» » Insulating a Campervan: The Must Read Guide

Insulating a Campervan: The Must Read Guide

Insulation is step #1 of campervan conversion

Once you’ve purchased the best van for your conversion project insulating a campervan is the first big job.

Campervan insulation can be a bit tedious because it involves some expense and hard labor and it’s not cosmetic; most of your hard insulating work will be covered up in future steps.

So while you’re planning, spending, trimming, stuffing, spraying, gluing and otherwise installing various insulation materials in your van, it can help to keep your eyes on the prize: A comfortable traveling and living environment that will last for many years of exciting adventure.

Table of Contents for Insulating a Campervan

Buying or Building a Van? What are we insulating against? Let's talk R-ValueVan insulation and your health
Materials for insulating
a campervan
Van build video series
Blocking Light
Air circulationHow to reduce moisture
and condensation
Please Comment
insulating a campervan Vansage Lake Wenatchee WA
Lake Wenatchee, WA. Image courtesy of Anubhav Saxena

Are you buying or building a van?

This guide will give you a knowledge foundation for thorough, carefully planned campervan insulation. By approaching the subject with diligence, you’ll be able to ensure a safe, comfortable campervan build.

Custom built van

If you’re having your van custom built, this guide will help you communicate with the builder about insulating a campervan for your particular travel needs.

Pre built van

If you’re searching for a pre-built van, used or new, you’ll know exactly what to look for. You’ll be able to assess the insulation system with an eye for detail and material quality.

DIY van builders

And our do it yourself readers will be prepared to plan and apply the most effective materials, tools and approaches to insulating a campervan.

What are we insulating against?

The obvious answer is cold, and perhaps you thought of heat. But it’s not nearly that simple. Consider insulation systems in houses. Builders and engineers have a long list of factors to consider. They draw from decades of hard earned experience, often based on issues specific to region.

But since you’ll be traveling to many different areas (I hope), the work of insulating a campervan goes beyond region.

For example I live in Washington state where I can spend a week in the dry desert, then some days in snowy mountains, head to the coast for a few days at the beach.

In this short time my van could be exposed to direct sunlight, wind, dust, snowfall, driving rain, ocean mist (full of corrosive salt) and more sun.

A partial list of what we’re insulating against

  • Heat
  • Cold
  • Noise
  • UV rays, light
  • Condensation
  • Mold and mildew
  • Leaks from rain, snow and ice
  • Rust and corrosion
  • Insects and other pests
  • Instability of insulation material
  • Dust, material off-gassing and other air quality concerns

Did I leave anything out? Probably, because insulation materials and methods are always being re-engineered with new inventions and installation systems.

My point here isn’t to dissuade or frighten you about the job of insulating a campervan. It’s only that I believe this is a very important step in campervan conversion that needs to be taken seriously.

van mountain scene vansage insulating a campervan
Image courtesy of Living4wheel

Let’s Talk R Value

From the Wikipedia article on R-Value

R-value is a measure of how well an object, per unit of its exposed area, resists conductive flow of heat: the greater the R-value, the greater the resistance, and so the better the thermal insulating properties of the object.

Since we’re limited on space in our vans, we’re naturally looking for R-value bargains. But there are other factors that are as or more important than R-value in terms of campervan comfort and health.

Examples of those factors include air flow and circulation, heating system quality and overall air quality in terms of health.

Some van builders get obsessed with R-value at the expense of these other issues and I believe this is a mistake. Read on for more.

Van insulation and your health

In my research watching Youtube videos and reading websites about insulating a campervan, I’ve seen questionable and outright dangerous examples of material use.

Beyond interior comfort and basic protection from the elements, some less obvious issues need to be considered. In particular:

Interior air quality

A DIY van builder in one video I watched allowed fiberglass insulation to stick out of cracks and gaps in her paneling material. This is a recipe for respiratory disaster and other health issues.

Fiberglass is not recommended for insulating a campervan. Fiberglass is okay in a house where it gets sealed 100% behind drywall.

It’s rare for a campervan to be sealed at that level, so some fibers will sift into the living space due to the constant vibration caused by driving.

If you travel with pets, you’ll want to consider their health as well. Dogs and cats need clean air and stable temperatures more than we do because they can’t simply open the door and leave the vehicle should it become dangerous.

Material off gassing and residue can be a real issue with construction materials. For example some dimensional lumber is treated with chemicals that may never fully dissipate and therefore is not intended for interior living spaces.

Some foam insulation panels off gas dangerous chemicals and are not meant for interior spaces. Avoid foams (however cheap the price) that aren’t verified for spaces meant for human habitation.

Daniel Petty Vansage Campervan Life with Dogs

Mold & mildew

Molds are a very real threat to air quality and can impact respiratory and brain health. The primary cause of mold is moisture from condensation and leaks.

