How To Weatherproof a Tent

I love camping in good weather but there’s something special about lying in your sleeping bag hearing the soft morning rain tapping on your tent.

When that rain makes it through to the inside of my tent I feel less nostalgic. The best way to keep water out of your tent is to make sure no water actually comes into contact with your tent body.

Using a footprint underneath your tent, a tarp overhead and a rainfly should be the basis of your weatherproofing strategy.

Practically though, you’re always going to get some water on your tent fabric and that’s why it’s worth making the effort to weatherproof as best you can.

Wait. Surely if I buy the best four-season tent available I should be protected against the rain? These cold-weather tents should be fine, you only need to think about weatherproofing once they get a bit old.

See also: best lightweight tents for backpacking, if you’re looking to replace that mouldy one in your garage!

How does water get into your tent?

In two ways: Through the fabric and through seams. When we look at the different parts of our tent that need waterproofing we need to cover both of these areas. 

Fabric

To keep water from coming through the fabric of the tent we need to block it from the outside and inside. Your DWR coating on the outside of the fabric makes sure the water beads off rather than soaking into the fabric.

The silicone treatment or urethane coating on the inside of the fabric blocks any moisture that made it past the DWR coating. Both of these coatings need to be refreshed from time to time.

Seams

Your seams may be taped but that’s often not enough. We want to make sure the taping is still in good condition and then apply a seam sealer to seal of any tiny stitching holes where moisture would otherwise seep through.

Which parts of the tent need to be weatherproofed?

Tarp

Your first line of defence needs DWR coating on outside and urethane coating underneath. If it has any seams these need to be sealed too.

Rainfly

Even if you’re using a tarp overhead, your rainfly will keep out anything the tarp doesn’t. It needs DWR coating on outside and urethane coating underneath. The seams will need sealing too.

Tent Body / Walls

Solid panels (not vents) need DWR coating on outside and urethane coating on inside. All seams, especially those where the floor meets the wall panels, need sealing.

Floor

Moisture can seep through from wet ground or vegetation under the floor. It’s always best to use a waterproof footprint or tarp under your tent floor but you don’t want to rely on that alone.

If you get any water flowing along the ground that gets in between the tarp and your floor you want to be able to keep that out too. The urethane coating on both sides of the floor needs to be in good shape to keep moisture out.

Read more: how to get a good night’s sleep in a tent.

How to waterproof a tent

Before you start, clean your tent. You need to make sure that the surfaces you’ll be applying the weatherproof coating to are completely clean and dry.

If the fabric is dirty you’ll just be coating a layer of dirt with the weatherproof coating and it’ll come right off in the first bit of rain you get.

It’s a good habit to clean your tent regularly even if you’re not preparing it to weatherproof it. Just don’t use anything abrasive like a scrubbing brush and only use mild detergent, if any, to avoid removing the waterproof coating.

Also, make sure it’s completely dry before packing your tent away. If it’s damp when you put it away you’ll end up with mildew and that also eats away at the waterproof coating.

Sealing tent seams

Inspect your seams for any signs of damage. If a seam is coming apart it’ll need repairing. The taping will eventually start to come away in certain areas.

If you have loose bits of tape, cut these bits off while leaving the intact tape in place. Clean the seams well using a rag and some rubbing alcohol.

Now we want to apply the seam sealer but it’s important to choose the right one according to the coating on the fabric.

Your tent fabric will either have a polyurethane coating (most common) or be made from a silicone treated fabric (Silnylon). Polyurethane will not stick to silicone so it’s important to choose the right product.

Once you’ve cleaned the seams and removed any loose bits, lay it inside-out in the sun in a well ventilated area.

Follow the instructions that come with the seam sealer you bought and apply it evenly along each seam. Once you’re done, make sure to let it dry properly before packing the tent away.

How often should I seam seal my tent?

If you’ve used a flexible, good quality seam seal then it should last a long time. You only really need to re-seal the seams if you see it start flaking off or if you’re starting to get some leaks again.

What’s the best tent seam sealer?

The best urethane seam sealer is Seam Grip WP from Gear Aid. It bonds to just about anything and forms a durable rubber seal that flexes. The tube and brush attachment make it easy to apply to your seams.

If you’ve got a silicone treated tent then your best option is the Seam Grip FC also supplied by Gear Aid. We like that it cures in just 2 hours and offers much better coverage than the other silicone seam sealer Gear Aid offer.

Refreshing the silicone and urethane coating

If you notice any flaking on the floor or inside of your rainfly then it may be time to refresh the silicone or urethane coating.

You’ll need a sponge with a slightly abrasive surface and some rubbing alcohol to clean of the flaky coating.

You want to do this outside in the sun where it’ll dry quickly and you won’t be breathing any fumes in when you coat it.

