Waterproof and breathable tents have probably been the most significant advance in camping accessories in the last century. Its main component is the internal membrane, responsible for its characteristics.
In this article, we will explain what type of membranes and garments that carry them we can usually find, and how they work. You will also get to know the tricks on how you check if your tent is waterproof.
Although it is a long and somewhat technical explanation, we recommend reading it. That way, you will quickly understand some issues that we usually misinterpret. You will understand what we mean by reading this section.
So what are you waiting for? Let’s dive in.
What is a Waterproof Tent? Is Your Tent Waterproof?
We go into parts. What does waterproof mean? That it is impenetrable for water during the most severe climatic conditions or in the most demanding uses. In addition to a particular fabric, waterproof clothing must have a specific type of construction that prevents water entry. All seams must be sealed and have effective closure systems in critical areas.
Another different category is water resistance. Attentive! Garments nominated as water-resistant are not waterproof. They offer some type of protection during light rains. But they will not be valid if the rain is heavy. Also, if the garment is subjected to high water pressure, it won’t be waterproof. If the idea is to camp for an extended period in the rain, these tents will not provide adequate protection. You will most likely get wet.
Let’s go ahead. A third concept is that of water repellency. This term refers to a chemical coating that is applied to the outer fabric of tents. These chemical causes water to “slide” down that teardrop instead of being absorbed. These films are known as DWR (Durable Water Repellency). They are not in themselves an adequate method of waterproofing. Yes, when they are combined with waterproof fabrics, they are good enough!
How Do You Check If Your Tent Is Waterproof?
There is no unified standard in the outdoor industry that allows us to get to know it. But there are specific indicators. Let’s see them.
Measurement of Water Resistance
The tests are carried out under the European standard ISO 811: 1981 (Textile fabrics – Determination of resistance to water penetration – Hydrostatic pressure test). There it is specified how to perform a tissue water resistance test in the laboratory.
To measure the fabric’s resistance, devices are used that measure what is called a “water column.” A flat and tense fabric is placed, without anything rubbing under or over it. A 1×1 square tube is placed on top. The tube is filled with water, which increases the pressure until finally, the liquid ends up passing the tissue.
The measurement at the moment when the water begins to penetrate the fabric indicates its impermeability. The impermeability is measured in mm.
Is It Waterproof Enough Garments?
According to international standards, a fabric that supports a minimum of 1500 mm of Water Column is waterproof. Tents with a water column less than this number could withstand light rain for a short time but are not waterproof.
We will look in your technical data sheet for the measurement in millimeters of your water column.
|Less than 600 mm||Not recommended for use in the rain|
|From 600 to 1000 mm||Resistance to light and short rains|
|From 1000 to 2000 mm||Resistance to normal rains for not very long periods|
|From 2000 to 3000 mm||Good resistance to storms or rains for several days|
|From 3000 to 6000 mm||Recommended for more extreme situations|
|6,000mm-10,000mm||Light to moderate rain, moderate snow|
|11,000-15,000mm||Moderate to heavy rain, heavy snow|
|16,000-20,000mm||Heavy to hefty rain, heavy snowstorms|
|More than 20,000mm||Extreme protection|
These are figures that are generally considered acceptable as useful for a tent. However, in other areas, we will hear that something is waterproof from 2,500mm of the water column.
Waterproofing In Real Conditions
There are several reasons.
- The first has a lot to do with pressure. We have seen that the test measures the height of the water contained in the column. That is to say, the water pressure rises as we add water until it passes the textile. Therefore, the pressures on the membrane cause that with less water, it penetrates. Thus, in strong winds, the impermeability drops.
- But the most significant increase in pressure is caused by rubbing, and the loss can be noticeable. Due to all the factors, the laboratory-measured water resistance is increased for safe use in the field.
- Another aspect is the temporary exhibition. Although, a large part of the water that falls on the tent top slides down. Thanks to the DWR treatment, we will see later, after a few hours the water does its work.
- And finally, wear and tear, stains, etc., damage the properties of the membrane. Now a day, manufacturers make their tents differently. So, after extreme use, they continue to maintain at least 60 percent of their properties. Those tents will still have a water resistance that allows them to be used with ease. These tents are built with high resistance, thinking of compensating for that loss.
