How to Build Floor-To-Ceiling Bookshelves (With a Window Seat)

Learn how to make built-in bookshelves with a window seat and cabinets. The tutorial is simple-to-follow, and the bookshelves turn out beautiful.   

Ever since building my first bookshelf in our first home, I’ve had a hankering ever since to do another one but on a much more grand scale.

My wish came true when Eileen came to me one day with some ideas for her office in our new home. An exciting project was brewing!

Since we didn’t have any large bookshelves in our present home, most of the books we packed up during our move were still in boxes. I’m talking cartons and cartons of books.

They were taking up a lot of valuable space in various locations around the house. So bookshelves were sorely needed.

Initially, we were leaning towards a large L-shaped bookshelf in the office. Then Eileen had a great idea of placing the bookshelf against the window wall and incorporating a window seat.

The office window wall was very bland and not very exciting to look at. It was almost begging for a renovation.

Although it would provide a little less shelf storage than our initial L-shaped shelf idea, it would still be more than enough for all our books.

Also, the window seat would provide a little extra underneath cabinet storage, which is a pretty cool feature.

This room is a little sitting room off of our bedroom.

We originally felt like we would have no need for this room, but after staying empty for a few months, Eileen moved her office/craft room in here.

Update: We actually did something pretty cool with the L-shaped space that we didn’t use for this built-in bookshelf project. We made a craft corner using pegboard, wall-mounted cubby shelves, and simple shelves.

Later on, we added swing-out shelves, which is perfect paint storage.

Planning the Built-In Bookshelves with a Window Seat

The project was essentially going to be two separate built-in bookshelves (on each side of the window) with a seat connecting the two in the middle. The seat would be sitting atop some wide kitchen cabinets for extra storage.

Above the window was just enough space for a single small shelf to store decorative items or horizontal books.

Even though it would be a small shelf, Eileen felt that it would add a lot aesthetically, and there are always creative ways to decorate.

Finally, some baseboard would run along the bottom and some crown molding at the top.

Some designs I saw online used a standard shelf depth (around 12”) with the seat extending out further.

Eileen didn’t want a protruding edge, and she has an eye for design.

So to prevent this, the depth of the seat had to be the same as the bookshelves.

Due to a closet opening on a perpendicular wall, I was restricted to a maximum depth of 15.”

I was a little worried that this would not be enough depth to sit comfortably on, but a few trial sittings on 15” planks of wood proved to be acceptable.

This also meant deeper than normal shelves, but I wasn’t too concerned. I’m sure any extra space behind some books could be put to good use.

As with most of my projects, I started off in TinkerCad to sketch out a 3D design of what was floating around in my head.  I came up with the following:

Determining Materials

With the design for built-in bookshelves flushed out, I was ready to begin.

I strongly considered using melamine-covered particle board for the shelves, but instead opted for some good quality birch plywood.

Although the birch was a little more expensive, I wasn’t comfortable embarking on a project this size using melamine –  a material I have never really worked with before.

Also, I wanted to use stronger material than melamine-covered particleboard.

Next, I used a drawing program on my computer (Photoshop) to calculate the minimum number of 4 x 8 sheets of plywood needed to cut out all the required bookshelf pieces.

I then placed a Home Depot delivery order for all the bookshelf lumber (including some 2 x 4s and 2 x 6s for various segments in the design, baseboard, and crown molding for the trim and some miscellaneous hardware).

Ordering from the home improvement stores is so convenient, but you do have to be careful because you aren’t the one picking out your wood. Still, I do like to order this way for convenience.

Here is the diagram I made in Photoshop to calculate the number of 4 x 8 plywood sheets needed:

Constructing The Built-In Bookshelves

After I got the built-in bookshelf wood, I quickly cut the plywood sheets into 15” wide strips using my circular saw and stored them for use shortly. This helps me to prepare for the project.

With all the materials on hand, I embarked on building these bookcases with a window seat.

Removing Carpeting

The first step was to remove the carpeting where the bookshelf would rest.

For a flat platform to build on, it needed to sit directly on the floor plywood sheathing. I accomplished this with the help of my utility knife and a metal ruler to help guide the cuts.

Then I removed some existing baseboard trim so the bookshelf could sit flush against the wall.

The use of my oscillating multi-tool helped out here to remove just enough baseboard, leaving the rest intact, so that the bookshelf would seamlessly blend in.

Here’s a picture showing me making progress on prepping the floor.

I had to be extra careful removing the carpet tacking strips at the edges, as they were riddled with rusty looking nails:

Building The Foundation

Once all the bare plywood flooring was exposed and the baseboard removed, I started work on the foundation for the two end bookshelf segments.

