Window Seat Reveal: DIY Window Seat From A Set of Thrifted Bookcases

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In this post, I’ll share exactly how I created a DIY window seat in my daughters bedroom using a thrifted set of bookcases/file cabinets. Using and repurposing thrifted furniture is a great way to keep costs affordable, it’s sustainable, and it also helps save time! A win win in my book for sure!

Starting a bedroom makeover with DIY window seats

The very first thing I wanted to tackle in my daughters room was a window seat. I wanted to build these to resemble built-ins. Not only would it be a beautiful feature in her room but it would also increase storage and function in the space dramatically!

The plan was to use pre-fabricated cabinets on the side and build a bookcase on top from scratch. That is, until I stumbled across a set of identical bookcases/file cabinets. The pieces were in excellent shape, the drawers were on sliders and worked well an everything about it just felt like fate.

I got them home and they fit PERFECTLY in the spaces next to the window and my heart did a little dance. This was going to save so much time, money, and material!

Extending the bookcases with cabinets to add height and storage

After getting them home, I realize they did need to be a little taller to fit my vision. I wanted to completely build these in so the bookcases needed to be a little taller than the height of the window.

Since using pre-fabricated cabinets was part of the original plan, it gave me the idea to add them to this piece of furniture. It would add height, and allow my daughter to have another place to store her items. Hidden storage is always a win in my book!

Above is how it looked once I set the pre-fabricated cabinets in place. I wanted to visualize them in place. It was perfect for my plan!

I’d build the window seat between the two units and then bring it all together to be one cohesive piece.

It is 100% possible to marry thrifted furniture, pre-fabricated cabinets, and a built-from-scratch piece to all come together as one. I like to think it’s my super power!

Stick around until the end to see how it came out ;-)

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Removing the carpet and building the built-in base

The first step was to remove the carpet and add a new tack strip in.

There are a few reasons you’ll want to remove the carpet for built-ins:

  • Carpet will settle over time and as it does, your built-ins will no longer be level. This can create a lot of issues especially if drawers are part of your piece of furniture
  • If you ever want to have your carpet removed or replaced, this can become a huge pain!

I used my electric power cutter to cut and remove the carpet. This was infinitely easier than a box cutter and I was also able to get a super straight line. This thing comes in handy for everything from hard plastic packaging to cutting down cardboard – I can’t live without it! (I used my Hart power cutter for this, but also have this more affordable one here)

After the carpet is removed, you’ll also remove the padding and the tack strips from the area.

Then, install a new tack strip. This is very easy to do, they come with nails that you’ll just tap into your subfloor, then you’ll re-stretch the carpet and the tack strips will keep it in place. Done!

Time to build the bases for the cabinets! Bases will help ensure that you’re cabinets are level and properly supported.

These are very simple to create: you’ll just make a box with some 2x4s and attach it to the studs in your wall. Shims can be used to ensure that they’re level with the subfloor.

Installing the thrifted cabinets

The next step was to install the thrifted cabinets onto the bases. I removed the trim that was on the original furniture piece and detached the bookcase from the cabinet portion. Then, I attached those to the stud with L-brackets.

Afterwards, I attached the prefabricated cabinets and drilled those directly into the studs and positioned the bookcase on top of those. Which — you guessed it — was drilled into the studs as well! It was really important to me that this is solid!

This is what it looked like once the sides were fully installed.

Building the window seat

Now that the sides were in place, I could build the window seat. To do this I used 2x4s to frame out the window seat.

I also needed to extend the vent to the front of the window seat which I accomplished with a flexible duct (since it needed to be moved over to be centered) and a register elbow. You can see the materials I used for this here.

I secured it all together with foil duct tape and duct clamps. I tested it out to make sure it was completely air tight and working properly.

Disclaimer: I am not an HVAC specialist, you can simply order a toe kick duct extension kit off amazon or call a HVAC specialist if you’re not comfortable DIYing it.

Once that was in place, I finished up the frame and covered the frame with MDF and scrap plywood both on the inside and on the outside. I opted not to move our outlet forward because there are already 5 other outlets in the room and I thought it would be an eye sore on the front of the seat.

I used a couple of poplar boards to create a top for the bench and attached it with a piano hinge so we could open it up for even more stroage!

Finally, I added some trim details to the seat and it was time to finish this up with the header. Building in the top is what will really make this look like an actual “built-in” and really bring the vision home!!

Building in the header of the window seat

To accomplish this, I built a simple frame with 2x4s which I screwed into the top portion of the bookcases. Then, I covered that frame with leftover drywall that I had from the playroom project.

I attached 1x8s all the way across the top and attached a decorative crown molding.

Adding arch details to the bookcases

Before being ready to paint, there was one final detail that I wanted to add!


I used my router and a circle jig to cut out the arches. Alternatively, you can use a jigsaw to cut out arches, but I didn’t trust myself to get a smooth enough line so I went with the router — I wanted them to be absolutely perfect!

After installing some beadboard in the back of the bookcase, I attached the arches with wood glue and nails.

Finally, it was starting to look like something!!

Priming and painting the built-in window seat

Prepping for paint is tedious but necessary! The first thing I did was wood fill, caulk, and sand. This is an important step that will make a big difference in the finish of your project!

I primed all of the MDF using a shellac based primer as well as all of the wood that contained knots. This is recommended because a water based primer can make MDF swell. Shellac based primer will also seal any knots and prevent bleed-through with your paint.

While it is more expensive, I didn’t want to go through all this work just to see knots in my paint!

If you’re new to my page, I often use whatever material I have on hand first. I collect a lot of scraps from projects and my dad gives me some from job sites as well. This can cause a little extra work because the material is not all the same, however it saves a ton of money and is so much better for the environment not to end up in a landfill!

To save my shellac based primer, I used cheaper water based primer on the bookcases and cabinets. Then, it was time to paint!

My favorite paint is the scuff defense line from Behr. I used the color Aged Beige and it just might be my favorite beige ever.

Final touches for the window seat

I decided to go the custom cushion route because I needed something that would be easy to clean. I wanted to be able to remove the cover and wash it. Typically, DIY cushions are made by attaching foam to plywood, then covering it with fabric and stapling it to the wood.

While I might do this if it was my bedroom, I just don’t trust my daughter enough to keep that clean! I ordered from Patio Lane.

I also installed new hardware for the drawers and sconces.

For the sconces, I used this set of two from amazon and used magic bulbs instead of hardwiring them. They work great and really add both style and function to the built-ins!

Are you ready to see the final look?

Here’s what the space looked like before:

Here’s the final look:

Interested in this build and want to learn more?

This entire project is saved, step by step, to my instagram highlights (“window seat” and “window seat 2“) — you can watch the whole build there!

Up next for the bedroom makeover, I will be tackling the walls! Be sure to follow along in real time on Instagram and subscribe to my Insiders list so you don’t miss a thing!

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