DIY IKEA Bookshelf That Looks Built-In

This DIY IKEA hack uses the IKEA Billy bookcases to make bookshelves that looks like a professional built-in bookshelf.

You may have seen our post about how we organize our homeschool room, and that includes using IKEA bookshelves that we converted to make them look built-in!

This is going to be different for each room because of dimensions, obviously. We also made sure to have an inch or so in between bookcases so we could give them the built-in look.

It was actually pretty simple. We used the Billy IKEA bookcases, along with the Billy height extensions to get shelves that went from wall to wall and floor to ceiling.

Phillip installed build the shelves and anchored them to the walls with about 3 inches of space in between each.  He then purchased wood to fill in the gaps and caulked and painted it so it would have a finished, built-in look. 

Before we put the bookshelves against the wall, we removed the baseboards along that wall. Then once the bookshelves were built, we put the baseboard along the bottom of the shelves for a more finished look.

If you also have crown molding in the room you’re building your IKEA bookcases, you can remove that as well, then add it back on.

Use the step-by-step guide below to help create your built-in IKEA bookcase, and also check out these other DIY IKEA hacks.

Creating a Built-in Look with IKEA Billy Bookcases: A Step-by-Step Guide

IKEA’s Billy bookshelves are renowned for their functionality and affordability. While they can be a great standalone storage solution, with a few simple steps, you can transform them into beautiful built-in bookshelves that seamlessly integrate with your space.

In this step-by-step guide, we will explore how to make your IKEA Billy bookshelves look like custom built-ins, adding a touch of elegance and sophistication to your home.

Step 1: Measure and Plan

Before you begin the assembly process, it’s crucial to measure your space and plan the layout of your built-in bookshelves. Take accurate measurements of the area where you intend to install the Billy bookshelves, considering the height, width, and depth of the available space.

Additionally, consider any architectural features, such as windows, doors, or electrical outlets, that may impact the placement and design of your built-ins. With these measurements in hand, you can determine the number of Billy bookshelves you will need and how they will fit within the designated space.

Step 2: Purchase and Assemble the Billy Bookshelves

Visit your nearest IKEA store or explore their online catalog to purchase the Billy bookshelves in the desired size and finish. Keep in mind that you can choose from various heights, widths, and depths to suit your specific needs.

Once you have your Billy bookshelves, follow the provided assembly instructions to put them together. Take your time to ensure each shelf is sturdy and securely assembled, as this will form the foundation for achieving the built-in look.

Step 3: Secure the Bookshelves to the Wall

To create a seamless and secure built-in appearance, it’s important to attach the Billy bookshelves to the wall. Use wall anchors or screws to secure the bookshelves at the top, bottom, and back panels.

This step will not only ensure stability but also prevent any accidental tipping or movement.

Step 4: Fill in Gaps

One of the key aspects of achieving a built-in look is to eliminate any visible gaps or spaces between the bookshelves and the surrounding walls. To accomplish this, you can use a combination of trim molding, caulk, and paint to create a seamless and cohesive appearance.

Measure the gaps between the bookshelves and the walls, and cut trim molding to fit those spaces. Attach the molding to the bookshelves and walls using finishing nails or adhesive. Fill in any remaining gaps or seams with caulk, and smooth it out for a clean finish.

Finally, paint the molding and caulk to match the color of your bookshelves and walls, ensuring a unified and integrated look.

Step 5: Add Crown Molding

To elevate the built-in aesthetic and give your bookshelves a polished look, consider adding crown molding along the top edge.

Measure the length of the bookshelves, and cut the crown molding to fit. Attach the crown molding to the top of the bookshelves using finishing nails or adhesive, ensuring a secure and seamless connection.

Paint or stain the crown molding to match the color of your bookshelves and trim, creating a unified appearance.

Step 6: Customize the Interior

One of the advantages of IKEA Billy bookshelves is their adjustable shelves. Take advantage of this feature to customize the interior of your built-ins according to your storage needs.

Arrange the shelves at different heights to accommodate books, decor items, or other belongings. Consider adding additional accessories, such as drawer inserts or doors, to further personalize the look and functionality of your built-in bookshelves.

Step 7: Style and Decorate

With your newly created built-in bookshelves, it’s time to add your personal touch and bring them to life. Arrange your books, decorative objects, and keepsakes on the shelves, creating a visually pleasing display.

Play with different heights, colors, and textures to create a balanced and visually appealing arrangement.

Consider incorporating lighting elements, such as LED strip lights or spotlights, to highlight specific items or add a warm ambiance to the shelves.


Transforming your IKEA Billy bookshelves into beautiful built-in units is a rewarding and cost-effective way to elevate the style and functionality of your space.

By following these step-by-step instructions, you can create custom-looking bookshelves that seamlessly blend with your home’s aesthetic.

Remember to measure carefully, assemble securely, fill in gaps, add crown molding, customize the interior, and finally, style and decorate your built-ins to make them a stunning focal point in your room.

Enjoy the process of creating a unique and personalized storage solution that will enhance both the organization and aesthetics of your space.

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