They would rest directly on the bare floor. I assembled the frames from 2 x 6 wood.

​Here’s a picture of the completed frames:

While constructing the frames in the garage, the corners needed to be very square.

I didn’t have a 90-degree clamp at the time to assist, so using a scrap piece of 2 x 4 and two handy bar clamps, I got creative.

​As seen in the picture below, I was able to lock in place two perpendicular pieces of wood allowing me to fasten them accurately with screws:

Here’s a picture of one of the frames in position resting on the bare floor (notice how I carved some grooves underneath to allow a coaxial cable to run through):

RELOCATING THE AIR VENT

I left the middle foundation frame (that the seat would rest on) for last as it would be a little trickier than the others.

There was a central air vent on the floor where this middle frame was going to sit, and so I had to redirect the airflow.

After brainstorming various ideas for accomplishing this task,

I settled on a very simple yet effective method. I was just going to build a wooden duct into the foundation frame, and seal the inside edges with caulk to make it air-tight.

Here is a picture of the end result (a louvered vent would be inserted into the front hole, which I cut out with my trusty jigsaw):

Here’s a picture after I caulked the wooden duct:

Securing The Foundation Frames To The Wall

Once the foundation frames were complete, I secured them in place. I used some lag bolts to attach the rear of the frames to some wall studs.

Then I used some L brackets to secure the front to the plywood flooring.

Here is a picture showing some L brackets in action:

You might have noticed a number of pocket holes in my construction.  They are very convenient for attaching wood perpendicular to another one, especially in tight or not easily accessible areas.

With the help of a jig (I use the Kreg Pocket Hole Jig), they are very easy to make.

​Here is a picture of one of the pocket holes up close:

Helpful Tip: Here’s a useful trick I used while making the foundation frames.

I had made a few alignment errors on the first frame, so I had to unscrew a few pieces and adjust.

Some wooden toothpicks came in very handy to plug the existing screw holes so that I could re-screw very near to those holes.

​I simply stuck the toothpicks in the holes and broke off the protruding pieces.  Here’s a picture of me ‘toothpicking’ the holes (all we had were party toothpicks, hence the bright colors):

Constructing The Shelves

With the foundation frames in place, I decided to start work on the shelves. It was getting exciting!

MAKING DADO GROOVES

I used the same technique as the first bookshelf I built in our old home – dado grooves to support the shelves, cut with a standard plunge router.

To start, I placed 2 of the bookshelf vertical end supports side by side, clamped them together tightly, and marked with a pencil where all the dados were to be cut.

Then using some scrap wood, I built a simple jig for my router to speed up the cutting and make all the dados identical.

Here are some pictures showing the jig and the router in action.

With the help of the jig, cutting the dados was pretty effortless. Eileen even lent me a hand and cut some of them for me, while I did some other tasks.

​Here are what the dados look like after routing:

ATTACHING THE INDIVIDUAL SHELVES

After the dados were all cut, I started attaching the individual shelves. To do this, I first applied some construction adhesive to the side of a shelf.

Then I inserted it into one of the dado grooves.

Then while using some right-angled clamps to hold the shelf in place (I decided to buy some to assist with this project), I fastened 3 deck screws from the other side to complete the task.

Here is a picture showing a shelf being attached:

Only the inner shelves used dado grooves.  The top and bottom shelves were attached with just adhesive and screws.

Here is what it looked like with all the inner shelves attached:

Next, I applied more adhesive to the attached shelves and dropped it on the remaining dado-ed vertical support.

Each shelf had to be adjusted so they fit perfectly into the dado grooves.  Screws were also inserted to secure the connections.

​Finally, I ran a 2×4 wood by the top shelf to serve as a mounting point for securing the bookshelf to the wall.

PRIMING AND PAINTING THE BOOKSHELVES

To complete this bookshelf, I put on 2 coats of primer, and then 2 coats of a special urethane acrylic cabinet paint.

I was worried about regular paint sticking to the books after sitting for some time, so I opted for this hard protective cabinet paint.

You also could use milk paint, which is a more natural paint and it turns out beautiful on furniture. We found this out with our mudroom makeover.

Eileen, who usually does all the painting, prefers milk paint on raw wood, which we learned after we did this built-in bookshelf. More details on this are at the end of the post – in the update section.

Then, with the help of Eileen, we carried the bookshelf upstairs and set it in place. Getting the shelf upstairs was no easy task, by the way.

I knew ahead of time that it was going to be a tight fit, but not impossible.

Here’s a picture of the shelf leaning, while we figured out just how to get it through the doorway. It was an extremely tight fit, but we made it.

The other bookshelf on the opposite side is actually slightly longer than the first one (due to the window not being perfectly centered on the wall).

