DIY Office Built-in Bookcases-Part Four

DIY Office Built-in Bookcases Series

  1. Part 1 : Planning
  2. Part 2: Framing
  3. Part 3: Built-in Bench
  4. Part 4: Encasing and Painting (Currently Reading)
  5. Part 5: Floating Concrete Desk

Part Four

Our office built-in bookcases were almost complete! Thanks to COVID-19 and the Hubster’s indefinite work-from-home orders the only thing stopping this office built-in bookcases from being completed were in the details. The Hubster and I still needed the bookcases to be encased with MDF, nail holes and seams to be filled with wood filler, everything sanded, and then painted.

Supplies needed for office built-in bookcases:

It was (finally) time to make them pretty!

To make the bookcases achieve the desired built-in aesthetics that the Hubster and I were desiring, we knew that we would encase the bookcases, framework, and bench in MDF. The Hubster and I ended up using six MDF boards for this project. We found that the easiest way to cut the MDF was with our Jigsaw using a wood cutting blade.

the hubster cutting the MDF

In order to achieve as straight as line as possible, we would mark the desired measurements and then connect the measurements markings using a 2×4 as our ruler. Although the Hubster tried, his cuts weren’t always as straight as needed. So word of advice: use the outside of the MDF boards on places where straight cuts are extremely necessary.

The MDF was then attached using our air compressed finishing nailer with 2″ finishing nails.

Encasing the framework and bookcases in MDF took the better part of two days. Before we could encase the area around the desk, we needed to make and install the floating concrete desk. It was quite the process that you’ll want to read about, next week.

At that point, the bookcases were actually resembling built-in bookcases.

Sand On, Sand Off

I sanded everything first before wood filling any imperfections and joint seams. This made it so that I could only fill what was absolutely needed. To do this, I used a 40 grit sanding pad on my HART orbital sander to ensure the most efficient result. In order to make the MDF boards that encased the bookcases that were slightly crooked, I placed my sander flush to the bookcase to insure a straighter result.

Once everything was sanded, it was time to cover up nail holes, imperfections and joint seams with wood filler and a putty knife. This process took quite a bit of time so patience is really the key here. You’ll want to make sure that the wood filler on any imperfections is smooth and make it as flush as possible to the MDF boards. This will allow you to save time when sanding again and will make it so that there is an even finish to the built-ins.

Once the wood filler has dried, you’ll want to sand the bookcases again. Using a 40 grit sanding pad and orbital sander, you’ll make sure there is a smooth and even finish to the built-ins.

sanding the built-ins while covered in sawdust

Clean, clean, clean

I wish I would’ve know how much of a mess sanding, wood filling, and sanding again would make. You’ll want to make sure to really clean the built-ins before painting them with chalk paint. Had I known now what I wish I would’ve known then, I would have removed the extra shelves before I sanded the first time. Trust me on this! It’s one less thing you’ll have to clean.

Add the Finishing Touch

By this point, you’ll want to add the crown molding to the built-ins to complete the built-in aesthetics. We attached the crown molding using our air compressed finishing nailer with 2″ finishing nails. If you have any corners where your built-ins meet, you’ll want to practice a few of your cuts on an extra piece of molding because it’s quite tricky to get right.

crown molding installed

Once the crown molding is attached, you will reattach the baseboards. Due to the angles and length of our built-in bookcases, we could not reuse our original baseboards. We couldn’t purchase new baseboards either! The baseboard design our builder used only came in 3 1/4″ baseboards from our local home improvement store. However, our original baseboards were 3 1/2″.. So it was either replace the baseboards in that room or have a 1/4″ difference in height. You bet we bought new ones…

You’ll want to fill in nail holes on the crown molding and baseboards with dry wall spackle using a putty knife. Next, you’ll caulk the edges of the bookcases and baseboards so that there will be a clean line where they meet the walls.

Chalk it Up

Using painter’s tape, you will tape off the walls so that you can prepare to paint. Using chalk paint and a foam brush roller and paint tray, you’ll began to paint the built-in bookcases. You’ll want to apply two coats of chalk paint to the built-ins. This will ensure that the MDF will not soak up an insane amount of interior paint and will make it so that the interior paint will adhere to the IKEA Billy Bookcases. I used Annie Sloan Chalk Paint in the color Navy to ensure a rich dark base color for our built-in bookcases, once I decided on the color of course.

Make it Blue

I was really debating on what color we should make the built-in bookcases. Do I play it safe with a white? Do I do a traditional black? Should we do a bold color?

While debating this for a few days, I was ultimately leaning towards a bold color. It is the Hubster’s office and he one of color. I still remember when we were Newlywed’s in Bed, Bath & Beyond debating over shower curtains because I was playing it too safe with a white and black shower curtain. So I felt that going with a bold color would be a good choice for him, but it needed to have a masculine vibe.

Navy felt like it would be a great choice! But then it was trying different paint samples and I just wasn’t feeling any of them. After talking to the Hubster about it before bed, he said “Paint it the color of our Master Bathroom”… I went with it! And Gentlemen’s Gray by Benjamin Moore was the color for our built-in cabinetry.

I wanted to ensure that the built-in bookcases would look aesthetically custom. However, using a paint sprayer was out of the question because the Hubster had to be able to work in the office while renovations occurred. So I used a Purdy Ultra Smooth brush roller to ensure a smooth finish to mimic sprayed cabinetry.

Seal it Up!

To ensure durability, I applied the General Finishes High Performance Top Coat in a satin sheen. I used a foam brush roller and paint tray with two very thin coats. You’ll want to make sure that you allow the built-ins and shelves to cure. The more time you allow, the better.

….and Decorate!

The great thing about decorating is all of the finishing details, one of which is a no-sew bench seat cover. Don’t worry! I’ve got your back and that will be posted shortly. Since we are always working on new things at the Farmhouse, I like to share snippets of these projects and other parts of my everyday life craziness on my Instagram account. Come stop by!

DIY Office Built-in Bookcases Series

  1. Part 1 : Planning
  2. Part 2: Framing
  3. Part 3: Built-in Bench
  4. Part 4: Encasing and Painting (Currently Reading)
  5. Part 5: Floating Concrete Desk


big thank you to HART tools for providing the orbital sander mentioned throughout this post. The power tools listed above are dangerous and if not used properly can result in fatal injures or death. If you are not comfortable using these power tools please consult someone who does.

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