The Ultimate Guide to Campervan Insulation: Foil, Armaflex, Wool & Cork Compared
Why New Van Builders Love Foil Insulation
It’s easy to see the appeal. Reflectix looks like the ultimate solution for campervan insulation:
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It’s shiny like a space blanket.
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It’s affordable and flexible.
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It promises to keep heat out in summer and warmth in during winter.
But van insulation isn’t just about comfort—it’s about managing heat transfer and moisture. And when it comes to condensation, aluminum foil can backfire if installed wrong.
Need professional help with your van build? Our Camper Van Build Service takes the guesswork out of insulation and ensures your van stays dry and comfortable for years. Contact us today to get started.
How Reflective Insulation Works in Vans
To understand if Reflectix or foil insulation belongs in your van build, you need to know what it actually does.
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Not true insulation: Aluminum has almost no R-value. By itself, it won’t stop heat from moving through your van’s metal walls.
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It’s a radiant barrier: Its job is to reflect infrared heat (like sunlight or heater warmth).
Here’s the key:
It only works with an air gap. If you glue Reflectix directly to metal or hide it behind panels, it turns into a conductor and loses effectiveness.
That’s why you’ll often hear seasoned vanlifers warn against slapping it directly on your van walls—it’s science, not opinion.
Pros of Using Aluminum Foil Insulation in Vans
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Excellent radiant heat control (when installed with air space).
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Cheap and accessible for budget van conversions.
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Lightweight and flexible for odd shapes and ribs.
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Strong vapor barrier—blocks moisture transfer completely.
For specific use cases, foil can be a great tool. But here’s where things get tricky.
The Hidden Dangers of Foil Insulation
1. Condensation Nightmare
A van is basically a moving greenhouse—you breathe, cook, and maybe shower inside, releasing liters of water vapor daily. Without ventilation, that moisture eventually condenses on cold metal.
If you’ve sealed your walls with foil, you’ve just trapped water inside. The result? Rust, mold, and hidden damage.
2. Mold & Rust Risks
Dark, moist, sealed cavities behind foil are prime breeding grounds for mold spores and corrosion. Many vanlifers discover the problem too late, once the panels come off.
3. Looks Can Deceive
Foil “looks” like insulation, but its R-value is near zero without air gaps. A thick layer of rigid foam or Thinsulate will always outperform it.
4. Van Rain & Puddles
Small gaps in foil act like escape hatches for vapor. The moisture finds cold surfaces, condenses, and you end up with puddles—or worse, dripping “van rain.”
The Smart Way to Use Foil in a Van Conversion
So should you ditch foil completely? Nope—it’s actually amazing when used correctly.
✅ Best Use: Window Covers
Reflectix shines (literally) in window inserts. They reflect sunlight in summer, retain heat in winter, and add privacy. Nearly every vanlifer swears by Reflectix window panels.
✅ As a Radiant Barrier, Not Insulation
Think of foil as a supplement, not the foundation:
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Install real insulation (rigid foam board, wool, or Thinsulate) for R-value.
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Add foil with an air gap where radiant heat is a problem (roof, floor).
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Seal carefully to reduce vapor leaks.
✅ Ventilation Is More Important Than Insulation
No insulation material can solve condensation without proper airflow. A roof vent fan (or two) is non-negotiable. It pulls warm, moist air out before it condenses.
To Foil or Not to Foil?
Here’s the verdict:
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Don’t use foil as your only insulation. It’s risky and ineffective.
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Do use it strategically for windows and as a radiant barrier with air gaps.
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Pair it with proper insulation like foam or wool.
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Never skip ventilation. A dry van is a happy van.
Want to skip the trial and error? Our Camper Van Build Service specializes in moisture-proof, energy-efficient insulation systems. Book a free consultation here and let’s build your dream van.
Insulation Comparison: Foil vs Armaflex vs Wool/Thinsulate vs Cork
When you’re building a van, it’s tempting to look for the “perfect” insulation. The truth? Each option has strengths and weaknesses. Here’s a side-by-side comparison to help you decide:
| Material | Insulation Value (R-value) | Moisture Resistance | Ease of Installation | Sound Deadening | Best Use Cases | Downsides |
|---|---|---|---|---|---|---|
| Aluminum Foil / Reflectix | Very low (near 0 without air gap) | Vapor barrier (but traps condensation) | Easy to cut, lightweight | Low | Window covers, radiant barrier (with air gap) | Useless when glued to metal, traps moisture, not true insulation |
| Armaflex (Closed-Cell Foam) | High (great thermal efficiency) | Excellent – resists moisture | Easy peel-and-stick application | High | Van walls, ceilings, floors | More expensive than foil, must be properly applied |
| Wool / Thinsulate | Moderate to high (good R-value) | Wool absorbs/regulates moisture; Thinsulate resists it | Easy to stuff into cavities | Medium | Walls, ceilings, odd spaces | Wool can absorb odors; Thinsulate costs more |
| Cork Insulation | Moderate (similar to wool) | Naturally resists mold & mildew | Easy panels, flexible sheets | Medium | Floors, eco-friendly builds | Less effective in extreme climates, pricier than foil |
Why We Recommend Armaflex at VanCowork
Looking at the table, it’s clear: while foil and cork have their uses, Armaflex is the most reliable, all-around option for van insulation. It’s moisture-resistant, easy to install, and provides both thermal and sound insulation—something you’ll appreciate on long drives.
That’s why here at VanCowork, we almost exclusively use Armaflex in our professional van builds. And for DIYers, we’ve made it easy:
You can grab Armaflex insulation directly from our on-site shop or order it online from our website.
Shop Armaflex Now or visit us in person to stock up before your next van project.
Why We Use Armaflex at VanCowork
At VanCowork, after years of experimenting with insulation methods, we’ve learned one thing: Armaflex outperforms foil in real-world van builds.
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It provides excellent thermal insulation with real R-value.
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It’s closed-cell foam, meaning it resists moisture instead of trapping it.
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It’s flexible and easy to apply directly to curved van walls.
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It doubles as a sound deadener, making your van quieter on the road.
That’s why in our workshop today, we almost exclusively insulate vans with Armaflex.
Good news? You don’t need to hunt it down—we stock Armaflex insulation in our on-site VanCowork shop and online store. So whether you’re DIY’ing or booking a professional build, we’ve got you covered.
Shop Armaflex Insulation Here or swing by our location to grab your supplies in person.
FAQs About Foil Insulation in Van Builds
Is Reflectix good for van walls?
Only if installed with an air gap. Direct application = zero insulation.
What’s the best insulation for vans?
We recommend Armaflex for most van builds—it’s moisture resistant, efficient, and easy to install. Alternatives include Thinsulate or wool.
How do I stop condensation in my van?
Proper ventilation (roof fans, windows) is more important than insulation type.
Can foil insulation cause rust?
Yes, if it traps moisture against metal. This is why installation method is critical.
Ready to Build a Smarter Van?
Insulation is one of the trickiest (and most important) steps in any van conversion. Done wrong, it leads to mold and rust. Done right, it keeps your van comfortable year-round.
Let us help! Our Custom Camper Van Build Service takes care of everything—from insulation and ventilation to full interior design.
📩 Contact us today to start your vanlife journey with confidence.
🛒 Or, if you’re going the DIY route, grab Armaflex insulation directly from our VanCowork shop or website and insulate like a pro.
