How to Re-seal Seams on Rainwear and Stop the Leak

Why rainwear leaks at the seams

The fabric in rainwear is waterproof, but the moment it is sewn together, thousands of needle holes are punched along every seam. From the factory these holes are covered on the inside with heat-welded seam tape that keeps water out. It is this tape – not the fabric – that fails first: after many washes, heat and flexing it starts to lift, crack or peel off. Then water runs in through the needle holes even though the outer fabric is intact. Typical leak points are the shoulders, hood, underarms and crotch seam, where the garment bends and stretches most.

Find out where it actually leaks

Before you seal anything, you need to know where the problem is. Turn the garment inside out and go over the seams in good light.

1. Turn the rainwear inside out and look for seam tape that is bubbling up, curling at the edges, cracked or already fallen off.
2. Feel gently along the seam with a finger – loose tape gives way and feels uneven.
3. Test with water: dry the inside, put water on the outside over a suspect seam, and watch whether it comes through on the back.
4. Mark the leaking seams with a piece of tape or a washable marker so you can find them again.

How to seal the seams

Both seam tape and liquid seam sealer only bond to clean surfaces. Skip the wash, and the sealing will let go again after a short time.

1. Wash the garment with a technical wash made for shell and rain garments, and let it dry completely – no moisture left in the seams.
2. Turn the garment inside out and gently remove seam tape that has already let go. Leave tape that is still firmly attached in place.
3. For liquid seam sealer: apply a thin, even layer along the stitch line on the inside (and over the seam on the outside too), and let it cure fully before wearing.
4. For seam tape: lay the heat-activated tape over the seam on the inside, cover with baking paper, and press with an iron on low heat until it bonds. Let it cool first.
5. Finally, test with water again before you trust the garment in real rain.

Seam tape or liquid sealer – which to choose?

Both seal the needle holes, but they suit different situations:

• Seam tape (heat-activated) gives the neatest, most factory-like result and is best when the original tape has peeled off over a longer run – but it needs the right type of tape and careful, even heat.
• Liquid seam sealer is easier to control on short stretches, tricky zones like the hood and underarms, and where the tape has only just begun to lift – but it is less invisible and needs plenty of time to cure.

Don't confuse a seam leak with worn-out proofing

It is easy to think the jacket is 'leaking' when it has simply lost its water-repellent surface (DWR). Then the outer fabric soaks up water and feels clammy across the whole surface, but the water is not necessarily coming through – that is a proofing problem, not a leaking seam. A seam leak, by contrast, shows up as water entering at a specific, limited point along a seam while the rest of the garment stays dry. Check both: if the fabric is dark and soaked over large areas, the garment needs re-proofing; if water enters at a single seam, it is the tape that needs sealing.

Send the rainwear to us

If the rainwear is expensive, technical or important to you, or the seam tape has let go in many places, you can send the garment to us. We look at the seams and outer fabric and find the right solution for that specific garment, and can re-proof the outer fabric in the same round if it also needs it. If the rainwear needs a repair – a tear, a zip or a worn edge – we can handle that at the same time. You order online, and you see the price before you order.

Frequently asked questions