If you’re a freelance fashion designer or technical designer, knowing the right seam types is important to make sure you’re creating production ready tech packs that manufacturers will understand.

For example, if you’re making knit joggers vs denim pants, your joggers will require flexible seams that allow for comfort and movement. Since knit material can unravel, serging the seams is a must. On the other hand, denim jeans will require something sturdier with a clean finish like a flat felled seam.

In my 15+ years working as a fashion designer, I’ve handled different types of garments, from yoga clothes to ski jackets, that use different construction methods and seams. In this guide, I’ll share what I’ve learned about the best seam types for each part of your garment. 

What is a Seam?

This sounds basic, but many beginner fashion designers confuse seams with stitches. A seam is where one or more pieces of fabric are joined together. This is usually done by stitching them together, but in some cases, seams can also be glued or bound together using heat or adhesives. Seams can vary in appearance and construction method depending on the type of fabric, the purpose of the garment, and the desired look. 

Stitch vs Seam

Stitches are used to hold fabric pieces together to form seams. Take the flat felled seam, for instance. In this type of seam, two fabric edges are first stitched together using a lockstitch. Then, one side of the seam is folded over the other, covering the raw edge. Finally, another stitch is made to hold the folded edge in place. This creates a neat and strong seam, commonly found in jeans.

Types of Seams in Garment Construction

There are 8 seam classes that encompass different seam types:

• Class 1 – Superimposed Seam
• Class 2 – Lapped Seam
• Class 3 – Bound Seams
• Class 4 – Flat Seams
• Class 5 – Decorative Stitching
• Class 6 – Edge Neatening
• Class 7 – Applied Seam
• Class 8 – Enclosed Seam

It’s best practice in tech packs to include the type of seam and a visual of how it should be sewn. While the classes above are fairly universal, a picture is worth a thousand words. And remember, if you’re manufacturing overseas, there’s a chance the workers’ first language isn’t English.

1. Class 1 – Superimposed Seam:

The most common type of seam in garment construction, a superimposed seam is formed by placing fabric layers on top of each other and stitching them together with a straight stitch. This stitch can be a lockstitch, chain stitch, serged stitch, etc.

Common Types of Class 1 Seams: plain seam, French seam

Examples: basic garment construction, joining side seams, outer edges of cuffs/ waistbands/ collars

2. Class 2 – Lapped Seam:

This involves overlapping fabric layers and stitching them together along the overlapped edge. This seam creates a flat, durable join suitable for heavy-duty garments and fabrics such as vinyl, denim, and leather. 

Common Types of Class 2 Seams: flat felled seam, overlapping seam, welt seam

Examples: side seam and inseam of denim jeans, button-down shirt seams, outerwear seams, yoke seams

3. Class 3 – Bound Seams:

Fabric edges are enclosed within bias tape or binding, providing a neat finish. This seam is ideal for delicate fabrics and lightweight garments where traditional seam allowances may cause bulk or fraying. Bound seams can also be used for decorative purposes through the use of contrasting color binding. 

Common Types of Class 3 Seams: bias-bound seam, Hong Kong finish

Examples: binding around necklines and armholes, attaching waistband to skirt or pants, finishing raw edges of outerwear, decorative binding

4. Class 4 – Flat Seams:

Flat seams offer minimal bulk by “butting” fabric layers flat against each other and stitching them together with straight or zigzag stitches. In this type of seam, the fabrics joined together do not overlap and are simply held together by the stitches.

Examples: lingerie, activewear, underwear, swimwear

5. Class 5 – Decorative Stitching:

This seam category encompasses a wide range of decorative seams and techniques, including topstitching, piping, and appliqué. 

Common Types of Class 5 Seams/Stitches: decorative stitch, piping, pin tuck  

Examples: decorative stitches on garments, pin tucks on blouses

6. Class 6 – Edge Neatening:

You’ll usually see this type of finishing on sleeves and bottom hems of your T-shirts. This type of seam prevents fraying and provides a clean edge using various seam finishes such as overcasting or serging. 

Common Types of Class 6 Seams: clean finish hem, folded edge hem, serged edges

Examples: sleeves and bottom hems, facings

7. Class 7 – Applied Seam:

This seam class encompasses a wide range of techniques for attaching components to the garment’s body such as adding in collars and cuffs or extra materials like lace or elastic.

Examples: attaching ruffles on sleeves, installing zipper, knit collar & cuff seams

8. Class 8 – Enclosed Seam:

Involves finishing a single layer of fabric onto itself by folding in the edges and stitching. 

Examples: single-ply waistbands and belt loops

Additional References for Garment Construction

Now that you’ve learned all the necessary seam classes and seam types, you can check out my other guides on the 9 Essential Types of Stitches for Garment Construction and Technical Callouts in Tech Packs, along with my Garment Construction Dictionary to make sure you’re making production-ready tech packs!