Guide to tent fabrics and waterproofing


Make sure you know what you are looking for when buying a tent.

Rating waterproofness

First, let’s look at how waterproofness (or hydrostatic head) is measured. It is rated according to two tests and this is the same for all waterproof fabrics, such as those used for jackets and tents.

Test one is simulated rainfall, during which a fabric will be placed in a room where it rains. The fabric is rated according to the amount of time and pressure of the rainfall.

Test two is the Static Column Water Resistance Test. A column of water is placed on top of a fabric and the level at which the water begins to seep through is recorded. These results are measured in mm.

Rain on nylon fabricYou will see fabrics rated, for example, 3,000mm, 5,000mm and 10,000m. The higher the figure the more waterproof it is. A very high quality waterproof fabric may score between 15,000mm and 30,000mm but it’s important to take into account breathability as well.

Rating breathability

Breathability is measured over a 24-hour period by the rate at which water vapour passes through a fabric. This result is scored in grams of water vapour per square meter (g/m2) or just “g”.

A higher level of breathability will give a higher “g” rate. Standard fabrics are around 5,000g.

Taped seams

Seams of jacket and tents need to be attached together. These can mean stitching or glueing. In addition, seams may have taping for extra waterproofing.

Durable Water Repellent (DWR) coatings are applied to many jackets and tents to help with the dispersion of water. You’ll see water bead up and roll off the surface if it has been treated with DWR. To rewaterproof items see our previous feature, How to re-waterproof a jacket

Gore product being tested in a rain room.

Gore product being tested in a rain room.

A note about Gore-Tex

Gore-Tex is both waterproof and breathable but it is not measured in the standard mm. It is reckoned to be comparable to a waterproof fabric rated at 20,000mm to 60,000mm.

Tent fabrics

Modern tents are made from several different fabrics, including coated polyester, coated nylon and cuben fiber.

Nylon is stronger and more resistant to abrasion than polyester. But both fabrics require a coating to become waterproof.

A fabric’s denier “D” is a rough indicator of its weight per square area. The lightest tent fabrics are 10D while a tent floor might be made of 70D.

Tent fabric coatings

Polyurethane (PU) is the most common coating for tents, especially budget tents. It’s the cheapest way to achieve a waterproof fabric with a fair amount of durability in wet conditions.

Unfortunately, PU coatings can be susceptible to hydrolysis (chemical breakup) due to the weather and sun. This renders them non-waterproof over time.

More expensive tents may have the addition of polyether in the PU formulations, which makes them highly resistant to hydrolysis.

Silicone elastomer coated nylons (or SilNylon) are used on many higher quality tents. SilNylon is very water repellent, elastic and stable in all UV and temperature conditions. SilNylon is also stronger, lighter and more robust than PU coated fabrics. Another benefit is that it is a slippery fabric, so snow slides off it easily in winter conditions.

The main drawback of SilNylon tents is cost. Silicone is far pricier than PU and it takes longer to coat the fabric. Another disadvantage is that because the silicone is slippery the seams can’t be taped. The solution that some tent makers have come up with is to use nylon that’s coated with silicone on the outside and PU on the inside – and then the PU is seam taped. It’s worth noting that double-sided silicone coated fabrics are lighter, stronger and more durable than PU/silicone combinations.

Cuben fiber, or non-woven Dyneema (NWD), is the lightest, strongest and most durable waterproof material used in the outdoor industry. In fact, it weighs less than half as much as most SilNylon-made tents. Apparently, Dyneema threads are “50 to 70% lighter and 400%+ stronger than Kevlar and 1,500% stronger than steel per unit weight”. This fabric is then sandwiched between UV resistant Mylar. And unlike SilNylon, cuben fiber doesn’t stretch, which means that you don’t need to retighten a tent’s guylines as frequently.

You’ll either like this or hate it but Dyneema is translucent, so you’ll see the night sky through it.

Although cuben fiber sounds too good to be true there are some disadvantages. It is very costly and it is less heat resistant than nylon so you need to take far more care when cooking inside a tent galley area. The non-stretching qualities can also leave cuben fibre tents more susceptible to tears.

Voice of the expert (or the plot thickens)

Clive Garrett, of OASE Outdoors, which is behind three major tent brands Outwell, Easy Camp and Robens, reports that 1,500mm is widely considered the minimum for UK summer camping, while 3,000mm is a good choice for most seasons and in Scotland.

Clive says: “We would say that 3,000mm should handle everything that the UK could throw at it.”

He adds: “Many manufacturers will use 3,000mm coatings for entry level tents, such as with Outwell.

“However, it’s worth pointing out that if is often not the thickness of the coating that is important but the initial quality of the material. For instance, a 5,000mm coating may be needed to proof a loosely woven base fabric to obtain the same performance as a tighter woven fabric with a thinner coating

“I remember the late Bob Saunders (a leader in early lightweight tent design) telling me the reason he used silicon elastomer coating on his tents was the fact that it is applied cold whereas PU-coatings were applied hot and this immediately degrades a fabric.

“Every additional PU-coating required to up the hydrostatic head damages the fabric more. The greater the hydrostatic head then the better the base fabric must be to handle the process and this ups the production costs and weight.”

Choosing a tent

Much of the decision-making process will be dependent on your budget. It is also important to think about where you will camp (wild or campsite) and at what time of the year.

Spend as much as you can afford on a tent that is lighter or more waterproof. Ask the retailer for an expert to explain all the differences and read reviews on-line.

A tent is a big outlay and it’s important to get it right.

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4 comments on “Guide to tent fabrics and waterproofing
  1. Santiago Castro says:

    Hi, which is best, a waterproof of 5.000 – 10.000 mm or a 1500 mm PU coating, silicone?
    I was searching the features of the north face tadpole 2 and says: \”floor: lightweight nylon ripstop, 1.500mm PU coating, silicone\”. The last part says: \”PU coating, silicone\”… I don´t understand whether the floor is coated in PU or silicone….or both??? I´d appreciate if you help me on this because I´m looking forward to buy a tent.

    • Neil Braidwood says:

      Hi Santiago

      Your question is quite technical, so we have directed it straight to North Face for their experts to answer. We hope to have a response soon.

  2. michael hargadon says:

    hi there i am looking at buying a Cortes Octagon 8 tent is this an all year round tent as i will be using it in heavy torrential rain fall and also in the summer and winter snow. or can you advise me on the best family tent for the same things please.

    thanks i hope you can help

    • Neil Braidwood says:

      Hi Michael

      Thanks for reading this post and leaving a comment. I must say, we haven’t seen the Coleman Cortes in the flesh – and it looks pretty amazing from the pictures we’ve seen. Kind of similar to a yurt. A quick look at the spec though makes this a summer tent – not really suitable for rain or winter use. It has a hydrostatic head of only 2,000mm – one of the lowest we’ve seen on some tents.
      If you like this style of tent – take a look at Nordisk, who make a bell tent that is built for all weathers, or Tentipi, who make teepee style tents which accommodate wood-burning stoves!

1 Pings/Trackbacks for "Guide to tent fabrics and waterproofing"
  1. […] A word about tent waterproofing. Tents are made from different fabrics and coated with a range of waterproofing solutions. To find out more see our guide to tent fabrics and waterproofing. […]


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