In the Details: Why flatlock seams are important for plus-size clothing and design

by Allison Prescott September 22, 2017 2 min read

In the Details: Why flatlock seams are important for plus-size clothing and design

In the Details is a series where we dive deep into design details at JunoActive. Thoughtful design and durable fabrics are at the core of our design process. Here we explore the extra details that go into our plus-size activewear, swimwear, and underwear to make them as comfortable, functional, and long-lasting as possible. 

Flatlock seams. It’s very possible you’ve never heard of them, but they are super important to us as a design element in all of our plus-size clothing.

Often, seams are sewn together with two layers of overlapping fabric, like an overlock or serged stitch. The bulk of the extra fabric around the seams can create an uncomfortable pressure point along the seam and can even lead to chafing, depending on what activity you’re doing.

Fleece Flat Lock Seams
You can see the flatlock seam in action on the left and right sides of the photo on this fleece jacket.

You’ve definitely worn pieces with overlapping stitches and seams before—you’ll notice your jeans are probably stitched together with overlapping fabric. Laying on your side in a pair of bottoms with overlapping seams can get quite uncomfortable after a while—especially if there’s a Netflix marathon currently unfolding. You’ll see an indented line on your skin that may even itch due to the imprint on your skin from the seam.

That’s why we construct many of our pieces with a flatlock seam: since the flatlock method doesn’t require a seam allowance, there’s no extra fabric creating a bulge along the seam. Lounging on your side or engaging in fast-paced activities are a lot more comfortable with flatlock seams, as they greatly reduce chafing and pressure on your skin. Although flatlock seams can offer an element of style, like contrasting thread to add a pop of color, we mostly use flatlock seams for comfort.

Here are a few examples of JunoActive plus-size pieces that use flatlock seams:

QuikWik Plus Size Side Pocket Capris

149309_BKSOL_OM (1).jpg

Our pocketed capris are everything you need for walks or runs so you can take your phone, keys, and whatever else you want with you. The flatlock seam detail is on both the inner and outer leg, making sure you stay comfy on the move. Shop them here.

QuikWik Plus Size Black Leggings


A staple in every woman’s wardrobe. The perfect thigh barrier under dresses and skirts for cool weather, or great for any yoga class or brisk jog outdoors. The flatlock seams along the outer side of the leg mean you can lounge and move in these without worrying about excessive rubbing or discomfort. Shop them here.


AquaCurve Plus Size Swim Rash Guard


Italian fabrics and an insanely good chlorine-resistant Lycra blend will keep this shirt lasting and lasting. The flatlock seams here will reduce the chance of chafing and keep you comfortable in and out of the water. Perfect for various beach activities—especially for those who are looking for extra coverage and protection on their shoulders from the sun. Shop it here.

AquaCurve Plus Size Tank Suit


A classic JunoActive swimsuit. The side paneling detail gives you a flattering silhouette, while the flatlock seams deliver ultimate comfort while you’re busting out laps. Shop it here.

Allison Prescott
Allison Prescott

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JunoActive Size Charts

US Size Chart

Size XL 1X 2X 3X 4X 5X 6X
Women's 14/16 18/20 22/24 26/28 30/32 34/36 38/40
Bust 40-42 44-46 48-50 52-54 56-58 60-62 64-66
Waist 32-34 36-38 40-42 44-46 48-50 52-54 56-58
Hip 44-46 48-50 52-54 56-58 60-62 64-66 68-70

Euro Size Chart

Size XL 1X 2X 3X 4X 5X 6X
US 14/16 18/20 22/24 26/28 30/32 34/36 38/40
Euro 44/46 48/50 52/54 56/58 60/62 64/66 68/70