Kersplat! The first fat drop splashed against my forehead with a sound usually reserved for cartoons. But there it was, bigger than life, a breach in the outer defenses of my new tent. The rainfly eventually sprung leaks in seven spots, showering my sleeping bag and gear. Cursing myself for doing such a poor seam-sealing job, I pulled a jacket over my head and prayed for a sunny morning.
My sloppy sealing only cost me a soggy night in the high peaks region of northern Connecticut, but what if I'd been in the midst of a long-awaited trip to Alaska, or more important, a romantic night in the woods? Or say the temperature suddenly plunged and turned my leaky tent into an icebox? That's a potentially lethal predicament when you're way out in a remote location.
Tents of all types and ages require some weatherproofing. New models require seam sealing, year-old rainflies get punctured and need patches, and well-worn floors need fresh waterproof coatings. Even expensive four-season shelters develop cracks in their armor, which is why every tent owner should set aside an hour or so each spring for some simple preventive maintenance.
Step 1: Decide which seams to seal. Not every seam on the tent needs to be waterproof, only those that will be exposed to rain, runoff, or puddles. This always includes seams on the fly and tent floor, but usually not on the tent canopy. Because seams on the interior walls border porous panels of mesh and uncoated nylon, treatment of these seams offers little additional protection, so don't waste your time.
Many new tents come with factory-taped floor and fly seams, which is a big plus. A simple visual check will reveal if your seams are taped. They'll have a smooth feel and glossy appearance, as if someone ironed a thin strip of translucent packing tape over the threads. Taped seams don't require additional waterproofing.
Untaped exposed seams, on the other hand, have thousands of tiny needle holes that are prone to leaking. You'll need a tube of seam sealer, a polyurethane glue that seeps into every crevice and forms a watertight barrier as it dries. Three goods ones: McNett Outdoor's Seam Grip, Kenyon's Seam Sealer, and Aquaseal's Seam Seal in a bottle with a built-in applicator. All are commonly available at most outdoor shops. Even tents with taped floor and fly seams usually need some seam sealing, particularly along zippers and around corners. Under normal conditions, a tent needs a treatment every three to four years.
Step 2: Determine which side of the fabric to seal. Before you slather on any sealant, carefully read the instructions to determine which side of the seam to treat. Some sealants always go on the inside surface of the rainfly and tent floor, while others should go on the side opposite the original waterproof coating. To find the original coating, look for the surface that has the shinier finish or sprinkle water on both sides. The coated side usually beads up and the uncoated side tends to puddle.
Step 3: Prepare the seams. With a toothbrush, remove any peeling remnants of old sealant, then swab the seams clean with a rag dipped in isopropyl alcohol. Allow a few minutes for seams to dry, then pitch the tent in a well-ventilated location and attach the rainfly with the surface to be coated facing out. Cinching the fly tight will stretch the seams and allow for better sealant penetration and for faster drying time. To get at hard-to-reach places on your tent floor, turn it inside out if necessary.
Step 4: With long, even strokes, apply a generous coat of seam sealant over each of your chosen seams. Wait one hour for the sealant to dry, then repeat the procedure to cover any gaps.
Step 5: Once the seam goop dries completely, set the tent under a sprinkler for several hours to check for leaks. Let it dry thoroughly again and reapply seam sealant if necessary.
Repeated encounters with sticks, stones, pocketknives, and boot heels can open gaping holes in your tent. To mend large rips and torn seams, consult a professional repair shop and avoid duct tape. It'll leak and leave a sticky residue that will complicate permanent repair.
To repair dime-size or smaller punctures, use a standard tent or sleeping pad repair kit and the "Hot Pot Method." Cut a swatch of waterproof nylon about a half inch wider than the hole, and apply contact cement around the wound. Affix the patch, then place a flat-bottomed pot of boiling water on top. It helps to have a board or book underneath the tent so there's a good, flat surface. In about 30 minutes, you'll have a permanent, heat-sealed bond.
Refreshing The Coating
With prolonged exposure to sun, sand, wind, and rain, a tent's water repellent coating will gradually wear thin or delaminate, leaving vulnerable areas. If you've noticed mysterious trickles or persistent seeping beneath your sleeping pad, visit your local camping store and invest a few dollars in a waterproof treatment like Aquaseal's Poly Coat or Kenyon's Recoat.
The new coat of gunk typically goes on the surface that's opposite the original coat. (Look for a shiny finish or signs of delaminating polyurethane to confirm the location of the original coat.) Give the uncoated side a sponge bath, let it dry, then spread the formula from corner to corner with a clean rag. This type of treatment smells awful and takes two or three days to cure, so it helps to have a garage or sheltered porch. The finished fly and floor may also feel a bit tacky once they dry, but that's easily remedied with a dusting of talcum powder.