Van Conversion Guide
Base Build
💡 Jake’s Tip: You don’t need to cover 100% of the metal. Covering more than 50% of each panel doesn’t provide much extra benefit—save your money for other parts of the build.
🌡️ Thermal Insulation
Good thermal insulation helps regulate the interior temperature of your van—keeping you warmer in winter and cooler in summer. While it won’t create a perfect indoor climate, it does make van life more comfortable and helps your ventilation system work more effectively.
There’s a lot of conflicting advice online about insulation materials—some of it helpful, some of it just noise. Here’s what you actually need to know.
Materials
There are three main materials that I see used in DIY van conversions which all get the job done as thermal barriers. You can select any of these options and sleep easy knowing you’ve done right by your van.
It's just a matter of personal prefference based on the information which I’ve layed out for you in the chart, to pick whichever material feels right to you.
For more information on materials watch my video on the topic Here
Insulation
| Material | Positives | Negatives | Cost | Best Used For |
|---|---|---|---|---|
| Flexible Closed-Cell Foam | Lightweight, moisture-resistant, easy to install | Most expensive option | High | Irregular shapes, walls, ceilings in small vans |
| XPS Foam (Extruded Polystyrene) | Cheap, excellent thermal insulation | Hard to bend or shape to van curves | Medium | Flat walls and floors in larger vans |
| Natural Sheep’s Wool | Sustainable, breathable, easy to work with | Can absorb moisture if poorly installed | Fair | Eco builds, walls and ceilings in any van |
🛠️ Installation Tips
Cut insulation materials accurately to fill all gaps and cavities
Avoid leaving any exposed metal—these become condensation points
Use adhesives suitable for your material
Seal joins with cloth or foil tape
Focus on tricky spots: wheel arches, ribs, door panels, and roof
Work methodically—quality install matters more than overfilling everything
🧠 Why sealing matters: Condensation forms when moist air contacts cold metal. Every gap in your insulation is a weak point where moisture can build up behind your walls.
❓ Insulation FAQs
🚫 Common Mistakes to Avoid
Skipping acoustic insulation: It’s cheap, easy, and worth it.
Letting insulation touch bare metal without sealing gaps
Overlooking doors and ribs: Easy to forget, but key for sound and temp control
Thinking more = better: Don't overstuff areas or use multiple layers that prevent proper adhesion
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Not always. In small vans with good ventilation and breathable insulation (like wool), a full vapor barrier may trap moisture behind the walls rather than help. Focus instead on sealing insulation properly and allowing airflow behind cladding where possible.
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Yes, especially in colder climates. XPS or closed-cell foam boards work well here—just make sure they’re compressed evenly under your subfloor.
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Use what fits your build. Around 10–25mm for walls/ceiling is common in small vans. You don’t need to max it out—tight, sealed coverage is more important.
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These materials have their place, but they’re often overhyped. Alone, they don’t insulate much. Paired with proper materials (like foam or wool), they can reflect radiant heat—but don’t rely on them as your primary insulation.
📦 Recommended Products
Closed-cell foam rolls (eg. Car Builders or similar)
XPS insulation boards
100% natural sheep’s wool insulation
Cloth tape
Butyl-based sound deadening mats
Insulation is one of those parts of a van build that might not feel exciting, but it makes a massive difference. It helps manage temperature, reduces noise, and plays a big role in controlling condensation—which, left unchecked, can quietly ruin your van from the inside out.
In this step, we’ll break down both acoustic and thermal insulation: the different materials you can use, how to install them properly, and some tips to help you avoid the most common pitfalls.
🔇 Acoustic Insulation (Sound Deadening)
Installing sound-dampening mats helps absorb vibrations and block out road noise. This makes your van feel quieter and more relaxing—a small investment that goes a long way toward better sleep and a more comfortable living space.
✅ Key Benefits
Reduces rattles and road noise
Makes your van feel more like a home
Improves sleep quality and comfort
🔧 How to Install
Use butyl-based mats and apply directly to internal sheet metal surfaces
Focus on large flat areas prone to vibration (walls, ceiling panels, sliding door)
Fully cover the wheel arches to block road noise
Press the mat down very firmly—any loose spots reduce its effectiveness