I won’t try to cover the vast world of mold control and abatement here. Instead I’ll revisit the topic later in this article as it becomes relevant.

Noise and your health

In our mechanized world it’s easy to overlook noise as a health issue. Some people can roll along with all sorts of vibration, clatter, loud music…

Just because you’re not conscious of it, doesn’t mean noise is not affecting your health, so I’m including materials and methods for reducing road noise, vibration and rattling as important aspects of campervan insulation.

Materials for insulating a campervan

There are dozens of material options for insulating a campervan. Deciding which are best for your build can be overwhelming. Our aim is to narrow that list down to the most effective, proven products so you can get on with your build.

We also want to make you aware of what’s commonly used so you can assess pre-built and custom builder products.

REQUEST: As mentioned above, the list of insulation materials is virtually endless and ever-changing. If you know of a better product, a better way to install or have any other input, please leave a comment at the end of this post. We’re always interested in improving campervan build info. Thank you.

Below I’ve listed our favorite materials in order of installation so you can use this as a check list whether you’re building a campervan, or inspecting a van for purchase.

Sound Deadening Mat

Sound deadening mat is butyl rubber with aluminum sheeting. The best products are self adhesive and are meant to be applied directly to any metal that’s in contact with both outside air AND interior space.

For example, it’s great on wheel wells as it minimizes tire and road noise. It also goes on flat sections of steel between interior support struts.

Our favorite brand at the time of this writing is Noico Sound Deadener for its ease of application, high customer ratings and great pricing compared to similar products.

Mass Loaded Vinyl

I was first introduced to this product by one of the Sprinter build Youtube channels that I follow. I wish I’d known about it before I installed the horse stall matting in my own van (though this product also works very well).

Mass Vinyl protects against noise, heat and cold. If you’re starting from bare steel in a larger van, I strongly recommend adding this layer of insulation.

It’s best used in large sheets over floor framing, over wheel wells and in strips under brackets or other mounting hardware to reduce cold transfer and vibration noise.

Soundsulate Mass Loaded Vinyl

Blanket Insulation

Blanket insulation in homes typically refers to fiberglass roll insulation. For reasons stated earlier in this article, fiberglass is to be avoided in vans and other RVs.

Thinsulate Vansage Insulating a campervan
George installing Thinsulate in his new Sprinter. Subscribe to the Humble Road channel for tons of great campervan design and build info.

Fortunately there are other blanket insulation materials that are great for campervan insulation.

Thinsulate

Thinsulate started out as liner material for cold weather clothing. Not sure who started using it for RV and Campervan insulation, but it was a brilliant move.

Thinsulate is made from tiny polypropylene fibers and the gaps between these fibers reduce heat flow and allow moisture to escape.

From the Wikipedia page for the product, “Thinsulate is considered “the warmest thin apparel insulation” available. In fact, when equal thicknesses are compared, it provides about 1½ times the warmth of down and about twice the warmth of other high-loft insulation materials.”

As for cons, Thinsulate is pricey. Even so, it’s preferred by top van builders for its superior qualities such as breathability which allows for the elimination of dreaded moisture.

The best argument I’ve heard for committing to the expense of Thinsulate is: “You’ve spent a bundle on a van and you want it to be comfortable and safe for years to come, so don’t blow it trying to save a few hundred dollars on something as important as insulation. 

I tend to agree with that statement, though I also understand the realities of keeping costs under control.

Click to see Thinsulate insulation options on Amazon where there are several product options for volume and dimensions

Van build video series

I watch zillions of videos about campervan builds. This is one of the absolute best. In this edition, George shows you how he uses Mass Loaded Vinyl, Sound Deadening Mat and Thinsulate.

I highly recommend watching, liking and subscribing to his channel. Few van builders are as meticulous, knowledgeable and entertaining.

Recycled Denim

There are several recycled cotton insulation products available and some van builders use it as blanket insulation.

The advantages of recycled denim blanket insulation include low price and no-itch.

Unfortunately cotton takes a long time to dry out once it gets wet and that creates the possibility for mold and mildew. More on this issue in the section on air flow, below.

Another issue is that long term exposure to air born cotton fibers is a health risk. While not as serious as fiberglass, it is a real concern. Like fiberglass, recycled denim is nearly impossible to completely encapsulate in a van.

Foam Board

Foam board is very popular for DIY van insulation. It’s relatively inexpensive for the R value and comes in a variety of thicknesses and material compositions.

Foam board includes some cons that give me reservations. For example, many interior van surfaces aren’t flat and foam being brittle, it tends to crack when pressure is applied to fit curved surfaces. Those cracks need a lot of filling with soft materials like spray foam, caulk or blanket insulation material.

