How to Turn Store-Bought Bookcases into Custom Built-ins

Monday, December 14, 2020

I've been planning to write up a post with more detail about the Home Office built-ins' trim work even before the One Room Challenge ended.  I think many of us are visual learners, so hopefully having the trims listed out will help if you want to do a similar project.  I started with Target bookcases, but I think the premise can be applied to any basic bookcase.  And feel free to use these trims as a jumping off point.  There are so many different options, so mix and match to cover seams and create a look that you like!

These bookcases were previously standalone bookcases from Target, that I added an additional unit to, to the raise the height.

After vertical shiplap was added to the wall, the upper and lower units were secured to the wall.  I also secured them to each other using 2 1/2" trim screws.

Then I added lots of trim to create a seamless, built-in look.

The pictures below show the exact trims I used for upper and lower sections of the bookcases, and trims used cover the seams where the all the individual bookcases met.

All of my trims were attached with my Ryobi brad nailer and then caulked and painted. I don't generally use glue when I add trim. That way if I need to adjust or remove, it's easier to take apart. To see the full finished office, click here.  If you tackle a similar project, tag me on Instagram @oakhousedesignco! I would love to see your work!


  1. Replies
    1. These are so beautiful! Do you know where you got the lights from? I love them!

  2. I have been in the high end residential design and construction business for over 30 years. I stumbled across your site when looking at hood ideas for a project and I have to say I am blown away by your creativity in coming up with solutions that are budget friendly and could be applied by almost any homeowner. The way you updated your house without tearing the whole thing apart and rebuilding is very impressive! When do get YOUR HGTV show?? :)

  3. Hi - can you tell me/us more information about the doors on these shelves? I love this look and the details you've given, but am still fuzzy on the details about the doors. Thank you!

  4. This built-in bookcase is GORGEOUS! Great job!

  5. This is amazing! Thank you for such detailed instructions. Did I miss where you shared about the cabinet doors? Were they part of the original bookshelves?

  6. This is great! Thank you for the clear directions.

  7. I have these exact bookshelves and have been scouring the internet for a built-in look for my schoolroom. Thank you for posting!