So we knew ahead of time that the second bookshelf would definitely not fit in our stairway and would have to be constructed upstairs in the bedroom.

Attaching The Shelf To The Foundation Frame

Using some deck screws, I attached the bottom shelf directly to the foundation frame. The left side of the shelf (touching the wall) was secured directly to some wall studs.

Finally, I secured the 2×4 cross piece at the top to some wall studs using some lag bolts.

Aside from the 2×4, I used a countersinking drill bit to make the screw holes in the shelf. This made a clean hole for the screw to be countersunk without damaging the expensive birch plywood.

I planned on filling in these holes with wood putty later to hide the screw head completely.
​
Here’s a picture showing the shelf secured in place. It was really cool seeing Eileen’s vision start to take fruition.

BUILDING THE SECOND BOOKSHELF

Now it was time to start work on the second bookshelf that would sit on the right-hand side.

As mentioned earlier, it was a few inches longer than the first one and would have to be constructed in the bedroom, rather than in the garage.

I did as much as I could in the garage though.

First, I cut all the wood to the required sizes and routed the dados using my jig. I also painted the individual pieces in the garage as well.

Also, I had to be careful not to get too close to the edges of the shelves with the paint though.

The edges would slide in the dado grooves, and any paint (particularly the urethane acrylic paint) would increase the thickness of the shelves and make this step difficult.

Working between the garage and the upstairs bedroom meant frequent trips up and down the stairs.  Many times I would have a handful of tools to juggle.

Then during one of my frequent Google search sessions for tool organizing ideas, I came across bucket organizers for tools.  I didn’t even know they existed.

What a great way to repurpose the standard bucket.  So I purchased one and made my garage/bedroom commute a lot easier.

Here’s a picture of mine:

Next, I transported all the individual shelf pieces upstairs and started assembly with the help of some sawhorses.

It was a little more difficult to work in the bedroom due to the limited space, but it was manageable.

After the pieces were put together to assemble the bookshelf, I set it in place using the same steps I went through for the first bookshelf (securing to the wall and to the foundation frame).

Here is a picture of the right bookshelf partially assembled in the bedroom:

Here is a close-up showing the other vertical shelf support prepped with construction adhesive in the dados, ready to be attached to the rest of the shelf:

Both the left and right bookshelves were up at the point, and they were looking great.

Making The Window Seat

So next I started working on the middle portion – the seat and cabinets.

The cabinets were pre-fabricated ones I purchased online from Lowes. I got two of them to mount side-by-side. I just had to assemble them when they arrived.

You can also build the cabinets yourself – I later built these DIY cabinets for our mudroom.

Here is a picture of one of the cabinets after I assembled it:

To get the cabinets ready for installation, I built a framed housing for each. Then I slid the cabinets into the housing and screwed them in.

The top of the housing would also serve as the support for the seat.

Here is a picture showing the cabinet housing completed:

Here is a picture showing the installed cabinets, as well as the seat attached with some countersunk screws. The bookshelves were looking more complete with the window seat now in.

Building The Top Shelf

With the seat and cabinets in place, it was time to install the final shelf above the window and get ready for the trim work.

To start, I ran three 2 x 4’s across the top of the bookshelves (in between the top front of the bookshelves and the ceiling).

Their primary purpose was to provide a nailing surface for the crown molding.

In addition, the middle 2 x 4 (that bridged the two bookshelves at the top) was going to help support the middle shelf that ran above the window.

I didn’t use dado grooves for this window shelf. I just used construction adhesive and screws to attach two plywood shelf pieces in between the two end bookshelves.

The top shelf piece is also attached to the bridging 2 x 4 above.

This window shelf was really long though (the same length as the seat), so to prevent it from drooping in the middle, I added a divider in the center to hold up the bottom shelf to the firmer top shelf.

Installing Crown Molding And Baseboard

Now it was time to install the crown molding and baseboard.

This was a relatively straightforward step that adds a lot of pack for its punch.

I had installed crown molding in the kitchen of our previous home, so I was familiar with the procedure.

This time around though, I had a table saw, so the installation went even easier than before.

For an easy crown molding install, having an angled surface to nail the trim into place is key.

So I measured the angle of the crown molding (the angle it would make with the wall) and ripped some 2 x 4s with my table saw to match this angle.

I attached them directly to the 2 x 4s already mounted on top of the bookshelves. Then, I used my finishing nail gun to attach the crown molding.

Here is a close-up of the crown molding. It really added such a finishing touch to the built-ins:

The baseboard installed even easier. I just cut the pieces to length and secured them in with the nailgun.

The vent opening on the floor just needed a small top and bottom piece of the baseboard to blend in.