Foam board works for insulating van floors as long as it’s between framing members with rigid flooring over top so it won’t get broken down under the weight of furniture, equipment and walking (I believe that Mass Loaded Vinyl is a much better option on floors).

But even with all my reservations, I believe that a combination of foam board, Thinsulate and spray foam can make for a very effective and reasonably priced package for insulating a campervan.

A favorite of van builders is Polyiso with foil facing. RMax Thermasheath is the most common brand in the US and is commonly available at hardware stores.

Spray foam

Spray foam can be used to fill every nook, cranny and open cavity of a van. Professional foaming services are available in many areas. Some DIY van builders use many cans of the expanding foam called Great Stuff to insulate their entire van.

Spray foam also can be used to insulate small gaps or to fill cracks in rigid foam panels. If using expanding spray foam of any kind it’s important to keep some things in mind:

  • Mask off ALL mechanical areas such as door looks and other mechanism as the foam will gum things up.
  • Spray foam is messy and sticky and takes some practice to apply.
  • Once it’s sprayed in place and done expanding, it will need to be trimmed back so that paneling can be installed over it.
  • While working with spray foam, protect your skin, eyes, hair and lungs.
  • Once the foam is pumped (blown…) against the steel wall of your van, it may be very difficult to chase and locate the source of leaks in the exterior of the van, or from interior plumbing.


Sealants

Sealants are vital In our quest to insulate against leaks, pests, corrosion, mold and mildew, air leaks…  Sealants are necessary for preventing (or stopping) exterior leaks, sealing newly installed hardware such as fans, plumbing hardware, access panels, flanges, air conditioners and other hardware.

Like the rest of this topic, the best sealants to use for insulating a campervan can be a hot button issue. The good news is that there are many great products on the market.

We recommend against silicone and latex caulk commonly used in homes as they won’t hold up to constant vibration.

Here are some sealants commonly used for Campervans and RVs. These products come recommended by a wide range of RV and Campervan builders from many resources.

IMPORTANT: Your project is unique, so be sure to understand the details of your materials, environment and other factors that will impact your choice of sealants.

Do your research before committing to the use of any sealant. Contact manufacturers with questions, consult experts in the field, test products before application, search forums and social media resources…

3M 550 FC

  • Fast set and cure time for fast-paced processes and productivity
  • Elastic formula creates high-strength bonds
  • Multi substrate bonder works on a wide variety of similar and dissimilar substrates
  • One component adhesive for easy application with no mixing or guesswork


MasterSeal NP1

  • One-component, high-performance, non-priming, gun and tool grade, elastomeric
    polyurethane sealant.
  • Requires no mixing
  • Typically requires no priming to bond to many
    materials.


Dicor self leveling lap sealant

  • Creates a secure, secondary seal along roof’s edges, air vents, vent pipes and screw heads.
  • Adheres firmly to aluminum, mortar, wood, vinyl, galvanized metal, fiberglass and concrete.
  • Ideally suited for RVs and Campervans
  • One of the highest volume products sold in RV stores


Sikaflex

  • Seals cover plates, gaskets and coverings, floor moldings and door sills, light weight construction materials.
    wood or metal and door frames.
  • As an elastic joint sealer for air ducts and high vacuum systems, containers, tanks, and silos, gaskets in openings in walls or floors for ducts, etc, water retaining structures, aluminum fabrication. bolted lap joints.
  • Excellent adhesion on all cement-based materials, brick, ceramics, glass, metals, wood, epoxy, polyester and acrylic resin.
  • Fast cure rate, good weathering and water resistance, high durability, non-corrosive.
  • Can be painted over with water, oil, and rubber-based paints. (Preliminary tests recommended).



Blocking the Light Fantastic

Sunlight and UV reduction are not commonly included in articles about insulation, but light exposure directly impacts health and quality of life in your campervan.

Some vanlifers want all the glass they can get so they can take in the views they’ve driven so far to see. Others want less glass to maximize privacy and sleep quality, and minimize the impact of UV rays.

Personally, I prefer a middle ground with some windows and high quality coverings so I can choose the best of all worlds.

You can sew (or have sewn) heavy window blocking pads to both eliminate light and insulate against the cold transferring qualities of glass.

Here are some popular products for controlling light in your campervan

Reflectix

Reflective materials help control overheating of your interior from direct sunlight. Reflectix is a brilliant material that’s basically bubble wrap with foil on both sides.

It comes in rolls and can be easily cut with scissors. It’s both very light and just rigid enough to stay flat, so it can be easily held in place with a few pieces of hook and loop (aka Velcro).

Some Van builders use it against steel to insulate, though the R factor is not great for that application. Also, being plastic, it doesn’t breathe or allow for air flow.

I use it as window reflective sheets to reduce interior heat. My Reflectix sheets are easy to install and take down, and they store nicely between my bed and an outside wall.

