Skip to Content

How to Make a DIY Wall-to-Wall Ikea Built in Bookcase (A Billy Bookshelf Hack)

Sharing is caring!

We may earn a commission on purchases made after clicking links on this page.

Intro by Robin
Steps by Ed

basement guest room library before

A small basement bedroom is tricky.  When that bedroom is in an equally small basement that needs to function for a lot of things – it requires some creativity and mad DIY skillz.

Enter our Basement Guest Room-Library with wall to wall bookshelves.  I’ve dreamed of having built-in bookcases my whole life! (Is that a normal dream?)

Now, of course, if we didn’t want to make our guest room beautiful as well as functional, we could have just pushed some premade bookshelves up against the wall and called it a day.

But, as you may know, that just isn’t our style.  We demand function AND beauty.  PLUS we love the challenge of creating rooms on a budget.  That’s what all our DIYs are about.  (Have you seen the closet we turned into a basement bathroom? We’re still gaga for it.)

This basement guest room needs to work really hard for us:

  • It must make our guests feel comfortable and loved.
  • It needs to hold the bulk of our book collection (our house isn’t huge and we LOVE books)
  • It also must have hidden storage for less than beautiful things (I’m thinking bedding, gift wrap storage and files.)
  • And it needs to look great. (And it does! Despite what my beginner photography skills show…sigh.)

And yet another problem to solve…

basement window before guest room

This IKEA Billy Bookcase Built-in is a problem solver. 

Like most basements, ours has small windows. The one in the guest room is weird and it isn’t centred.  This made me bonkers! (Though we figured out a clever way to make it look bigger!)

The only comfortable spot for the bed was under this window.  With the window off to one side – the bed wasn’t centred.  (It made me twitchy just looking at it.)

That’s one of the reasons this bookcase built-in was so perfect down here.  By building it along the left wall it took up enough of the visual space to make the weird window look a bit more centred.  Win!

Another reason this built-in bookcase was a win is the character and personality that it adds. 

You know from the other built-ins we’ve made that we are Co-Presidents of the Built-ins Fan Club.  Seriously, built-ins are amazing small space solutions – and they aren’t as hard to build as you may fear.

Last fall IKEA had the sale I was waiting for: 30% off all their Billy bookcases and matching Oxberg doors

The bookcases are already pretty affordable, especially in white.  The Oxberg doors were more costly – a pair of the door’s cost as much as the whole bookshelf!  But I knew that we needed the doors for the hidden storage they’d give us.

So I added it all to my cart and paid to have them shipped. 

That was a tough extra cost to pay – but these Billy bookcases are dang heavy!  And we didn’t think we could fit 3 Billy’s plus 6 doors in our Rav4.  There are times that delivery is worth splurging for.

Without further ado, here’s how to make a wall-to-wall bookcase with our IKEA Billy Bookcase Built-in tutorial.  (And we added bookcase lighting to them too, so pretty!)

how to diy a simple ikea bookcase built in

How to Make a DIY Wall-to-Wall IKEA Built in Bookcase (A Billy Bookcase Hack!)

What you need:

  • As many flat-pack bookcases as will fill your wall.
    • IKEA Billy’s are great – but it’s not the only option, you can find similar bookcases at
    • Amazon (like this one),
    • Lowes (like this one) and
    • Home Depot (like this one) for example.  Comparison shop!
  • Bookcase doors – we used Oxbergs
  • 2x4s
  • sandpaper and sander (we use this random orbital one)
  • clamps
  • screws
  • paint – We found Behr’s “White” in eggshell matched the IKEA finish really well.
  • MDF trim, casing and crown moulding, as needed

Optional: How to Add Faux Brick to the Back of a Built-in Bookcase

This is totally optional – gilding the lily really – but we love the look.  You can find how we did this interesting step in the tutorial here.

Optional: How to Add Bookcase Lighting to Any Bookshelf (without hiring an electrician)

We added these super affordable picture lights from Home Depot to our bookcase (Amazon has them, too).  Rather than create one post with 4000 photos, we broke it down. 

Here’s the tutorial – we include 4 ways to add lighting – and 3 of them don’t require ANY electrical skills!

If video tutorials are more your style – just press play here:

How to make a Billy Bookcase Built-in:

Step 1: Assemble the BILLY bookcases.

ikea built in bookcase install upside down

If you want to add the character of the faux brick, this is the post to help you to do that.  Here’s the tutorial.  Otherwise, use the existing backs that come with the bookcases.

  • So, you may wonder, why the heck did we install these upside-down?!?  
    • A fair question.  This room is not tall – about 6.5 ft.  But we knew we wanted to add library lights to the top of each shelf.
    • By installing them upside down we had room for lights and crown moulding!
    • The uniform nature of the BILLY meant that we could do this – have the doors still fit on the bottom half.

