6 Best RV Interior Winterizing Sealants For Drafts Nomads Swear By

That moment you’re settled in for a cold night and feel an icy whisper of air on your neck is a rite of passage for every RVer. You can crank the furnace all you want, but a drafty rig is like trying to heat the great outdoors. Sealing those tiny gaps is one of the highest-impact, lowest-cost upgrades you can make for winter comfort.

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Why Sealing Interior RV Drafts Is Crucial

Chasing drafts isn’t just about staying warm. It’s about efficiency, moisture control, and protecting your rig’s systems. Every cold stream of air that gets in is heated air that’s getting out, forcing your furnace to work overtime and burning through your precious propane.

This constant battle creates massive temperature imbalances. The floor is freezing while the ceiling is hot, and your furnace cycles on and off, stressing the components. More importantly, those cold spots where drafts enter become condensation magnets. Moisture collects, and that’s how you end up with hidden mold and mildew issues inside your walls or cabinets. Sealing drafts is a fundamental part of managing your RV’s interior climate, not just a comfort tweak.

Geocel Proflex RV: The Flexible All-Rounder

If you could only carry one tube of sealant, this would be it. Geocel Proflex RV is a staple in the nomad community for one simple reason: it stays flexible. Your RV is a box on wheels that twists, vibrates, and expands and contracts with temperature. A hard, brittle sealant will crack and fail within a season.

Proflex is designed for this movement. It creates a super-durable, waterproof seal that adheres aggressively to fiberglass, metal, vinyl, and wood—basically everything your rig is made of. Use it to seal exterior trim, window frames, and compartment doors. It’s the workhorse sealant you use where you need a permanent, reliable bond that can handle the rigors of the road. It’s a bit messy to work with, but the longevity is worth the cleanup effort.

Lexel Clear Sealant for Invisible Window Seals

Sometimes you need a seal you can’t see. Lexel is the answer. It’s marketed as being "19 times clearer than silicone" and, from experience, it lives up to the hype. It dries to a truly transparent, non-yellowing finish that’s perfect for sealing the inside edge of window glass against the frame.

This is a common spot for sneaky drafts, especially on older rigs. A tiny bead of Lexel can stop that air intrusion without creating an ugly, cloudy caulk line that ruins your view. It’s also incredibly tough and sticks to almost anything, even wet surfaces. While Proflex is the go-to for structural seams, Lexel is the specialist for any application where appearance is just as important as performance.

Great Stuff Foam for Gaps Around RV Plumbing

Some gaps are too big and awkward for caulk. Think about the holes drilled through your floor for water lines, propane lines, or electrical wiring. These pass-throughs are often draft superhighways, funneling cold air directly from the underbelly into your living space. This is where expanding foam sealant shines.

A quick shot of Great Stuff Gaps & Cracks (the minimal-expanding version) will fill the entire void, creating an airtight and insulated plug. Be careful not to use the high-expansion window and door formula, as it can be powerful enough to bow thin RV paneling. The key is to apply it sparingly, as it will grow to two or three times the size of the initial bead. Once cured, you can easily trim any excess with a utility knife for a clean finish.

Frost King Weatherseal for Doors and Hatches

Not all drafts come from static gaps; many come from things that are designed to open and close. Your main entry door, storage bay hatches, and even roof vents rely on compression seals, or weatherstripping, to keep the elements out. Over time, these foam or rubber seals get crushed, brittle, and lose their effectiveness.

You can check your seals with the "dollar bill test." Close the door or hatch on a dollar bill. If you can pull it out with zero resistance, your seal is shot. Replacing it is simple. Frost King offers a wide variety of self-adhesive foam and rubber weatherseals in different profiles (D-shape, P-shape, etc.). The most important step is to thoroughly clean the old surface with denatured alcohol before applying the new strip to ensure a strong, lasting bond.

Gorilla Clear Tape: A Quick Draft-Stopping Fix

Sometimes you need a solution right now. Maybe a sudden windstorm has revealed a new draft around a slide-out, or you want to temporarily block a window’s weep holes that are howling. For these situations, Gorilla Clear Repair Tape is an indispensable tool. It’s not a permanent fix, but it’s an incredibly effective and durable temporary one.

This tape has a ridiculously strong adhesive, is completely waterproof, and remains flexible in the cold. You can slap a piece over a drafty seam and it will hold all winter if needed. It’s also great for temporarily sealing off vents you don’t plan on using, like an air conditioner intake. Just be aware that the adhesive is aggressive, so it might leave some residue behind on certain surfaces when you remove it in the spring.

DAP Seal ‘N Peel: A Removable Winter Solution

What if you want to seal a window or hatch for the winter but need it to be fully functional again in the summer? DAP Seal ‘N Peel is a unique product designed for exactly this purpose. You apply it just like regular caulk, and it dries to a clear, flexible, and weatherproof seal. It effectively "glues" the window shut, stopping all drafts.

The magic happens in the spring. Unlike permanent caulk, you can grab a corner of the Seal ‘N Peel bead and pull it off in one long, satisfying strip. It leaves no residue and causes no damage to the underlying surface. This makes it the perfect solution for sealing up emergency exit windows or any other opening you want to temporarily decommission for the cold season without making a permanent commitment.

How to Find and Prep Drafty Areas in Your Rig

You can’t seal a draft you can’t find. The best time to hunt for them is on a cold, windy day when the temperature difference is greatest. Start by slowly moving the back of your hand along all the seams in your rig: window and door frames, slide-out edges, roof vents, and any point where something passes through a wall or the floor. You’ll feel the temperature drop distinctly where cold air is getting in.

For a more precise method, wait until dark. Have a partner stand outside with a powerful flashlight and shine it along every seal while you are inside in total darkness. Any crack or gap will show up as a bright sliver of light. Another great tool is an incense stick; the smoke will be visibly disturbed and drawn inward by even the smallest draft.

Once you’ve identified the culprits, preparation is non-negotiable. No sealant will stick to a dirty surface. Wipe the area down thoroughly with denatured alcohol or isopropyl alcohol on a clean rag. This removes dirt, oils, and old sealant residue, ensuring the new product creates a strong, permanent bond. Taking five minutes to prep properly will save you from having to do the job all over again next year.

Tackling drafts is a systematic process of hunting, prepping, and sealing. By choosing the right product for each specific job—whether it’s a flexible caulk, a removable seal, or simple weatherstripping—you can transform your RV from a breezy box into a cozy, efficient winter haven. A little effort now pays huge dividends in warmth and peace of mind all season long.