Blackout Curtains

I’m a very light sleeper, so I have to take advantage of all the tricks I can for sleep improvement. One such trick is to create the darkest sleeping environment I possibly can.

Blackout curtains eliminate light from street lights, campsite fires and lanterns, even full sunlight for daytime naps. Some blackout material for curtains even has reflective material on one side, thermal protection qualities and other cool features.

Because every van is different, you’ll likely need to have your blackout curtains custom sewn (or sew them yourself). This is a very worthy expense if total darkness and privacy are valuable to you.

But “Blackout” doesn’t have to mean black. Turns out its the weight of the fabric and other qualities that eliminate light, not the color. So feel free to have fun with colors when shopping for blackout curtain material for your campervan.

Money saving tip: Find a pre-made blackout curtain design and color you like and have them hemmed, or do so yourself. 


Air circulation

The number one, most important consideration when insulating a campervan

Like nearly every other aspect of this topic, air flow can be a hot button issue on van and RV forums. We suggest that you do your own research and apply what you learn to your unique van build.

insulating a campervan vansage Campervan mold

A universally accepted concept

Building codes in nearly every region include strict requirements for air flow in crawl spaces, attics, between layers of interior and exterior sheeting, breathability of house wrap and other insulation products, air circulation in living spaces and much more.

If air flow is poor or non-existent, there can be no moisture reduction, mold will accumulate and air quality will be unhealthy.

Moisture, mold and rot, oh my!

For example, consider the under house crawl space, a common feature in homes in my state of Washington (Pacific NW, not DC, for our international readers).

Building codes in WA require that homes have adequate crawl space ventilation, no wood scrap or other debris and a barrier in the form of thick, black plastic sheeting.

If you’re buying a home in WA and the inspector reports that these requirements are not met, the bank won’t loan on the property until they are.

In short, a damp crawl space can result in rotting framing members and unhealthy mold spores that can lead to health problems for inhabitants, The solution is air flow

Air flow and your van insulation

Air flow eliminates a lot of the evils caused by moisture and we can take a lesson from these building codes to plan better campervan insulation.

Regarding vapor barriers in vans, instead of trying to block vapors from coming from the outside or infiltrating from inside cooking or other moisture producing activities, it’s better to have breathablility of all areas so that any moister that does occur can escape.

Every build is different and we can’t instruct you on your specific van. Please carefully consider air flow when designing your van interior.

How to reduce moisture and condensation in your van

My opinion is that we should avoid sealing everything behind plastic and instead, allow for breathability. This is because some moisture is inevitable, so our best defense is to let moving air do its job to carry away moisture that does occur.

Here are some of the best defenses against the ravages of moisture.

Mandatory fan use

Whether cooking or showering, the fan must be on. Of course this includes having a high quality fan installed in your van. Yes, good fans can be costly, but the cost of a good fan is nothing compared to tearing out rotten paneling and starting over on your build.

If you like to air dry clothing, it’s best to do it outside. If the weather won’t allow for that, make sure you’ve got the fan on and a window open.

Windows and floor vents

No matter how cold it is outside, you need a supply of fresh air inside. You’ll sleep better, feel better and avoid condensation all at the same time. Don’t allow the air in your van to become stagnant.

Heaters, air conditioning units and heat pumps function better with fresh air flow. Even when fighting extreme outside temps, it’s best to have a window cracked and/or a floor vent open.

Don’t skimp on heat

When airborne vapor cools down to a liquid and develops on cold surfaces, you get condensation. Keeping the temp inside higher than the outside (even by only a few degrees), you can avoid moisture build up on glass, steel and other hard surfaces.

Therefore, a great heating system is about more than just staying warm at night, it’s necessary for keeping your entire van interior healthy and safe.

Track and reduce humidity

Knowing the relative humidity inside your campervan can make all this very simple. Making sure that it’s between about thirty and fifty percent will pretty much eliminate any condensation issues.

With inexpensive and accurate humidity meters available, this doesn’t have to be guess work.

The ThermoPro TP55 Digital Hygrometer is a great little device with many positive reviews. It will help you keep an general eye on the moisture level in your campervan.

The Protmex MS6508 Digital Temperature Humidity Meter take humidity data to the next level with many powerful features including data storage for tracking the humidity in your van.


A dehumidifier can keep those percentages right where you need them. Unfortunately most vans don’t have a lot of spare room for bulky equipment.

If you tend to have high humidity levels, consider using a portable dehumidifier while parked between trips. This can help to eliminate any moisture that’s built up during a trip.

Of course your campervan will accumulate humidity while parked, so running a dehumidifier on a timer is a good idea. Just be sure to check the tank on a regular basis…


Thanks for reading. Please comment

We’d love to hear your thoughts on insulating a campervan. Do you have product recommendations, insulation experience or related stories, questions?

Please comment below.

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