Van Insulation Guide: Comparing Spray Foam, Thinsulate (Fleece), and Wool for Your Camper Van Build

Transforming a van into a camper requires careful planning, and insulation is a crucial component of that process. Whether you’re chasing summer sunshine or braving winter’s chill, the right insulation can make all the difference in comfort, energy efficiency, and even noise reduction. A well-insulated van helps maintain a stable interior temperature, reducing the need for excessive heating or cooling and ultimately saving energy.

Aguably, insulation is more important for summer than winter. Why? It is quite easy to heat your van up (think diesel or propane heaters), but it is much harder to cool it down if it has got very hot in the sun. AC units use too much power for all but the largest off-grid electrical systems.

With so many insulation materials available, choosing the best one for your van build can be overwhelming. Each insulation type has its unique benefits and drawbacks, depending on factors such as budget, climate, ease of installation, and environmental impact. Some materials excel in trapping heat during the winter, while others are more effective at reflecting summer heat away. Additionally, factors like moisture resistance and breathability play a role in preventing mould growth and maintaining air quality inside your camper van.

In this guide, we’ll compare three of the most popular insulation choices for camper vans: Spray Foam, Reflectix, Fleece (Thinsulate, or Recycled Plastic) and Wool. Each of these options offers distinct advantages, and understanding their strengths and limitations will help you make an informed decision based on your needs.

By the end of this guide, you’ll have a clear understanding of how each insulation type performs in different climates, its cost-effectiveness, and the level of effort required for installation. Let’s dive in and explore the best insulation choices for your camper van build!

Why Insulation Matters in a Camper Van

Insulation plays a crucial role in temperature regulation, keeping your van cool in summer and warm in winter. It also prevents condensation, reducing the risk of mould and rust buildup. When selecting insulation, key factors include R-value (thermal resistance), moisture resistance, and ease of installation.

1. Spray Foam Insulation

Spray foam insulation is a high-performance insulation solution that expands and hardens into place, creating an airtight seal. Unlike traditional insulation materials, spray foam conforms to every crevice, reducing air leaks and maximizing efficiency.

Pros of Spray Foam Insulation

High R-value: With an R-value of R-6 to R-7 per inch, spray foam offers some of the best insulation for camper vans in terms of thermal resistance.
Seamless Air Seal: Expands to fill every crack and gap, minimizing heat loss and preventing drafts.
Moisture Resistant: Acts as a vapor barrier, reducing condensation and preventing mould.

Cons of Spray Foam Insulation

Difficult to Install: Requires special equipment and expertise, making DIY application challenging.
Permanent: Once applied, removing spray foam is nearly impossible without extensive work.
Expensive: Higher upfront cost compared to other insulation materials.

Cost Estimate

• DIY Kit: $300–$500 for a full van.
• Professional Installation: $1,000–$2,000, depending on van size and labour costs.

Best For:

• Those looking for a highly efficient, long-term insulation solution.
• Van lifers in extreme climates who need top-tier insulation.
• DIYers comfortable with complex installation or those willing to hire a professional.

Spray foam insulation is an excellent choice for serious van builders who want maximum energy efficiency and durability. However, if you’re on a tight budget or prefer an easier DIY option, other insulation methods may be better suited for your needs.

2. Wool Insulation (Sheep’s Wool)

For those seeking the best insulation for camper vans that is eco-friendly and highly effective, sheep’s wool insulation is a top contender. Unlike synthetic materials, wool is a natural fiber that offers excellent thermal performance while also regulating moisture inside your van. This makes it a great choice for van lifers who want a sustainable, non-toxic, and breathable insulation solution.

Wool insulation is unique because it can absorb and release moisture without losing its insulating properties. This helps prevent condensation buildup inside your van, reducing the risk of mold and mildew—common concerns in mobile living spaces. Additionally, wool is naturally fire-resistant and sound-absorbing, making it an all-around excellent material for van insulation.

Pros of Wool Insulation

✔ Good R-Value: With an R-value of R-3.5 to R-4 per inch, wool provides effective temperature regulation in both hot and cold climates.
✔ Eco-Friendly & Non-Toxic: 100% biodegradable and free of harmful chemicals, making it a safe choice for people sensitive to synthetic materials.

Cons of Wool Insulation

✖ Moisture Absorbing: Wool can absorb up to 35% of its weight in moisture before it feels damp which is good if it can release the moisture, but if you have a problem with your vapour barrier it can just sit there absorbing moisture.
✖ Expensive: Wool insulation costs more than many synthetic alternatives, with a full van insulation kit ranging from $250–$500.
✖ Can Attract Pests: If not properly treated with natural pest deterrents like boric acid, insects and rodents may be drawn to it.

Cost Estimate

• $250–$500 for a full van

Best For:

• Eco-conscious vanlifers who want a sustainable insulation solution.
• Those travelling in both hot and humid or cold and dry climates, as wool regulates temperature and moisture effectively.
• Anyone sensitive to chemicals found in synthetic insulation materials.

Comparing Insulation Effectiveness in Different Climates

Final Recommendation: Which Insulation Should You Choose?

Choosing the best insulation for camper vans depends on your budget, climate, and overall van life goals. Each insulation material has its strengths and weaknesses, so it’s important to select one that aligns with your needs. Below is a breakdown of which insulation works best for different types of van builds.

Best as Insulation: Spray Foam

If budget and installation challenges aren’t a concern, spray foam is the most effective option for sealing every nook and cranny of your van. With its high R-value (R-6 to R-7 per inch) and moisture resistance, it provides superior temperature regulation in both hot and cold climates. However, it requires professional installation or an advanced DIY approach, and once applied, it is permanent. If you want maximum efficiency and long-term performance, spray foam is a solid investment.

Best for DIY Builders & Price: Fleece (Recycled Plastic)

This is my go-to. Why? It does not biodegrade or hold moisture. It is easy to install, reasonably in expensive (in comparison) and available just about everywhere.