IKEA Built-In Billy Bookcases

Ever since we started amassing a large collection of books a few years ago, I've dreamed of having beautiful floor-to-ceiling bookshelves to house them in. In our last apartment, we had our books stored in bookcases that we nabbed from my childhood bedroom, and they just didn't do them justice. When we found our house back in the spring, we realized our soon-to-be living room had a wall that would be a perfect contender to make this dream a reality.


Last year Sarah showed me a blog post from The Makerista and the built-ins she designed using IKEA Billy bookcases. They were awesome. While Sarah and I like to DIY a lot of stuff, we don't have the tools or time needed to build bookcases from scratch, so using Billy bookcases as a jumping off point is perfect for us. They are customizable with different sizes and colors, they're sturdy, and they're a great price for the quality.


What we thought would be a fairly straightforward project turned out to be an absolutely massive undertaking. It was our intention all along to show you exactly how we built in these bookshelves, so you could do the same, but every step of the way was met with unseen challenges, changes to our plan, and last-minute fixes.

In the final days of the project, we were basically working around the clock, nailing in pieces in the dark at 7 AM, and painting and caulking late into the evenings. We're going to do our best to share our process with you through the photos we have, though the shelves are customized exactly for our space, and are executed using our exact limited resources and tools. There are probably better ways to do a lot of these things, but this was as much a learning opportunity and adventure for us as it was a project. I was literally making it up as I went! (And I had a blast doing it.)

WARNING: This post is about to get incredibly detailed. So detailed in fact, that I won't at all mind if you'd like to just scroll though, enjoy the photos (even the ugly, night time process photos), and pretend like you read the whole thing. If you don't want to know about all of our trials and tribulations throughout this process, don't sweat it, skip it!

Here's what we did:

Our wall measures about 88x96". We needed to make sure that the bookcases were close enough to the ceiling so they could be made to look built in, while keeping them low enough to the floor to make sure that our floor moulding would reach from the floor to the bottom shelf. We figured out that we would need to lift the bookcases off the floor about 2.5".


The first step was removing the old floor trim, and clearing out the space. I then built a simple frame that we set in place and made sure was completely level using some shims (and some folded pieces of notebook paper.) This would become the base on which all the shelves would sit.


We knew that we wanted 3" pine boards to trim the vertical spaces between the shelves, so we measured the bookcases and positioned them far enough apart for the boards to cover the gaps between the three shelves. We then attached them to the wall and the floor base using small L-brackets and screws. Measuring the depth of the shelves, I attached a thin wood strip to the wall flush with the face of the shelves. This would give me a surface into which I could attach the front trim piece closest to the wall. (*Note, when a board says it's "three inches" wide, it's not. Always make sure you take actual measurements of your materials, don't rely on the name of the product! More on this topic later...)


Before we could measure the dimensions for the floor moulding, ceiling trim, and quarter round, we needed to attach the vertical trim pieces. Remember how I said we wanted 3" boards to separate the shelves? And how we attached the shelves at this specific spacing to both the floor base and the wall behind it? Well, 3" finished pine boards are only 2.5" wide in actuality. I assumed I would be able to nail the boards right into the front of the vertical shelf walls, but now I didn't have enough material to safely overlap and drive a nail through! As a fix, I glued up some scrap wood and cut some cleats I could nail in between the shelves from the sides. Once the cleats were in place, I was able to nail the pine boards right into them, and not rely on the vertical shelf pieces. Disaster #1: averted.

With the vertical trim pieces in place, I could measure for the floor moulding, quarter round, and the top trim. After taking the measurements, cutting the pieces to length, and doing several coats of paint, it was time to nail them into place. Except wait! The kick plate of the bookshelves is recessed about an inch and a half (and so is my floor base - my bad), and I have nothing to nail the pieces into. Again, with some overnight glue-ups, and some quick trims on the miter saw, some simple cleats gave me the surface I needed so I could nail in the pieces. Disaster #2: averted.


With the vertical pine boards not quite covering the entire gap between the shelves, I now had a slight reveal I wasn't anticipating. This meant I now had a 1/4" gap between my floor moulding and the bottom shelf. (See where I'm going here? One thing after another...) After cutting to size and gluing some extra thin strips to the top of each floor piece, they were ready to be attached. Disaster #3: averted.


For the outermost wall of the bookshelves, I needed a way to cover the exposed brackets, while creating enough width for the final vertical trim piece to sit flush with the outside edge. I decided to put one large 8' false wall on the outside of the bookshelves and paint it white. Figuring for the depth of false wall, the width of the front trim piece, and the depth of the side trim piece, I was left with a 1/2" gap I needed to fill. I decided to buy a large sheet of plywood that was 1/2" thick and cut some strips to fill the space. Attach the strips, nail in the false wall, trim the front, trim the side, measure for the floor moulding and quarter round, and the outside is done!


We're very close now except for the top trim. The plan all along was to just use quarter round at the top instead of some elaborate crown moulding or something. My tape measure must have been broken on day 1, because the quarter round was nowhere near large enough to cover the gap we had left between the top of the bookshelves and the ceiling. Luckily, I bought a large enough sheet of plywood to use for my spacers on the outside wall that I could just use them as trimming for the top! Disaster #4: averted. That same "reveal" I wasn't prepared to deal with for the floor moulding was also a factor at the top. This time, however, since my new trim was deep enough, I could just use some chisels to carve out the corners so the pieces could sit flush between the pine boards and against the face of the shelves. (There are no pictures of this step, as I had completely lost my mind by this point.)

Then it was on to a TON of caulking (because I'm still pretty new at all of this and there were a lot of gaps to be filled), filling nail holes, and a final coat of paint on everything, and we were done!

That's it! It's that simple (?!), and even you can make up a project step-by-step as you go!


In all seriousness, I'm extremely proud of how these turned out, and I love the way we have them styled. Finally, floor to ceiling built-in bookshelves are a reality in our home, and I couldn't be happier with them.

Sarah & Nick