Nortent Waterproof Tents

Unraveling the Compleixities of Tent Waterproofing

Written by: Tom Crew



Time to read 6 min

When it comes to choosing the perfect tent for your outdoor adventures, understanding the intricate world of waterproofing is essential. Manufacturers employ various techniques and measurements to ensure their tents can withstand the elements, but deciphering this information can be a daunting task. In this comprehensive guide, we will explore the key aspects of tent waterproofing, including industry-standard measurements, innovative coatings, and practical examples to help you make informed decisions.

Key Waterproofing Techniques

Before diving into specific coatings, it's important to understand the popular waterproofing techniques used in the industry:

  1. Polyurethane (PU) Coating : This is a traditional method where a layer of polyurethane is applied to the fabric. It is cost-effective and provides a high level of water resistance. PU coatings are commonly found in budget and mid-range tents.

  2. Silicone Treatment : Silicone treatments involve impregnating the fabric with silicone, enhancing its waterproof properties and durability. Known as silnylon, silicone-treated fabrics offer superior resistance to UV degradation and maintain flexibility, making them ideal for high-performance tents.

  3. Dual Coating : Some manufacturers combine PU and silicone coatings to leverage the benefits of both materials. This dual approach provides excellent waterproofing and enhanced durability, typically found in higher-end models.

  4. Silpoly : This is a polyester fabric coated with silicone, offering less stretch and sagging compared to nylon, especially when wet. Silpoly is gaining popularity for its stability and durability in harsh weather conditions.

  5. Nanotechnology Coatings : Utilizing nanoparticles, these advanced coatings provide a thinner yet more effective waterproof barrier. Nanotechnology coatings offer enhanced breathability while maintaining high levels of water resistance.

  6. Eco-Friendly Coatings : With growing concerns about sustainability, manufacturers are developing eco-friendly waterproof coatings that minimise environmental impact. These coatings avoid harmful chemicals while still providing effective water resistance.

PU (Polyurethane) Coating

When a tent is described as PU5000 mm, it indicates that the material has a Polyurethane coating enhancing its waterproofness. The "5000 mm" specifies the tent's waterproof rating, denoting its capacity to endure a water column of 5000 millimeters in height without leakage. Essentially, the fabric can resist the pressure of water up to 5 meters high before seeping occurs.

PU Coating Details :

  • Durability : PU coatings provide a reliable level of water resistance but can degrade over time, especially with frequent use and exposure to UV light.
  • Maintenance : Regular reproofing can extend the life of PU-coated fabrics, ensuring they remain waterproof.
  • Application : PU coatings are often used on tent floors due to their ability to handle ground moisture and pressure.

HH (Hydrostatic Head)

The "hydrostatic head" (HH) measurement is a critical indicator of a fabric's waterproofness, representing the height of a water column that the fabric can withstand before water begins to penetrate. For instance, our tents feature PU (Polyurethane) coatings primarily on the floor, which requires high water resistance due to direct contact with the ground and the pressure exerted by occupants.

In contrast, the flysheet, or the tent's outer layer, is made from silicone-treated nylon. Unlike a simple surface layer, the silicone treatment permeates and bonds with the fabric, significantly enhancing its waterproofness while maintaining its flexibility and durability.

A Hydrostatic Head rating of 3000 mm for a flysheet means the fabric can resist a water column up to 3000 millimeters tall before leaking. We specifically use the HH term for silicone-treated nylon, commonly known as silnylon. Conversely, a PU4000 mm label indicates a Polyurethane-coated fabric that can withstand a 4000 mm tall water column.

Understanding these PU and HH ratings is essential for evaluating the waterproof capabilities of tent materials, ensuring that campers choose the right tent for their needs and conditions.

Silicone-Treated Fabrics

Silicone treatments are far more enduring, preserving their waterproof quality over many more years. This longevity makes high Hydrostatic Head (HH) numbers less critical compared to PU coatings. A 3000 mm silicone-coated fabric can outperform a 5000 mm PU-coated material over time due to PU's decreasing efficacy.

