Why seams matter
Sewing punches thousands of tiny holes through a waterproof fabric. Seam tape bonds over the stitch line and closes them. On a waterproof jacket the seams are usually the weakest point, which is why tape selection, tape maps and inspection are central to hard shell quality. Read the full explainer in seam sealing explained.
Choosing seam tape
| Laminate | Tape type | Notes |
|---|---|---|
| 2-layer and 2.5-layer | 2-layer tape applied on the membrane side | Used with a loose liner or printed protective layer |
| 3-layer | 3-layer tape matched to the backer | Strong adhesion on a smooth backer; width set by seam type |
| Stretch laminates | Stretch-compatible tape | Tape must flex with the fabric |
Tape widths commonly range from about 13 to 20 mm. The exact choice depends on seam type and curvature.
Planning the tape map
- Critical vs full taping: full taping seals every seam on a waterproof garment; critical taping seals the most exposed seams and suits lower price tiers
- Seam design: avoid sharp radii and bulky seam intersections that cause tape wrinkles and lifting
- Zipper and pocket ends: plan where tape stops and starts around openings. See waterproof zippers and trims
- Pattern link: tape-friendly seam allowances are set at the pattern stage
Application and inspection
- Hot-air tape machines heat the tape adhesive and press it onto the seam at controlled temperature, speed and pressure
- Operators check tape alignment and tension as they go
- Inspectors look for wrinkles, gaps, lifting edges and adhesive spill-through
- Samples are tested for adhesion and, where agreed, water resistance on seams
Common defects and what prevents them
| Defect | Cause | Prevention |
|---|---|---|
| Wrinkled or lifted tape | Too much tension, curvature or wrong temperature | Tape-friendly pattern, machine settings tuned to the fabric |
| Gaps at seam intersections | Tape not overlapped or cut correctly | Tape map with overlap rules and inline checks |
| Adhesive failure | Wrong tape for laminate, contamination or wrong settings | Tape matched to the backer and test strips before bulk |
| Pinholes at needle stitches | Tape too narrow or off-centre | Correct tape width and alignment checks |
Last reviewed: