DIY Office Built-in Bookcases -Part Three

DIY Office Built-in Bookcases Series

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

Part Three

Our office built-in bookcases were finally underway thanks to COVID-19 and the Hubster’s indefinite work-from-home orders. Because we were able to raise, stabilize and secure the IKEA Billy Bookcases and complete the frame work to incase the bookcases, it was time to build the window seat bench.

Supplies needed for window seat bench with office built-in bookcases:

  • 3 inch Flat Head Wood Screws
  • 2×4’s
  • Drill
  • Miter Saw
  • L-Brackets

The Bench

The Hubster and I wanted to incorporate the built-in bench feature to complete the symmetry of the office built-in bookcases. In order for the bench to fit and ensure a built-in aesthetic, we measured the space between the two bookcases and cut two 2×4’s to the appropriate length sizes. We had to take into account the actual measurements of the 2×4’s into our total length measurement.

The Hubster and I were both on the same page as far as depth at 18″. It would reflect depth symmetry from the floating concrete desk top on the adjacent wall. To determine the height of the bench seat, we found the standard window seat measurement of 19″.

It’s All About that Base

the bottom bench frame

The Hubster and I had our measurements and we were ready to start building the bench for the office built-in bookcases. But, we encountered a major issue when we first started building the bottom portion of the frame.

Originally, I wanted four cubbies. However, the Hubster pointed out that with four cubbies, the electrical outlet on the back wall would be covered. So the four cubbies thing was shot. Covering up the electrical outlet was not going to be an option. That specific electrical outlet had to be exposed for us to have access to.

If I can’t have four, let’s do three!

And then Mr. Mathematical gave some bad news, again. The Hubster and I couldn’t have three cubbies with equal measurements because the air vent would be cut in half. Which in turn, would mess with the stability of our frame work…Not a good thing! So I made an executive decision because I’m good at that! We would have two long cubbies on the outer parts of the bench and a smaller cubby in the middle. The Hubster just had to do the math, thank goodness he’s good at that! With this amazing solution, the frame work for the bench would be solid, the electrical outlet would be exposed, and the air vent wouldn’t be an issue. BOOM BABY!

Bottom Frame Built

The Hubster and I secured each section of the 2×4’s with 3″ wood screws to build the bottom portion of the frame. Since this portion would be the bottom portion of the bench frame, we cut out the appropriate size of the vent cover we would use. This just made things easier because we wouldn’t have to use the Jigsaw in the house near the hardwood floors.

portion removed for vent cover

The base for the bench was built and it was time to place that bad boy between the two bookcases to ensure a tight fit. Once the bottom frame was placed it was then secured into the wall using 3″ wood screws.

Positioning for Weight

Our next step was to position the inside 2×4’s to support both the 2×4 across length wise and width wise, which in turn would provide optimal strength for seating. The Hubster attached L-shaped brackets on all sides to insure stability.

the window seat bench frame

The top frame was measured, cut with the electrical outlet portion removed, and built. The Hubster and I placed and secured the top portion of the frame onto the about-to-be bench. We secured the top portion of the frame with L-shaped brackets and the wall with 3″ wood screws (shown above).

Insulating the Air Vent Compartment

To ensure that air would flow out of our vent and through the new vent installed in the bottom of the bench we took aluminum foil tape and coated the inside of the compartment. We taped all of the seams to guarantee that air wouldn’t leak out. Given the size of our office, this vent was the only one for the entire room. Because of this we had to ensure the room would receive proper airflow.

Now it was time to install MDF…

But you’ll have to read about that next week, because that process made such a difference. 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 (Currently Reading)
  4. Part 4: Encasing and Painting
  5. Part 5: Floating Concrete Desk


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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