When buyers compare tents, they usually look at capacity, weight and price first. But the component that most decides how a tent actually performs over its lifetime is something most spec sheets barely mention: the coating on the flysheet fabric. Here is a practical comparison from the factory floor.
What a coating actually does
Woven polyester and nylon fabrics are not waterproof by themselves — water passes through the weave. A coating is applied to the inner face of the fabric to provide the waterproof barrier (measured as hydrostatic head, in millimetres), and it also influences UV resistance, tear strength, pack weight and, of course, unit cost.
PU coating — the workhorse
Polyurethane is the most widely used coating in the industry, and for good reason. It is cost-effective, bonds well to both polyester and nylon, and delivers reliable waterproofing in the 2,000–5,000 mm range that covers most family and trekking applications. Most of our standard 190T/210T polyester flysheets use PU coatings between 2,000 and 5,000 mm.
Its weaknesses: PU adds more weight per layer than silicone, and it slowly hydrolyses — the coating breaks down over the years, especially when tents are stored damp. That is why proper drying before storage matters so much for PU-coated tents.
Silicone — the performance choice
Silicone elastomer is impregnated into the fabric rather than layered on top of it (the classic “silnylon” and “silpoly”). It boosts tear strength significantly — often two to three times — because the silicone keeps yarns from sliding across each other. It also resists UV far better than PU and keeps weight low, which is why it dominates the ultralight segment.
Trade-offs: silicone-coated fabric cannot be seam-taped with standard machines, so seams are sealed with liquid sealant instead. It is also more expensive. Many premium tents — including our 75D nylon models — use a sil/PU hybrid: silicone on the inside for strength, PU on the outside so the seams can still be taped. You get most of both worlds.
TPU — the premium all-rounder
Thermoplastic polyurethane is applied as a film. It is extremely abrasion-resistant, stays flexible in freezing temperatures and tolerates repeated folding very well. That makes it ideal for high-wear applications — premium floors, snow skirts, and tents built for daily commercial use such as rental fleets. It is the most expensive of the three, so it appears on flagship products rather than entry-level lines.
Hydrostatic head, explained
The waterproof rating of a coated fabric is its hydrostatic head (HH) — the height of a water column the fabric resists before leaking.
| Hydrostatic head | Real-world meaning | Typical use |
|---|---|---|
| 1,500 mm | Light rain, short exposure | Budget shelters, beach tents |
| 2,000–3,000 mm | Reliable for family camping | Entry and mid-range family tents |
| 3,000–5,000 mm | Extended rain, three-season use | Premium family and trekking tents |
| 5,000 mm+ | Standing water, ground pressure | Floors and expedition-grade gear |
Note that our 150D Oxford floor fabrics run 5,000–10,000 mm — floors need it, because your body weight presses the fabric into any ground moisture.
Which coating for which product?
- Budget family line: 190T polyester + PU 2,000 mm — the best cost-to-performance ratio for volume retail.
- Premium family line: 210T polyester + PU 3,000–5,000 mm, taped seams.
- Ultralight / backpacking: 75D nylon with sil/PU hybrid — strength at low weight.
- Glamping / commercial: cotton-blend fabrics for breathability and quietness, with heavy coated floors.
Frequently asked questions
Is a higher hydrostatic head always better?
No. Beyond about 3,000 mm on a flysheet you hit diminishing returns — weight and cost keep rising while real-world benefit shrinks. A well-made 3,000 mm tent with properly taped seams outperforms a badly made 5,000 mm one every time.
Can coatings be combined?
Yes — the sil/PU hybrid described above is the standard answer, and it is what we use on our 75D nylon flysheets.
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