Tent Seam Sealer: How to Apply

© Blissy (@blissy_walks)

What is Tent Seam Sealer?

Tent seam sealer is an application, typically tape or glue, that is designed to cover up the leaky seams of a tent.

Tent seams are where the tent fabric is stitched together along the wall and the floor. These seams are notorious for potential leaks during heavy rains, dew, water runoff, etc. Water will seep into a tent through stitching that 1) was never sealed in the first place or 2) has worn out over time. Most companies will waterproof the seams during manufacturing. However, especially with cottage industry gear companies, seam sealing is not standard procedure and might cost extra money for them to do.

Step 1: Make Sure You Need Seam Sealant

If there is no tape on the seams, or the tape is coming off, then you need to consider sealing the seams with an extra layer of sealant for waterproofing. 

A) TAPE: Taping the seams is commonly done during the manufacturing process on most retail tents. It is a thin flexible tape that provides a physical barrier from the rain. Since most tents have their seams taped during the manufacturing process, you usually don't need to tape seal them right out of the box.

You can easily tell if a seam is taped by looking inside the tent. A properly taped tent will have a layer of clear tape integrated into all the seams, both along the walls and the floor of the tent. If there is tape, you're all set and don't have to add any extra waterproofing.

B) SEAM SEALANT: The sealant is a waterproof chemical, like a glue or goo, that absorbs into the tent fabric and repels water. It adheres to a seam and forms a water impermeable barrier. It is physically brushed onto a seam to ensure it penetrates the holes of the stitching.

Step 2: Select Sealant Based on Tent Fabric

Different tent materials and fabrics require different types of seam sealants. Therefore, you need to determine what type of tent fabric you have. If you don't know what material your tent or tarp is, you can always check the manufacturer's website or contact them. 

A) SILICONE COATED FABRICS: Ultralight tents and tarps often use silicone coated fabrics. These need to be sealed with a silicone-based sealant because silicone is the only material that will adhere to the silicone in these fabrics. The most popular silicone sealer is Gear Aid Seam Grip SIL (formerly McNett’s Sil Net), which is both washable and temperature resistant.  

*For your own DIY silicone sealant, mix 100% pure silicone and mineral spirits at a 1:1 ratio. This homemade solution is cheap and can often penetrate seams better than commercial products.

B) POLYURETHANE COATED FABRICS: Similar to the silicone tents, polyurethane coated tent fabrics can only be treated with a urethane-based sealant. A silicone sealant will not work. The top urethane sealants are: 

• Gear Aid Seam Grip FC (formerly Seam Sure). Seam Grip FC is a fast-curing water-based sealant that can dry is as little as two hours. Unless you need a heavy layer of waterproofing, Gear Aid Seam Grip FC is recommended over Seam Grip WP because it is easier to work with. It absorbs into the fabric of the tent and cleans up easily.

• Gear Aid Seam Grip WP (formerly Seam Grip). Seam Grip WP is a thermoset urethane formula that goes on thicker and takes longer to cure. It’s so thick that you can use WP as an adhesive. Because it is so thick, Seam Grip WP requires some extra elbow grease to work the sealant into the fabric.

Coleman and Coghlans also make fast-drying water-based seam sealers that are equipped with applicator pads for easy application. Just tip the bottle and use the built-in applicator to brush on the sealer.

C) DYNEEMA (CUBEN FIBER) FABRIC: In general, Dyneema tents don't need to be seam sealed. If you want that extra protection, you can use the lightweight Gear Aid Seam Grip FC or similar water-based sealer though.

Step 3: Apply the Seam Sealer

PREP: Sealing a leaky tent only requires a handful of supplies, an hour of your time and about a day for drying. Try to find a non-humid day around 50 to 70 degrees (F), where it can dry easily.

Make sure you you cover every seam and seal BOTH the inside and the outside of the seams. This often requires setting up the tent as it would normally stand.

MATERIALS:  You'll need the following supplies before you begin.

• Cloth: for cleaning the existing seams.

• Rubbing Alcohol: for cleaning existing seams.

• Seam Sealer: remember to choose the correct sealer for your tent fabric.

• Brush (maybe): roughly an inch wide for applying the sealant. Some sealants come included with a brush.

HOW TO APPLY:

1. Setup Tent. Set up your tent outside in a dry, sunny spot or brightly lit room so you can see all of the seams. Put the fly on inside out, so the seams are exposed.

2. Remove Any Damaged Sealant Tape. Check for any tape that might be loose or damaged. Gently remove those sections, while trying to leave undamaged parts intact.

3. Clean Seams. Clean ALL your tent seams of dust, dirt and grime. Wipe it down with a cloth and rubbing alcohol. Let it dry.

4. Apply Sealant to Interior Seams. Dip your brush in the sealant mix and apply the new seam sealer to the interior seams. Apply the seam sealer approximately 1/4 inch past the seams on either side of the seam. Wipe off excess as needed.

Do NOT get seam seal on the mesh or zippers. Some people choose to use painter's tape to cover up zippers and other sensitive areas.

5. Apply Sealant to Exterior Seams. Repeat the process for the exterior sides of the seams.

6. Let it Dry. Allow the tent to air dry for 12 to 24 hours. If the sealant is still sticky at 24 hours, talcum powder can be sprinkled on the seams.

7. (Optional) Spray it With Water. Test your job by spraying your tent with a garden hose and examining it for leaks.

More: Waterproofing Tent Tips

• For Leak Prevention: If rain does not bead up on the walls of your tent, then you should consider treating it with a fresh coat of durable water repellent (DWR). This coating is great for treating the exterior of the tent and rainfly. It acts like a waxy coating and prevents water from being absorbed through the walls.

• For Seaping Prevention: Use a groundsheet (tent footprint) underneath your tent to protect it from absorbing water runoff and moisture from the ground. 

• For Hole Prevention: Choose your tent site wisely and clear rocks, sticks in order to minimize contact with any potentially abrasive surfaces.

• For Small Holes: Repair small holes in a tent or rainfly with tenacious tape, a super strong tape designed to be lightweight, flexible and rugged for outdoor use.