A DIY window seat with storage is a fantastic, budget-friendly way to transform a boring window wall into a beautiful focal point. This simple, step-by-step tutorial will walk you through the process of building a window seat from scratch using pre-made IKEA cabinets in just a few hours!
This post was originally published on July 11, 2018 and has since been updated.
I am a HUGE fan of having window seats in a home. Not only do they give you a spot to relax, but they can provide large amounts of storage at the same time.
I feel like just about every house has a spot to squeeze one in, and if you’ve got a boring wall with a window on it, then I say do it! Our method for building a window seat is super easy, and using pre-built IKEA cabinets makes it end up looking professionally built!.
We added a window bench seat with storage in our dining room makeover earlier this year and it’s now one of my favorite spots to relax and lounge in our home. 🙂
I hope this simple, step-by-step tutorial for how to build a window seat with storage inspires you to build one in your home!
If you scroll to the bottom there is a simplified, printable version of this tutorial too. Feel free to print it to have with you while you’re building!
HOW TO INSTALL A BUILT-IN
DIY WINDOW SEAT
Before we get to the actual building, I want to talk about the standard dimensions or sizes of a window seat bench with an upholstered cushion.
How tall should a window seat be?
We recommend making your window seat between 18-20″ tall (standard chair height) while getting it as close to the bottom of the window frame as possible.
With our method shown below, the IKEA cabinets are 15″ tall, so we added 3.5″ (1×4 on edge) underneath to get to the 18.5″. Plus, you have the height of the cushion so that gets us in that range nicely.
How wide should a window seat be?
You want your window seat to be at least as wide as your window.
You can always go wider, for example if you plan to do built-ins on either side of the window seat, which might dictate making your seat wider to accommodate.
You’ll see we did ours a few inches past the window to fill in the gap between our built-ins.
How thick should a window seat cushion be?
We made our first window seat with 2″ foam and it was NOT thick enough. Go with at least 3″ high-density foam and add batting under your fabric too.
I mean, if it’s going to be a spot you sit on to relax, you want it to be cozy! 😉
Consider your space.
I’d encourage you to take some time to think through these dimensions based on your space before you get started on your window seat DIY project.
The IKEA cabinets come in 30″ and 36″ widths, so if you’re installing between two cabinets or with wall/cabinet on the sides, you’ll need to get as many as you can based on that fixed width.
If you’re installing this on its own, without anything around it, then you’ll want to go with a width that’s divisible by the 30″ or 36″ cabinets so as not to make things more complicated.
Once you feel confident in how your window seat will fit, get building!
Installation Instructions for a Built-In DIY Window Seat with Storage
STEP 1: BUILD THE BASE FRAME
The first thing you need to do is build a base for your seat.
Since the IKEA cabinets are only 15″ tall, and a standard chair is 18-20″ high, you’ll need to raise up the cabinets by 3-4″ to get them to the right height for sitting.
A 2×4 turned up (technically 3.5″ tall on edge) is the perfect way to prop them up and give them a stable and level surface to install on.
Build a rectangle out of your 2x4s that is as wide as you want your window seat to be, and 20″ deep. The IKEA cabinets are 24″ deep, so they will overhang the support on the front by 4″ creating a toe kick. Then install support runners every 12″ or so.
Because we were covering up our floor vents, we made our support base slightly less than 20″ deep to align the back of it with the back of the vents. This created a better set up for forcing our air out from under the base of the seat.
You’ll want to make sure the base structure is level both side-to-side and front-to-back and then line it up against the wall and screw it either into the floor, the wall, or in our case, the cabinets on either end.
STEP 2: INSTALL THE IKEA CABINETS
Measure the full width of your window seat and decide how many 30″ or 36″ cabinets will be best for your space.
We had a gap of about 126″ so we purchased 4 of their 30″ cabinets to fill the gap as much as we could with cabinetry.
If you’re installing this bench on its own (without anything on either side of it) then you can skip the spacers. But be sure you’re making your window seat a width that can be achieved using the 30″ or 36″ dimensions of the cabinets.
Once you’ve got all of the cabinets assembled, place them on your base and measure the gap you need to fill with side trim.
You’ll want to center your cabinets, so take the gap and divide by 2 to get the size of spacer trim you’ll need to install on each side.
Cut your 1×3 board to that size, clamp it to the cabinets, and screw them into place.
Once the spacer trim is installed, go back and screw all your cabinets together, and to the base support. Then, install the cabinet doors.
STEP 3: INSTALL THE FLOOR TRIM
Next, you’ll want to install some pretty floor trim underneath your toe-kick area.
Like I mentioned, we also installed two air vents for our HVAC to push the air out from under the bench.
We ripped the 1×6 trim down to the right height, nailed it into the base support and painted it white to match the existing trim and cabinets.
STEP 4: BUILD AN UPHOLSTERED BENCH SEAT
Our DIY window seat wouldn’t be complete without an upholstered top!
I’ll be honest, my husband did the upholstering for this project. 😉
We started by simply cutting 3/4″ plywood to the size of the bench (we needed two pieces because our seat is longer than 8′) and pocket-hole screwing it together.
Then, we cut 3″ high-density upholstery foam to that same size.
From there, we glued down the foam using spray adhesive, wrapped it with batting which was then stapled to the bottom, and then wrapped and stapled the fabric over it.
I apologize for a lack of pictures for these steps, my husband was on photo duty and he tends to forget to snap them while he’s focused on working…
Once the upholstered seat was done, we simply installed it on top and then screwed it into place from underneath inside a few of the cabinets!
STEP 5: DECORATE
Of course, a DIY window seat isn’t complete without pillows, blankets, and faux fur! 😉
We installed some simple sconces for reading and curtains on either side of the window in the corners for softness.
I also placed a small side table (actually technically a plant stand) next to ours for setting down drinks, books, phones, etc.
You can find sources for all the items in this dining room here.
Seriously, did functional storage ever look so good?! I now have all of my fine china and a bunch of my crafting supplies hidden away but easily accessible.
So, what do you think? Are you ready to install one in your home?? Do it!! 🙂
As promised, here are the printable instructions:
- Build a support structure out of your 2x4s on edge. This should be as wide as your overall window seat and 20" deep (to allow for a 4" toe kick) with support runners ever 12" or so.
- Assemble the IKEA cabinets and center on top of your base structure. If there's any gap between the edge of the cabinets and the overall width of your seat, cut spacers from your 1x3 to install between the cabinets or on the ends to accommodate.
- Use clamps to screw the cabinets to the spacers and then screw all the cabinets into the base structure.
- Install your cabinet doors then rip down your 1x6 board to the height of your toe kick space underneath and cut a piece as wide as the base of your seat. Install it underneath to hide your support structure and paint white.
- Cut a piece of 3/4" plywood and 3" high-density foam to fit over the entire window seat.
- Spray your plywood with the adhesive and place the foam on top.
- Cover your foam with batting, turn over the top and staple it in place on the bottom.
- Turn the top back over, cover your batting with fabric, turn over the top and staple in place on the bottom.
- Install the upholstered top by screwing it in from underneath inside the cabinets.
If you're building a window seat without anything built-in on either side, it's easiest to build one with a width that's divisible by 30" or 36" so you don't have to space out your cabinets.
Try for an overall height of 18-20", a width at least as wide as your window, and be sure to use 3" foam!
As always, let me know if you have any questions.