Step 2: Decide on the spacing

ikea built in bookcase decide on spacing
The easy one to decide on was the centre bookshelf – we centred it. Then we played around with spacing the other two shelves until it felt right.

We ended up using 2×4 stock as the gap between units to make them look a little more substantial.  We set them back by about 3/8″.  (And 2×4’s are super cheap!  They just need sanding like crazy.)

Step 3: Clamp and Commit

ikea built in bookcase spacing with 2x4 and clamps
This means screwing into the bookcase units and mounting to the wall.

IKEA provides brackets to attach to studs to prevent tipping over: use them.

Even though you’ll be putting lots of framing around it, the brackets will help hold things in place, and keep them square, while you build everything else.
ikea built in bookcase anchor center one
IKEA provides lots of these brackets – we used them to connect to not only studs but joists and anything else we could find.
ikea built in bookcases clap and screw spacer
Clamps are your friend. Once you have the BILLY units assembled, connected to each other and secured to the wall, they can be removed.

Step 4: Screw the bookcases to each other

ikea built in bookshelves hide screws at top
When joining the bookcases together, try to hide the screws whenever possible in places you won’t see. 

These ones will be hidden by the crown moulding
hot to hid the screws in ikea bookcase

And if you have doors, the hinges can be used to hide screws too.

Locate where the hinges will land and then use one of the predrilled holes that will be behind the hinge.
ikea built in bookcase attach door hinges
Tadaa! Hidden screw. You can attach the doors at this point too (if you’re adding them). We had to move up the hinge mounts a tiny bit to make the door tops level with the middle shelf.

This was really just an aesthetic issue – not a functional one.

Step 5 – Fill in next to the walls

ikea built in bookcase end cap to match center space
We made a choice to have a larger space between the sides of the bookcases and the wall.This looked better than 4 exactly even gaps.
Side Question: Does anyone else begin styling their projects for ‘After’ photos while they are still in the middle of construction? Asking for a friend…
ikea built in bookcase bracing side to end wall
We built small frames and then attached some primed MDF casing to hide the gaps and make the whole unit look like one complete piece.

Give yourself lots of room to nail into. Primed MDF will give a nice, finished look – consistent with the rest of the BILLY unit – but they are not very rigid and need support.
ikea built in bookcase cover end wall bracing

The MDF may need some trimming and sanding to fit in next to the wall. (Unless by some miracle your walls are perfectly square.) 

Keep trying it in place till it works. 

Step 6: Crown Mould and remaining finish trim

ikea built in bookcase finishing top crown moulding
We added bookcase lighting (tutorial is here), but the rest of the trim would be similar – only MUCH EASIER for you if you didn’t incorporate lights. 

First, over where the kick plates would be, we added a thin piece of pre-finished MDF panel.
Then we added crown moulding at the ceiling.
ikea built in bookcase finish trim for gap

Last, we cut another strip of 3/8, thicker MDF to make up the remaining gap.

Step 7: Fill and Sand, Caulk and Paint

ikea built in bookcase caulk on top trim
You can hide all kinds of messes with painted projects!  

Fill those gaps with caulk and holes with wood fill. 

Sand it smooth and paint.

And then you’re done!

built in bookcase billy hack IKEA

We are bookworms, so filling these shelves with books was easy.  And we all love the look of a well-loved library.

You might have noticed that we didn’t put any hardware on the doors – that’s intentional – though we may change our minds when the final room comes together.  We left it without pulls because the room is tight and we wanted to keep the area beside the bed as open as possible.  This way our guests aren’t snagging their jammies on any knobs when walking by the shelves to climb into bed.

wall to wall bookshelves IKEA billy diy

Other projects in our Basement Guest Room-Library:

Simple DIY Built-ins are out spreciality, here’s a few of ours…

Sharing is caring!

Michel Romage

Thursday 10th of June 2021

This is a great and beautiful project. One of the best I've seen. I will definitely be building this unit in my home office.


Thursday 10th of June 2021

Thanks so much, Michel! Let us know how your project goes! :)


Tuesday 17th of November 2020

Love your ideas. You guys are really clever.


Tuesday 17th of November 2020

Thanks so much, Ellen! So glad you like our work! :)


Thursday 17th of September 2020

I love this tutorial! Where did you get the lights? Pretty! Thank you!


Friday 18th of September 2020

I'm glad you like it! Here's a source for the lights: :)


Wednesday 12th of August 2020

Could I do doors on the top half also? Would 4 doors fit?


Thursday 13th of August 2020

Hi Rachel! Yes! The oxberg doors are designed to fit on both top and bottom if you want. :)


Monday 9th of March 2020

I really like all of your projects. For this one I would probably use wood boards for the shelves as MDF has a tendency to bow from the weight of books (and anything else!). I would also slide the shelves forward until they're flush with the front of the bookcase to allow the cabinet doors to close straight without leaning inward against the edge of the inner shelf.