Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

MirandaCameron Button Up, Guest Bloggers, Sewing Tutorials6 Comments

How to Sew a Flat Felled Seam

Did you know that the Cameron Button Up includes instructions for four different seam finishes? Whether you prefer overlocking, french seams, or want to sew something more traditional like a flat felled seam, Cameron has you covered! So what exactly is a flat felled seam, and how do you sew one?

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Flat felled seams are one of the sturdiest seam finishes around. They are traditionally used in button up shirts, trousers, and other types of “workwear” (take a look at the inseam of a pair of RTW jeans, and you will likely find a flat felled seam). Because one side of the seam is folded over to enclose the other, the seam is secured with two lines of stitching instead of one. This is great for garments or seams that undergo a lot of stress during daily wear, or for pieces you simply want to last a long time.

The other major benefit of a flat felled seam is that you don’t need any special tools or stitches to achieve it—just a regular straight stitch on your sewing machine! It’s not the fastest technique, but because the raw edges are completely enclosed on both sides of the fabric, it’s an option that looks just as good on the inside as it does on the outside. And who doesn’t love a tidy seam finish?

There are only two exposed seams in the Cameron Button Up: the side/arm seam and the armscye (sleeve attachment) sleeve. We’ll be attaching the armscye sleeve first so we can tackle the side and arm seams all at once later. Since this seam is curved and a little tricky to sew, we highly recommend doing a test seam first if this is your first time using this technique! Practice seams are a great way to build your skills and boost your confidence before sewing your final garment.

Sewing the Armscye Seam

Start by sewing two lines of line of basting stitches per the instructions, and gathering them slightly to create a rounded shape in the sleeve cap.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog
Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

With right sides together and matching notches, pin the sleeves to the shirt. Note that the notch at the top of the sleeve cap aligns with the notch on the back yoke, not the shoulder seam. Use as many pins as necessary here to match the curved edges.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Sew the sleeve and the shoulder together using a 5/8” (1.6 cm) seam allowance, and trim the body seam allowance to 1/4″ (0.6 cm). Take special care not to trim the sleeve seam allowance here.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Fold the untrimmed seam allowance (the sleeve) around the trimmed one (the body), encasing the raw edge within the fold and press. The bias cut of the armscye will help you fold the fabric around the curve, and a tailor’s ham can help with pressing.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog
Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog
Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Now, press the seam allowance towards the body. The trimmed seam allowance will be encased within the fold.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog
Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Pin in place* and topstitch. Because this is a curved seam, it will be trickier than normal to sew. Go slowly, and be kind to yourself! It’s nearly impossible to stitch this seam perfectly.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

*I personally find it easier to skip the pins and use an awl (or other pointy object, like a pencil) when needed to “tuck” the seam allowance back into place as I sew.

To achieve a more even line of stitching on the right side of the garment, try to use the stitch line as your seam guide rather than the edge of the folded fabric:

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Sewing the Side/Arm Seam

After the shoulder seams are sewn, it is time to sew the side and arm seams. This is a good time to baste fit the garment and adjust as necessary. Refer to the Cameron instructions for more advice on how to do this.

We will be following a similar sequence of steps to flat fell this seam. First, with right sides together and matching the underarm seams, pin the side and the sleeve seams of the shirt.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Starting at the sleeve and working towards the hem, sew using a 5/8” (1.6 cm) seam allowance. Trim the back seam allowance to 1/4” (0.6 cm). Just like the armscye sleeve, we want to make sure to leave the front seam allowance untrimmed.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Fold the untrimmed seam allowance (the front) around the trimmed one (the back), encasing the raw edge within the fold and press.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog
Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Press the seam allowance towards the back. The trimmed seam allowance is now encased within the fold. Pin in place.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Topstitch, this time starting at the hem and working your way towards the end of the sleeve. An awl or other pointy object can be helpful for keeping your fabric in place, especially when sewing over other the armscye seam.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog
Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Things will be tight as you start to sew into the sleeve, but it is possible to topstitch the entire sleeve—we promise! Go slowly and take care to readjust the fabric every inch or so, making sure to leave the needle and presser foot down as you readjust.

Flat Felled Seams Tutorial (Cameron Button Up) - Helen's Closet Patterns Blog

Congrats! You’ve just sewn flat felled seams on your new Cameron. Not only is it a clean finish, you now have a garment that can stand the test of time.

Note: the method covered here will place the seam allowance on the inside of the garment, meaning there is only one line of topstitching that shows on the outside of the garment. If you’d prefer two lines of stitching to show on the outside, simply follow the same instructions above, but make sure to start with the wrong sides of the fabric together instead.

About the author

Miranda

Miranda Milke is a freelance writer and content marketer with a passion for all things sewing and textile arts. You can find her work on Instagram @stitchinginspace and on her blog at stitchinginspace.com.

6 Comments on “How to Sew a Flat Felled Seam”

  1. Thanks for a great tutorial! I’ve used the seam often making pants and flags, but want to try it on a classic shirt and appreciate having the detailed order of operations you’ve provided.

  2. Thank you for the clear instructions. I find the digital lines showing stitching really helpful. I would like to add a flat felled seam below a lapped side zipper on a pair of shorts…I am planning to use the Jenny pattern from Closet Core. Please let me know if you have any recommendations for this modification. I suppose I could simply add edge and topstitching to the side seam to give it a similar look without the flat felled seam.

    1. Hi Emily! I find the best way to work out construction like this is to cut some muslin and try it out! You can even use your zipper and rip it back out later.

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