How to Make a DIY Bay Window Seat Cushion

Item # X-HT-300129

Turn any window seat into a cozy nook for reading or looking out the window with a comfy cushion. If you have a window seat, kitchen banquette or other built-in bench that could benefit from a cushion, we’re breaking down the process of sewing your own DIY window seat cushion in this step-by-step how-to video.

DIY Window Seat Cushion

The window seat in need of a cushion was a long bench in the curved opening of a bay window. To get the best fit, we decided to make one, extra-long bay window seat cushion with angled sides to match the shape of the bench. We used Dura-Skrim® Patterning Material to trace the shape of the bench to be sure we had the angles just right.

When sewing a long cushion like this it can be difficult to keep all the pieces properly aligned. To aid in this, we like to use match-up marks. These are small snips you make in the seam allowance on the fabric at the center of all of the panels and other key points around the fabric. Then when you’re sewing the panels together you can align the marks to know that everything is going back together just as planned. We carefully explain the process of creating and utilizing match-up marks in the video.

In the video you’ll also learn how to use Sailrite’s Fabric Calculator to determine the proper amount of fabric to order, how to sew your own bias piping, how to attach piping to fabric panels with tight angles, how to glue and cut foam, and much more.

Video Chapters:

  • Measuring & Patterning Window Seat Shape – 0:45 min.
  • Using Sailrite's Fabric Calculator – 2:08 min.
  • Patterning & Cutting Plates – 3:23 min.
  • Cutting Boxing – 9:38 min.
  • Creating Zipper Plaque – 12:01 min.
  • Making Piping & Sewing to Plates – 18:29 min.
  • Sewing Boxing & Zipper Plaque to Plate – 27:02 min.
  • Basting & Sewing Assembly to Final Plate – 34:30 min.
  • Gluing & Cutting Foam – 39:37 min.
  • Inserting Foam in Cushion Cover – 42:39 min.
  • Materials List – 43:55 min.

Materials List:

  • Dura-Skrim® Patterning Material #122460
  • Décor & Upholstery Fabric (we used a P/K Lifestyles upholstery fabric)
  • Coats Extra Strong® Tex 70 Nylon Upholstery Thread (we used Black #104813)
  • Medium 5/32" Welting Cord #122451
  • Seamstick 1/4" Basting Tape for Canvas & Upholstery #104167
  • YKK® Continuous Zipper Chain #5 Black (VISLON®) #100029
  • YKK® Zipper Slider #5 Black Plastic Single Non-Locking Pull (VISLON®) #103179
  • CushionRite® Premium Foam (Medium) #124234

Tools List:

  • Gingher® 8" Scissors Right Handed #19104
  • Scribe-All Water Soluble Marking Pencil (we used White #120681)
  • Multiuse Pins 1-1/2" #102985
  • Sailrite® Fabricator® Sewing Machine with Workhorse Servo Motor #400500
  • Sailrite® Canvas Patterning Ruler #107040
  • Deluxe 5-1/2" Magnetic Sewing Guide #103597
  • Clear Acrylic Ruler 6" x 24" #102400
  • Comfort Grip Rotary Cutter 60mm #9655
  • Self Healing Rotary Cutting Mat 24" x 36" #120257
  • Cording foot to sew piping, if required (we used the 3/16" Cording Foot Set #103281 for the Fabricator)
  • Sailrite® Blade Foam Saw #121244 or an electric kitchen knife
  • Foam Lock Spray Adhesive #120464
  • Tape Measure, Marker, Straightedge

Find all the materials and tools for making your own window seat box cushion right here at Sailrite. Have questions on the video? Want to share your project success? Leave your questions, stories and photos in the comment section below!