Silicone Treatment Details :

  • Measurement and Ratings : The effectiveness of silicone-treated fabrics is measured similarly to PU, with HH ratings indicating the water column height the fabric can withstand. An HH rating of 3000 mm means the fabric can resist a 3000 mm tall water column before leaking.
  • Durability : Silicone treatments maintain their waterproof properties longer than PU, making them ideal for high-stress areas like the flysheet.
  • Application : Silicone-treated fabrics are often used for flysheets and outer layers due to their superior UV resistance and flexibility.
  • Polycotton Fabric : Our polycotton fabric, for instance, has a modest HH rating of 700 mm. The waterproofing is inherent in the fibers, maintaining consistent performance over the years without the need for reproofing.

Longevity of Waterproof Coatings

PU coatings, while initially providing high hydrostatic head values, tend to degrade over time. This degradation is why tents with PU coatings often start with a high HH rating to ensure prolonged waterproofness, even though a lower HH rating of around 500-600 mm is generally sufficient for most weather conditions. This concept also applies to waterproof jackets, which might start with an HH rating of 15,000-20,000 mm to counteract the expected decline over time.

Polyurethane (PU) coatings can significantly reduce a fabric's tear strength, potentially weakening it by up to 75%. This is why we avoid using PU coatings on our flysheets. To offset PU's weakening effect, a much thicker fabric would be necessary, which would add undesirable weight to the tent. Instead, we prefer more durable and lightweight alternatives like silicone-treated fabrics, which offer longevity without compromising strength or increasing weight.

Factors Affecting Waterproof Coating Longevity

The longevity of a fabric's waterproof coating is influenced by various factors that can lead to a decrease in its hydrostatic head rating over time. These factors include:

Wear and Tear: The repeated use and folding of a tent can cause micro-abrasions on the surface of the coated fabric, gradually wearing away the coating and reducing its ability to repel water effectively.

UV Exposure: Prolonged exposure to ultraviolet (UV) light can have a detrimental effect on the waterproof coatings of fabrics. The UV radiation can break down the chemical bonds within the coating, leading to a loss of waterproofness over time.

Dirt and Oils: The accumulation of dirt, oils, and other substances on the surface of the fabric can clog the pores of the coating or create a layer over it, hindering its effectiveness in repelling water.

Chemical Damage: Exposure to harsh chemicals, whether from the environment or from cleaning agents, can cause significant damage to the coating on a fabric. It is crucial to use only specifically designed cleaning products that are safe for waterproof materials, as certain detergents and solvents can be particularly harmful.

Hydrolysis: In the presence of moisture and heat, a chemical process called hydrolysis can occur, leading to the decomposition of the waterproof coating. Some coatings, such as PU (polyurethane), are more susceptible to hydrolysis than others, which can result in a reduction of the hydrostatic head over time.

Flexing and Stretching: The physical stress caused by the repeated flexing and stretching of the fabric can weaken the bond between the fabric and its coating. Over time, this stress can lead to the development of cracks and peeling, allowing water to penetrate through the fabric.

Production Quality: The initial quality and application of the coating during the manufacturing process play a significant role in its longevity. Any imperfections or inconsistencies in the coating process can create areas that are more prone to degradation, which may not become apparent until the fabric has been in use for some time.


Understanding the complexities of tent waterproofing is crucial for making informed decisions when selecting gear for your outdoor adventures. By familiarising yourself with the various waterproofing techniques, ratings, and measurements, you can choose a tent that will keep you dry and comfortable in any weather condition. Additionally, considering factors such as wear and tear, UV exposure, and proper maintenance will help extend the longevity of your tent's waterproof coating.

When it comes to reliable and innovative tent options, Nortent stands out as a top choice. With their commitment to unmatched quality, cutting-edge design, and sustainability, Nortent tents are engineered to perform in the most demanding environments. By investing in a Nortent tent, you can embark on your outdoor adventures with confidence, knowing that you have a shelter built to withstand the elements.

Why Choose Nortent?

Unmatched Quality: Nortent tents are built to withstand the harshest conditions, ensuring your comfort and safety in any environment.

Innovative Design:  From the aerodynamic shapes to the quick-setup systems, Nortent gear is at the forefront of outdoor innovation.

Sustainability Commitment:Embracing eco-friendly practices, Nortent is dedicated to preserving the natural beauty of our landscapes for future generations.