Sewing a waterproof fabric puts holes in it, and no technique changes that. The whole approach is to make fewer, smaller holes and then seal them.
Use the finest needle the fabric will take — a 70/10 or 80/12 microtex on most coated nylon and polyester. A large needle makes a large hole, and the hole is the leak.
Lengthen the stitch to about 3 to 3.5 mm. Fewer stitches per centimetre means fewer holes and a stronger, less perforated seam line.
Never pin outside the seam allowance. Pin holes stay open. Use clips.
Do not unpick. Test everything on a scrap first, because a removed seam leaves a permanent dotted line.
Deal with the coating sticking. A walking, roller or non-stick foot, or tissue paper between the fabric and the foot.
Use flat-felled or enclosed seams where you can. They put the stitching under a fold, which sheds water far better than an exposed seam.
Seal the seams. Seam tape needs a heat press; liquid seam sealer applied along the stitching from the inside is the practical home alternative and works well enough if applied carefully to a clean, dry seam.
Place seams where water does not sit — off the top of the shoulder and away from the top of a bag.
Do not press with a hot iron. Coatings and membranes melt. Topstitch seams flat instead.
Questions people actually ask
Can I make a genuinely waterproof garment at home?
Close, with careful seam placement, enclosed seams and liquid seam sealer. Taped seams to a commercial standard need equipment most people do not have.
Which needle for a coated nylon?
A 70/10 or 80/12 microtex. The sharp slim point makes the smallest clean hole, which is exactly the goal.
Last reviewed 2026-08-11