Once you’ve got it clean, follow the directions on the sealant and apply a thin layer over the entire area.

It’ll probably need up to 24 hours to dry properly before you can pack it away. Remember, this coating is just applied to the inside of the fabric.

While most tents use a polyurethane coating some are treated with a silicone coating. Make sure you use the product that matches the coating your tent was originally treated with by the manufacturer.

What’s the best tent fabric sealant?

The best tent fabric sealant for polyurethane treated fabrics is the Gear Aid Seam Grip + TF Tent Fabric Sealant. One 4oz bottle will be enough to apply a single coat to around 85 square feet of fabric. It cures in about 4 hours but it’s probably a better idea to give it a few hours more.

Refreshing the silicone treatment of a tent made from Silnylon is a bit trickier.

There don’t seem to be many off the shelf options but you can make your own with some regular silicone sealer thinned out with some low odor mineral spirits.

There’s a good explanation of how to do this here. It’s probably best to check with the manufacturer of your tent first.

You might also like: how to stay warm in a tent in winter.

Refreshing the DWR on a tent

If you spray water onto the outside of your tent and it doesn’t bead off right away then you may need to refresh the DWR coating.

Make sure your tent is clean before applying the DWR coating spray. If you’ve just given it a wash you can go ahead and apply the DWR spray without having to wait for the tent to be dry.

Follow the directions that came with the product and spray an even layer over the exterior of the rainfly. Give it a few minutes and then wipe off excess coating using a damp cloth.

What’s the best waterproofing spray?

The best DWR coating for tents is the Nikwax Tent and Gear Solarproof spray. It’s easy to use and, in addition to being a great water repellent, gives your tent good UV protection too.

If you prefer an aerosol silicone based spray then the Kiwi Camp Dry heavy duty water repellent is an excellent option. It needs to be applied to a dry surface though.

Tent Weatherproofing Checklist – Step By Step

Here’s a quick checklist of the steps you need to follow to weatherproof your tent:

  • Clean areas well – Wash the external surfaces with soap and water and internal surfaces and seams with rubbing alcohol (isopropyl alcohol).
  • Make sure it’s dry – Seams and internal surfaces must be dry before applying coating. If you’re applying a water based DWR coating to the external surfaces they don’t need to be completely dry. 
  • Fix any damage – Puncture holes in your floor, rips in walls or seam stitching that has come apart all need to be fixed before applying coatings. Loose seam tape needs to be trimmed and removed.
  • Identify areas that need attention – Are you coating and sealing everything or just that one spot or seam that keeps leaking?
  • Buy the right product – Is your tent made from silicone treated fabric or does it have a polyurethane coating? You need to know before buying either a polyurethane or silicone based product.
  • Which side of the fabric are you treating? – Internal surfaces are treated by either polyurethane or silicone coatings while external surfaces need a DWR coating.
  • Choose a good spot – Lay the tent fabric out on a surface that won’t damage it. You’re going to be crawling around on it on your knees. Your garage floor will probably result in micro-punctures so rather head out to your lawn.
  • Read the instructions – Follow the instructions that come with the product. Especially with regard to coverage and curing or drying times.
  • Let it dry – Once you’ve sealed, coated or sprayed make sure you let it cure for longer than it says you should before packing the tent up.

Why does a tent need weather proofing?

That tent you bought wasn’t cheap and the guy at the store said it was completely waterproof so why would you need to weatherproof it any more?

A lot of tents have seams that are taped but not sealed. If you really want to keep all moisture out you need to seal those seams.

Also, coatings on the inside and outside of the tent eventually wear off and will need to be refreshed if you want to keep the rain out.

What if the wall leaks?

A leaky tent wall is either cause by damage to the fabric, leaking seams, degraded PU coating or degraded DWR coating.

If you can’t see any obvious damage then set the tent up and spray some water on it. Does the water bead off? If not then you’ll need to refresh the DWR coating.

Have someone spray water on the tent while you’re inside it and have a careful look at all of the seams.

If you see any flakiness or tape coming away it may be time to reseal the seams. The seams along where the floor meets the walls are often your most likely culprits.

What if the floor leaks?

Firstly, are you using a groundsheet? You should be. Inspect your floor for any obvious damage and repair it.

Even tiny little punctures can eventually let a fair amount of water in.

Besides obvious holes, if you’re seeing some flakiness on your floor then it may be time to refresh the floor coating. Coating it on both sides will give you the best protection.