​​Here is what the baseboard looked like. The whole bookshelf project was really coming together:

Attaching Trim

With the crown molding and baseboard installed, it was time to attach the trim to cover the exposed edges of the plywood.

I couldn’t leave the bookshelves as they were because the plywood edges were very rough to the touch (easily leaving splinters) and were not very nice looking.

To save on costs, I decided to cut my own ¼” thick trim from 2 x 4s using my table saw.

I collected all the measurements I needed to cover all the exposed areas and got to work in the garage cutting the trim.

It worked out fairly well – although there were a number of knots in the wood causing several of the trim to break because they were so thin.

Also, other imperfections in the wood caused a few gouges in the cut trim.

So it definitely wasn’t perfect trim, but considering how cheap it was to make from 2 x 4s, it was worth it.

Besides, after the trim gets installed, I planned on patching up any flaws with wood putty.  Then, once painted, the trim would look flawless.

Here is a picture showing the installed trim (I use construction adhesive and my finishing nailer to attach them):

Finishing Touches On Construction

Construction of the window bookshelf was pretty much complete at this point. I was really pleased with how it was turning out, and Eileen was absolutely thrilled.

I did attach some beadboard paneling above the seat with construction adhesive and the finishing nailer.

All that remained now was to fill all the countersunk holes with wood putty, patch and smooth any imperfections in the trim, caulk any small gaps (mostly with the crown molding and baseboard) and then apply paint where necessary.

Painting The Built-In Bookshelves & Wall

Eileen hopped in at this point to take over the painting. She painted all remaining wood – going over the edges, getting the trim, and touching up areas here and here.

She also painted the areas to the right and left of the window (which were currently still the color of the walls). That really made the bookshelf pop.

Here is Eileen hard at work finishing off the project. The paint we used is linked above, but be sure to read our Update below on paint.

Using Our New Floor-To-Ceiling Bookshelf With A Window Seat

The built-in bookshelf project was now finished.  Eileen immediately filled up the shelves with all the books we had, freeing up much-needed space around the house.

She even made a really nice cushion for the seat from scratch. She used a cushion material she found and a piece of outdoor fabric that she had leftover.

She’ll tell you that she’s awful with the sewing machine, but I don’t believe it. Look how nice it looks (below):

Here are a few more of the completed built-in bookshelves with a window seat.

The total cost of the built-in bookshelves project was around $600 and took me a few weeks to complete. It was a lot of fun to work on, and the payoff was huge.

It’s such a great addition to our home. It definitely upped the value of our home, not to mention our enjoyment of it.

Eileen has a place that she loves for all of her books – it’s definitely her dream room now.

Who wouldn’t want an entire wall with floor-to-ceiling built-in bookshelves?!

To complete Eileen’s office, which is a sitting room off our bedroom, it needs some kind of doors. We are thinking about French doors or barn doors. What do you think would look best?!

And, if you’re trying to figure out how to style your built-in bookshelf and you’re a book hoarder like me, check out Emily’s post on how to style your bookcase if you’re a bookworm.

Three Year Built-In Bookshelf Update

Three years later, the bookshelf still looks amazing. 

The paint has held up great. It’s a smooth surface and easy to keep clean. 

There is one shelf that has too many heavy textbooks on it and needs a little support, but that was an easy fix. 

The trim needed to be recaulked/wood puttied because the ceiling was very uneven.

Some of the original caulk loosened up, and it needed another run.

Also, we would have chosen milk paint over the paint we used.

Not because of quality – but because we didn’t realize that a natural paint would hold up just as well and not expose us to any chemicals. 

Milk paint is beautiful on natural wood, and it’s so amazing to work with natural paint! Definitely check out our post on using milk paint on raw wood. 

And, we still haven’t put up any doors! Eileen would love to add French doors this year to make it feel like a separate room. That’s definitely on the project list. 

Not only was this sitting room wall completely transformed, but be sure to check out what we did to the other side of the room – the craft corner! 

This room has certainly come leaps and bounds from the desolate yellow sitting room. It’s absolutely Eileen’s dream room.

If you are wondering whether or not you have the skills to create this built-in bookshelf yourselves, definitely give our DIY instructions a thorough read. 

The only thing I had built before I got into DIY was a blanket fort. Just kidding. 

But seriously, you never know what you are capable of until you go for it. 

And, if you have questions, ask away!

More DIY Projects You’ll Love

• Love shelves just as much as we do?! Make these sliding storage shelves that are perfect for the garage or basement. They hold a TON!
• This entryway and mudroom makeover is my wife’s second favorite room in the house! This is another drastic makeover that she just adores.
• Want to start with an easy shelf? Make these simple picture ledges for less than $10.