Repair & Maintenance

Sealing tent seams (SIL and PU coating)

Tent seam being treated with a sealing agent.

When a tent seam leaks, it is because the original sealing has broken down. Here is how to apply a new layer — and why PU and silicone need entirely different methods.

When a tent seam starts to drip through, it is because the original sealing has given way. The repair is not difficult, but it depends on whether the tent has PU coating or silicone coating (SIL). They need entirely different sealing agents.

How to tell the difference

PU coating (polyurethane):

  • The inside of the tent fabric has a clear plastic-like coating
  • The seams are often taped on the inside with a thin vinyl film
  • The fabric feels slightly tacky when new
  • Common manufacturers: most budget and mid-range tents

SIL coating (silicone):

  • The fabric feels greasy on both sides
  • Seams are usually not taped when new — the silicone seals on its own when the fabric is sewn together
  • Light, often expensive
  • Common manufacturers: Hilleberg, Tarptent, light ultralight tents

PU tents: apply a new PU layer

The original tape on the inside of the seams comes loose after a few years. If the seams have started to leak:

  1. Clean the seams — remove loose remnants of old tape with careful scraping
  2. Dry the tent completely — pitch it in dry weather and leave it standing for a couple of days
  3. Apply PU sealing agent from a tube — products such as Gear Aid Seam Grip WP, McNett, Coghlan’s Seam Sealer
  4. Spread a thin layer along the whole seam on the inside, evenly, with a fingertip or a small brush
  5. Let it cure for 24 hours before packing the tent

Films such as Gear Aid’s video show the process in detail.

SIL tents: apply a silicone solution

Silicone sealing works completely differently — silicone cannot be “glued” on; it must be applied to the outside and evaporates into the fibres.

Home-made silicone solution

  1. Mix 1 part silicone sealant (clear) with 5–10 parts white spirit in a bowl
  2. Stir thoroughly until the silicone dissolves completely in the white spirit
  3. Brush a thin layer onto the outside of the seams — let the silicone solution soak into the fabric
  4. Let it cure for 24–48 hours in a well-ventilated area — the white spirit evaporates, the silicone cures
  5. Test with water before your next trip

Tarptent has a good video showing the technique.

Ready-made products

  • Gear Aid Sil Net — pre-mixed silicone for sil tents
  • MSR Silnet — equivalent
  • Eclipse SIL-Tite — for larger areas

Use in the same way as the home-made solution.

When you need to do it

  • The seam drips when you hose down the tent or stand out in the rain
  • Tape remnants come loose visibly from the inside
  • After many years of use (5+ years) — preventive maintenance
  • After carpet washing — particularly if you have washed it with an unsuitable detergent that has removed the original sealing

Preventive maintenance

Check the tent seams once a year (ideally early in spring, before the first camping trip):

  • Pitch the tent
  • Spray the water on the outside with a hose or shower
  • Check for ingress on the inside along the seams
  • Mark any drip points with tape
  • Seal them after the check

Back to Repair → · Tears and holes in tent fabric and hammock → · Gluing holes and tears in tent fabric → · Tents →

Text: Lars Peters and Snuitide (2022), revised 2026.

Video resources: Gear Aid — PU seam sealing · Tarptent — silicone seam sealing