How to join binding strips with diagonal seams

Posted by Amanda Bagin on

how to join binding strips with diagonal seams

I consider the binding of a quilt the victory lap. It's the final step of the process after many hours of hard work. In this series of blog posts, I'll be sharing my top 3 tips for making the binding for your quilt. First up is how to join binding (or sashing!) strips with diagonal seams. You'll often see this at the very end of a quilt pattern in the "finishing your quilt" section where it will often say "bind as desired." 

Why do we use diagonal seams in binding? Using this method helps distribute the seam to reduce bulk in the binding. Also, a diagonal seam is typically less noticeable than a straight seam (for most fabrics). Let's get started.

Supplies you'll need: 

  • Binding or sashing strips
  • Rotary cutter and cutting mat
  • Acrylic ruler
  • Pencil or marking tool
  • Sewing machine

First, you'll cut your binding strips if you haven't already. Typically a pattern will call for 2.5 inch wide strips by width of fabric (WOF), along with the number of strips you'll need for the binding to reach all the way around your quilt (note: there is always extra binding to spare). However, even though the Scenic Road pattern calls for 2.5" strips (that seems to be the pattern standard), I actually prefer 2.25" strips. 

scenic road quilt close up of binding

Once your strips are cut, you can start joining them together. Typically if you are making sashing, borders or binding, it's easiest to join all the strips into one very long strip first.

Take the ends of two strips and place them together diagonally at a 90 degree angle, right sides together (also abbreviated as RST in patterns). This means if you have patterned fabric or fabric where there is a side that you want showing on your quilt top, place those two sides together, facing each other. In these photos, I'm using Art Gallery Fabrics Pure Solids in Snow so there is not necessarily a "right side" that the untrained eye would notice and in this case it won't matter. This would be the same case for Kona Cotton and many other brands of solid quilting cottons.

Don't worry about trimming the selvages (the ends of the fabric) off at this point; they will get trimmed later. Just shift the fabric slightly to let the selvages hang over the overlapping strips as seen below.

two strips right sides together

Next, we will mark where we want to sew. Carefully lie a quilting ruler on top of your two RST strips diagonally. Now, if you mark and sew diagonally the wrong way, you'll find yourself hanging out with your seam ripper (speaking from experience!) so it's important that the two "ends" of the strips are both showing on the same side of your ruler, as seen below. Using a pencil and your ruler, mark a line across the diagonal.

ruler diagonally lying over two binding strips
pencil mark on two binding strips right sides together

Next, we will pin on either side of the marked line. Make sure that the two strips are still lined up at a 90 degree angle and that your marked line reaches the outer edges of the strip on the bottom. Some quilters are avid non-pinners, and if you are just starting out as a quilter you will learn whether you fall in that camp fairly quickly. But for the sake of this tutorial and keeping everything nice and straight, we will pin, just to be safe!

pins on binding strips Right sides together

Next, we sew! Sew a line directly on your marked line with your sewing machine. It will look something like the photo below. 

sewn line on two binding strips

Now that the two strips are adjoined, we will trim off the selvages. Using your quilting ruler, line up the 1/4" line on the ruler with the sewn line. Importantly, the 1/4" overhang of the ruler should be on the side of the sewn line with the short ends of the strips, as shown below. This will give you a perfect 1/4" seam. 

quilting ruler with 1/4 line lined up on sewn line

Using your rotary cutter, cut up against your ruler leaving behind a 1/4" diagonal seam. You can also carefully trim the "dog-ears" (little overhanging triangles) as well with your rotary cutter or your snips.  

trimmed one-quarter inch diagonal seam

Open up your strip and press your seams open with an iron. While everyone has their pressing preferences, I have found that pressing open for binding and sashing strips helps keep the bulk of the seams down.

completed diagonal seam on binding strips

We all have different preferences for constructing quilts. The main goal is to find a way that brings you joy - quilting should be fun! Do you join your diagonal seams in a different way? Do you prefer using straight seams? Let me know in the comments!

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