Factors that affect a tent’s waterproofness

Here are a few of the main factors that will determine how waterproof your tent is:

  • Fabric – Different fabrics (cotton canvas, polyester, polyester-cotton, nylon, etc…) have different waterproof properties but these can all be managed by coatings. Your choice in fabric is more likely to be influenced by weight, durability and cost.
  • Thread count – The higher the density of the threads, the more waterproof it’ll be.
  • Coating – A good coating is one of the biggest factors in keeping water out. You get what you pay for. Cheap acrylic coatings won’t last for long while polyurethane or more expensive silicone coatings will perform better.
  • Seams – The quality of the stitching in the seams, taping and sealing will all determine whether moisture will come in through the spots where the floor meets the walls or not. Cheaper tents have less stitches per inch and will be more likely to let moisture through.
  • Location – Pitching your tent in the wrong spot like at the bottom of a slope or in a depression will probably test your tent’s weatherproof ability to breaking point.
  • Footprint and tarp – Using a footprint and a good waterproof tarp or fly will give your tent a better chance of keeping you dry inside.

Just remember that water can come from within your tent too. A PVC coated tent will keep any rain out but will build up condensation from your breath.

Tips for waterproofing an old tent

Even if your old tent wasn’t very waterproof to begin with, you may not have to replace it just yet.

If you clean it thoroughly and patch any damage you could still waterproof it fairly well. If it’s an old tent then it probably doesn’t have sealed seams.

Sealing each seam with a good tent seam sealer will help even if the stitching has become a little looser with age.

Even if you’re going to use a tarp it’s a good idea to coat the floor on both sides with a urethane coating.

Once you’ve done that you can give the entire external exposed surface of the tent a spray with a good DWR.

What’s your tent made of?

The material your tent is made from will also determine the products or techniques you use to weatherproof it. 

Tents made from polycotton, polyester or nylon normally have a very tight weave that will already present a little water resistance.

These fibres also don’t absorb water like cotton does. The fabric will normally be coated with a polyurethane coating or will have a silicone treatment impregnated into the fabric.

Cotton canvas – A new canvas tent will almost always leak the first time you use it in the rain. New cotton canvas tents need to “weather” before becoming waterproof.

The easiest way to do this is to set it up and then spray it down with some water. Once they get wet the cotton fibers swell to form a tighter knit fabric. When they dry the fibers stay in place and you now have a waterproof tent.

It may take a 2 or 3 exposures to water before it gives you complete protection. Spraying a DWR coating on the outside of the canvas will help.

What Is The Tent PU Rating?

When manufacturers describe how waterproof their tents are they will quote a figure in mm. This is either referred to as the PU rating or HH (Hydrostatic Head) rating.

The PU stands for polyurethane as that’s the coating most often applied to waterproof tent fabrics.

This figure refers to how high a column of water you could have stand on the fabric for a minute before it starts to seep through.

The higher the figure, the more waterproof the fabric is. Most tents are in the 1,500 to 3,000mm range.

Anything above 800mm is considered “waterproof” but remember that this figure tells you nothing about how waterproof the seams of the tent are.

What does factory-taped seals mean?

If your tent is “factory taped” it means that the manufacturer has run a strip of tape along the stitching of the seams.

The quality of the taping varies but it’ll certainly help to keep the water out somewhat. To be properly waterproof they will need sealing.

The tape eventually comes away and, even when it’s brand new, really isn’t enough to stop all moisture from seeping through the stitches.

Do I need to waterproof a new tent?

Probably not. If you’ve bought a good tent then the rainfly, tent body and floor probably are already coated. If the seams are only taped then it’s worth sealing them yourself to be extra sure. 

If you’ve bought a cheap tent then the waterproof coating is probably really thin. In that case it’s worth recoating the inside of the rainfly and floor with a PU coating and treating the outside of the rainfly with a DWR spray.

Can you buy a cheap tent and treat it to be waterproof?

You could but is the effort really worth it?

How much money are you actually saving? Remember, while you can apply extra coatings or DWR to the fabric, there’s not much you can do about weak stitching on the seams or the durability of the fabric.

Once they give way, and they will, you’re going to get wet.

Caring For Your Tent

Taking good care of your tent won’t only make it last longer structurally, it’ll make your waterproofing efforts last longer too. Here are a few tent care tips:

  • Clean it thoroughly after use but never machine wash
  • Make sure it’s completely dry before folding up
  • Store it in a dry place, out of sunlight

When should you just get a new tent?

Eventually bumps, scrapes and UV exposure will take their toll on your tent. Once you start getting split seams, tears and threadbare fabric you’re beyond waterproofing.

You’ll need to replace your tent.

However, just because a tent leaks doesn’t mean it needs replacing. Identify where it’s leaking and, if it’s not from damage, refreshing the waterproof coating may be all it needs.

Wrapping Up

If you camp regularly then at some point it’s inevitable that you’re going to get caught out by some lousy weather.

Applying common sense when setting up your tent, using a tarp and a good rainfly will go a long way to keeping you dry.

If you apply our tips on how to weatherproof a tent before you head out then you’ll be even more likely to stay dry when it starts to get wet and wild outside.

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