We can summarize that, on the ground, the real resistance to water is marked by some factors like-
- The ratio of the water column,
- External pressure / friction,
- exposure time and
- State of the membrane.
Tent’s Water column Only 3,000mm? Enough?
An expedition tent, prepared for the worst storm, can have a water column between 1,200mm and 3,000mm only. Compared to 20,000m-30,000m for a jacket, it’s quite low.
We know, the fact it is counterproductive. But we have to breathe, and in one way or another, there must be air circulation. Also, we can remember what we have said about pressure. A double stretch roof does not withstand friction. So the laboratory water column is very similar to that of the field.
However, a floor withstands pressure against the ground when someone is inside. That is why the water column is usually higher than that of the double roof. Because it receives the humidity through the ground, not directly from the rain.
How to Make a Tent Fabric Waterproof?
The manufacturers announced the waterproofing index on two constituent elements:
- The exterior wall
- The floor.
This index is generally higher for the tent floor than for the flysheet. Impermeability by contact is more difficult to ensure; the tent floor should be even more robust than the flysheet. It must be resistant to splashes, rain, humidity, punctures, and abrasion.
To make a piece of fabric waterproof, the process used is coating. This process consists of coating the surface with a coating to make it permeable to water. Also, this process possibly protects the tent from UV rays. There are several methods:
- Polyurethane (PU) Coating: Applied in thin layers on the fabric. The thicker the layer, the more waterproof the fabric, but the heavier it is. The PU achieves impermeability values (water column) from 800 mm to 10,000 mm.
- Thermoplastic Polyurethane Coating (TPU): This coating offers better wear resistance, better bonding. Therefore, you have more excellent durability than conventional PU coatings.
- Silicone Coating: Generally applied to nylon, silicone is an elastic and durable coating. Silicone penetrates the fabric and modifies its properties. It increases resistance to tearing and UV. It is applied in overlapping layers on the two sides of the fabric. It increases the lifespan of the colors of the tent.
The more waterproof a tent, the heavier it will be, and the less it will be breathable.
How to choose a good waterproof tent?
To choose your tent, you must determine the conditions of use: place, season, altitude, and environment. The waterproofness index is a crucial selection criterion to take into account.
It is impossible to request total waterproofing for a tent.
Depending on weather conditions, heavy rain, storm, thunderstorm, wind, and water pressure increase in the tent. In the field, you will encounter several normal phenomena:
Condensation Inside The Flysheet
Condensation is a natural phenomenon. The humidity in the ambient air condenses and settles inside the wall. When it rains, the air and the earth are saturated with humidity, which favors the appearance of condensation. It is, therefore, possible in rainy weather that small droplets of a waterfall inside the tent.
This phenomenon can become even more critical if there is wind: the water droplets are then vaporized. It is not a problem of waterproofing but condensation. The synthetic fibers of nylon and polyester do not breathe very efficiently, unlike cotton.
The passage of several small drops of water is always possible. It does not constitute a defect in the waterproofing of the tent.
Leaks At The Seams And Zips
Over time, drops can be introduced at the seams and zips. Manufacturers make them waterproof by coating and heat-sealed strips. But it may be necessary to have to re-waterproof them.
Ground Level Humidity
In rainy weather, humidity rises from the ground. Moisture spots are likely to appear on the tent floor. In cold weather, the fabric under your mattress may be damp. It can happen if your mattress is not sufficiently insulated. This thermal convection phenomenon is linked to the temperature difference between the ground and your body temperature.
To limit this phenomenon, you can use an additional footprint to slip under the floor of your tent. This is truer if the ground is soggy, and the waterproofing index of the floor of your tent is low.
To avoid body heat loss, we advise you to opt for an insulated mattress.
You must show some indulgence towards your tent and these situations.
It is essential to choose your tent well. But there is not a single foolproof plan on how do you check if your tent is waterproof. So, it is better to choose the right site to pitch it well. Accept that over time the materials will lose their performance. To limit the phenomenon, you must maintain your tent, put it away correctly, and store it dry.