The 8 Most Common Seam Types in Clothing Manufacturing

Plain Seam

The plain seam is the simplest construction — two fabric pieces stitched right sides together, then pressed open or to one side. It’s the default for most woven garments where high stretch or extreme durability isn’t the priority.

French Seam

A French seam encloses the raw fabric edge entirely within the seam itself, leaving no exposed raw edge on the inside of the garment. It’s commonly used on sheer or lightweight fabrics where a visible overlocked edge would show through or fray.

Flatlock Seam

Flatlock seams join fabric edge-to-edge rather than overlapping them, creating a flat, low-bulk seam that stretches with the fabric. This makes it the standard choice for activewear and other stretch garments where a bulky seam would cause chafing.

Overlock (Serged) Seam

An overlock seam trims and finishes the raw edge in one operation, preventing fraying while joining the fabric. It’s fast, cost-effective, and extremely common in knitwear and casualwear, though it offers less refinement than bound or French seams.

Bound Seam

A bound seam encases the raw edge in a separate strip of fabric or bias binding, creating a clean, finished look on both sides. It’s often used on unlined jackets where the inside of the garment is visible and needs to look intentional.

Lap Seam

A lap seam overlaps two fabric pieces and stitches through both layers, commonly seen as the flat-felled seam on denim jeans. It’s exceptionally durable and suited to workwear and heavy fabrics that need to withstand repeated stress.

Welt Seam

A welt seam is a reinforced variation often used in tailoring, where one seam allowance is trimmed and the other is topstitched over it for a structured, durable finish. It’s associated with a more formal, tailored construction quality.

Safety Stitch Seam

A safety stitch combines an overlock stitch with an additional straight lockstitch for extra seam security, commonly used where a seam needs to resist both fraying and pulling apart under stress. It’s a practical choice for garments that will see heavy wear or frequent washing.

Seam Types by Garment Category — Which to Specify

Matching seam type to garment category isn’t just an aesthetic choice — it directly affects whether the garment survives its intended use. A flatlock seam on tailoring looks under-finished; a plain seam on stretch activewear risks failing under normal movement.

Seam Strength Comparison by Type

Strength and stretch capability often trade off against each other — the strongest seams for woven, non-stretch garments (lap, welt) aren’t the right choice for a fabric that needs to move with the body.

How to Specify Seam Types in Your Tech Pack

Name the exact seam type for every major construction point in the garment, not just a general “standard seam” note — a side seam, hem, and armhole may each need a different seam type depending on stress and stretch requirements.

Include seam allowance measurements alongside the seam type, since the same seam type can be specified with different allowances depending on fabric weight and construction. If you’re finalising construction detail in your tech pack, our clothing manufacturing services team can review seam specifications before sampling begins.

Common Seam Specification Mistakes

Leaving seam type unspecified and assuming “standard.” Different factories have different defaults, and “standard” for one factory may be inappropriate for your fabric or garment type. Fix: name the exact seam type at every major construction point.

Using a low-stretch seam on stretch fabric. A plain or bound seam on activewear can restrict movement and eventually fail under stress. Fix: specify flatlock or another stretch-appropriate seam for activewear and stretch garments.

Choosing seam type based on cost alone, without checking garment use. The cheapest seam to produce isn’t always durable enough for the garment’s intended purpose. Fix: weigh seam type against how the garment will actually be worn and washed, not just production cost.

Inconsistent seam allowance across the same seam type. Varying seam allowance on the same seam type across different pattern pieces can distort fit at assembly. Fix: standardise seam allowance for each seam type across the full pattern set.

Not testing seam strength before bulk production. A seam that looks fine in a sample can still fail under repeated wear or washing at scale. Fix: request a seam strength check during sampling, particularly for high-stress garment categories.

FAQ

What are the most common seam types in clothing manufacturing?

The most common seam types are the plain seam, French seam, flatlock seam, overlock (serged) seam, bound seam, lap seam, welt seam, and safety stitch seam. Each suits different fabric types, stretch requirements, and finishing standards.

What seam type is best for activewear?

Flatlock seams are generally best for activewear, since they create a flat, low-bulk join that stretches with the fabric and reduces chafing. Overlock seams are also common, particularly for less performance-focused stretch garments.

What is the difference between a French seam and an overlock seam?

A French seam fully encloses the raw fabric edge within the seam itself, giving a clean finish suited to sheer or delicate fabrics. An overlock seam trims and finishes the raw edge separately with a serging stitch, and is faster and more cost-effective but less refined in appearance.

Why does seam type matter for a tech pack?

Seam type affects a garment’s strength, stretch, bulk, and finish, so leaving it unspecified means the factory applies its own default rather than what your garment actually needs. Naming the exact seam type at each construction point avoids fit and durability issues later.

What is BS 3870?

BS 3870 is the British Standard that classifies and defines stitched seam types used in clothing manufacturing. It provides a shared reference point that brands and factories can use when specifying seam construction in a tech pack.