improved Billy 😀

  38. Anonymous says:

    Thanks so much for this post. I was going to use crown molding to add more height to a bookcase for it to reach the ceiling, but I still needed more height. I didn't know what to do, so I did a seach and found your post. You saved me from having to using a gigantic piece of molding that would've made it look weird.

  39. Anonymous says:

    Great job….and thanks for all the detailed instructions. You could use caulk along the left edge of the bookcase and it would just blend the wall and bookcase together and not show at all. My white kitchen cabinets were filled like this where they met the wall; it produced good results. The off-kilter wall disappears.

  40. Anonymous says:

    Great job! The space between the wall and the case could be fixed by using a strip of narrow moulding and then painted…just a thought.

  41. Sarah, Three Boys says:

    holy cr– you have no idea how excited I am to have found this today!!!! I am in the middle of doing this, seriously I just finished putting together 5 billy bookcases this afternoon, I have the crown moulding ready to cut, and I found pre-pasted, beadboard, paintable wallpaper at Lowe's for 15$ a roll!! I had no idea it was hard to come by. Ok, question what kind of trim did you use on all of the edges, shelves etc… I was at Lowe's yesterday and couldn't decide, I love yours what is it? I could kiss you!!!! Sarah

  42. Anonymous says:

    HI

    It's a wonderfully well done structure!
    I am trying to do similar thing.
    Your ceiling is higher than mine, so
    my work will be easier than yours.
    My question is

    "Did you fix the case to the
    backing wall? If so, what did you use?
    Or, was enough stability achieved by
    the tight fitting of the case between floor and ceiling?"

    My main concern of this structure is that
    after a while, small movements of the wall/ceiling/floor/book case
    might cause some jarring between the book case and the wall surface ( a cosmetic issue.)

    Thanks.

  43. Anonymous says:

    So inspiring! I'm hoping to do this but since I don't already own the bookcases, I will buy white and then trim it out and only paint the trim. I'll also leave the holes so I can adjust the shelves if needed.

    But this looks great! Could you fill the gap by the wall with caulk or joint compound? (This assumes the bookcase is affixed to the wall, as is usually recommended for safety.) You could use a white flexible caulking so that small shifts in the house do not cause it to crack. You could also apply a very thin piece of narrow trim to the wall, butted up against the edge of the bookcase – something similar to what you used on the front of the bookcase. Thin trim like that (meaning 1/4" thick or something, and maybe an inch wide) is pretty flexible, so you could probably get it to fit the contours of the wall, using plenty of finish nails so that it stays fixed to those contours. The trim would probably be just thick enough (depth-wise) to cover the gap, and since it would be narrow, it would not be extremely obvious on the wall. Likewise, you might apply some quarter-round to the wall at that gap. Fill in any tiny gaps which who with caulk. It looks good now, but that gap would drive me nuts.

  44. I am so glad you were long-winded! I love doing these kinds of DIY projects, but I don't know what I am doing and need every detail!!! Thank you, what a transformation, great job.

  45. furniture stores in los angeles says:

    You really did an awesome job in making the Bookcase. I hardly saw the changes when you painted the bookcase white.

  46. Great job. Have you seen the Ikea Hacker site? If you wanted to get rid of the space you could just put some vertical beading along it. Worth it I reckon.

    1. Marianne@Songbird says:

      Thanks, yes I know Ikea Hacker. You can’t find my Billy Built-in there too.

  47. WOW!!! Beautiful, Creative, Frugal and Functional! You’ve covered it all! While I know it seems like it took forever and was a lot of hard work (and a lot of learning-by-mistake was involved), this project was so worth it! Thanks for sharing your creativity with us!! YOU INSPIRE ME!! Yeah for you!!!

    1. Marianne@Songbird says:

      Thank you! What a nice comment, you made my day.

  48. Karen@itsallgoodhome says:

    Turned out great! I’m considering retro-fitting book shelves for a built in look too to put on either side of my fireplace. Guess I’ll go check out Billy!

  49. You are a brave woman! You did an awesome job. You don’t like the gap on the left but you could put a small piece of white trim against the wall and on the left side of the bookcase. It would fill it in nicely.

  50. Ashleen Moreen says:

    Thanks for that demo!
    It turned out great!
    I am considering myself of doing the same thing also cos I have 3 old bookcase at home!

    Cheers!

    1. Marianne@Songbird says:

      You’re welcome!

  51. What brand of primer did you use?

  52. Sarah Rice says:

    Great job! You handled a lot of issues and it looks fantastic. I had a couple of suggestions that I have used. The beadboard wallpapper: I knocked out one side of my wall creating a shallow pantry that used the 5″ depth of the wall plus 5 more inches beyond the wall for a total of 10″ (enough room for canned goods and boxed cereals). I wanted the same beadboard effect for the inside back. I used a sheet of beadboard paneling. Being only 1/8″ thick it was easy to cut and easy to install. It looks great and is easy to wipe off and clean. For the crack along the wall I would suggest using the spray insulation crack filler “Great Stuff”. After it dries you can cut anything that is beyond the edge. It cuts well. Then I would paint it and glue a very narrow strip of molding. I think that it would look seamless!

    1. Marianne@Songbird says:

      Thank you for your suggestions. Will check them out.

  53. Sabine Meuzelaar says:

    Mooi zeg! En leuke site!! Groetjes

  54. Hi
    I love what you have done to Billy. I am wanting to do the same myself on my 2 Billy’s to go into my chimney breast alcoves and this is what I had in mind (though one is 20cm narrower than the other one).
    I wonder if you cut away the carpet underneath so it could stand on floorboards or kept it sat on the carpet – because I want to fill mine with books/cds and wonder if the weight would pull the coving from the ceiling.
    I plan to paint it all white so I don’t need the wallpaper at the back – you probably won’t notice this if it is filled with books.
    With regard to the gap push a little rolled up paper or cardboard in and run some decorators caulk down the side.
    Thank you for the inspiration x

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