Best Camper Van Insulation Guide (+ How To Insulate A Van)

For example, an inch of Mineral Wool is $0.80. An inch of Fiberglass is $0.60. Based on this, Fiberglass seems like the cheaper choice – right? But it’s actually not.

Mineral Wool has a higher r-value (4), which means you need less of it to accomplish the same insulation effect as Fiberglass (r-value of 3). They’re actually equal in cost – they’re both $0.20 per r-value.

In order to equally compare the cost in relation to how well it insulates your van you have to look at the cost per r-value – not the cost per inch.

This seems like it’s getting complicated. Let’s keep it simple.

To keep things easy, I researched the average price for all the cargo van insulation materials in this article and created a price comparison chart.

Columns 2 and 3 show the variation in price and r-value. This is what you’ll find online and in shops. But it’s not enough information.

The last column is what you want to pay attention to. It shows you how much you pay per r-value (which is what keeps you warm in the winter). Cost per R-value is how you can equally compare the cost of different van insulation.

Best Van Insulation	Cost per 1”	R-Value per 1”	Cost per R-value
3M Thinsulate	$1.10	3.4	$0.33
Polyiso Foam Board	$0.70	5.8	$0.12
XPS Foam Board	$0.42	5	$0.08
Spray Foam	$1.20	6.5	$0.18
Mineral Wool	$0.80	4	$0.20
Sheep Wool	$1.50	3.8	$0.39
Fiberglass	$0.60	3	$0.20
Foil Insulation	$0.30	1	$0.30
Ceramic Paint	$0.20	—	—

A Combination Of Van Insulation Options

The cheapest way to insulate a van is to use XPS foam board. This gives you the best insulation from heat transfer for the lowest cost – about 8 cents per r-value.

I used XPS foam board in some of my van – like insulating the van floor. Unfortunately, it’s fairly rigid, which doesn’t make it ideal for every area – more on this below.

The ideal camper van insulation is usually a combination of 2 or 3 types of insulation.

You will need to combine flexible insulation options (like thinsulate, sheeps wool or spray foam) for tricky spaces, as well as foamboard (cheaper, better insulation) for smooth/straight surfaces.

Choosing Van Insulation Based On Climate

Each type of camper van insulation has benefits and disadvantages. There’s no “best van insulation”. It’s not a one-size fits all solution.

Depending on how you plan to use your van, where you’ll travel, and what your budget is some options will be better than others.

If you plan to be in hot or humid climates, I recommend you consider Thinsulate insulation (which does not absorb moisture), closed-cell spray foam (works really well in hot climates) or a reflective insulation, like Reflectix or Low-E (these are radiant heat barriers and they work especially well in hot climates).

If you plan to be in cold climates, I recommend you avoid radiant heat barriers (like Reflectix or Low-E) and Polyiso foam board. Both of these options perform poorly in cold temperatures. XPS foam board, Thinsulate insulation and all spray foam options are good choices for cold climates.

#1 – 3M Thinsulate Insulation

Thinsulate is a synthetic insulating material created by 3M. It’s the same stuff that lines mittens, snow pants and other outdoor gear.

You’ll likely have to purchase it online and have it shipped as it’s not standard in most stores.

There are a few types of Thinsulate insulation available, so be careful which model # you buy.

For insulating a van use SM600L. SM600L has one side covered with black fabric, and one “open” side where you see the white fibers. This is the best way to insulate a van.

Be careful not to purchase model AU4002-5 – this item has both sides sandwiched in black fabric and a lower r-value, so it’s not as good for insulating a van.

Typically, Thinsulate insulation costs about $1.70 per square foot of 1.65-inch thickness. It’s marketed as an r-value of 5.2… but that’s for 1.65” of material, which is misleading.

To truly compare insulation, you need to look at the r-value per inch. Thinsulate’s r-value is 3.4 per inch.

I love Thinsulate as a van insulation option. It’s a bit more expensive, which is my only complaint.

That’s offset by how easy it is to install – you can touch it without getting itchy, it doesn’t off-gas or have any toxins to worry about, and it fits so easily into any tight space.

It also holds up really well long-term. It’s a hydrophobic material, which means it won’t absorb water or moisture. This is perfect for a van that might have roof or window leaks over time, and for frequently changing climates and humidity levels.

The most important thing to be aware of when installing thinsulate insulation is to make sure it is fully expanded. When it’s compressed it does not work as well. You want to carefully glue it in place so it won’t slump down the inside of your walls over time.

#2 – Polyisocyanurate Foam Board Cargo Van Insulation

Polyisocyanurate foam board (also called Polyiso or ISO) is closed-cell insulation for vans.

Compared to open-cell insulation, closed-cell foam board is much more rigid, and does a better job at preventing heat from passing through it.

Of all the foam board options on this list, polyiso is the most expensive and best insulating, except in colder temperatures.

While most cargo van insulation will work more efficiently in cold temps, Polyiso actually starts to lose efficiency around 60°F.

This means if you plan to be in climates colder than 60°F, this van insulation will not provide an r-value of 5.8, it will be less.

#3 – Extruded Polystyrene (XPS) Foam Board Camper Van Insulation

XPS is another rigid foam board option. It’s less expensive than polyiso, isn’t as effective at insulating and can absorb some moisture over time.

However, unlike other cargo van insulation options, XPS is able to maintain it’s r-value under compression, which makes it a great option for insulating a van floor.

I used XPS foam board for my van floor insulation. It is glued to the metal floor of my van with a sheet of plywood on top of it. Even after 4 years I’m still really happy with it.

Because XPS foam board doesn’t compress with pressure, even with all the extra weight I built on top of it, it’s the perfect option for van floor insulation.

#4 – Spray Foam Insulation for Van Conversion

Spray foam is a liquid aerosolized form of two compounds that expand up to 60x when mixed.

Its most common use is for insulation, but it’s also used for fire and vapor proofing as well.

You can use spray foam to insulate your entire van, or only use it for tricky to reach places.

Spray foam is a fantastic camper van insulation option, but installation can be really hard due to how much the foam expands.

If you get installation wrong, you’ll have a massive mess to clean up – most van lifers choose to have spray foam professionally installed (which will increase your cost).

I recommend using small cans of spray foam (I love Great Stuff) to seal any thermal bridges or small crevices (like the ceiling ribs) in your van.

After I insulated my van, I went through and added spray foam to the areas that I wasn’t able to cover with Thinsulate insulation and XPS foam board.

#5 – Mineral Wool / Rockwool Camper Van Insulation

While it has wool in the name, this is not at all similar to sheep wool insulation.

Mineral wool looks similar to fiberglass. It’s made from rock materials and is known for having good insulating and sound deadening qualities. It’s also fire resistant.

Just like fiberglass, touching it with bare skin can lead to temporary itching. It’s important to wear gloves and a mask when installing this.

Installation is fairly easy because, similar to sheep wool, this type of camper van insulation is sold in batts and can be shoved into small spaces.

Mineral wool is extremely durable, which means the insulating properties can withstand road life – with lots of vibration, and temperature/humidity shifts.

The downside to mineral wool is that it can contain VOC’s and the production process is not environmentally friendly.

#6 – Sheep Wool / Havelock Wool Van Insulation

Sheep wool is a natural wool insulation. It’s been good enough for Sheep for thousands of years, so why not vans, too?

In addition to being a natural resource with good insulating qualities, sheep wool is also a renewable resource which makes Mother Earth happy.

There’s a few interesting qualities to sheep wool – it is known to absorb chemicals in the air and improve overall air quality. It’s also sound deadening, fire resistant, and does not produce any harmful VOC’s or off-gas.

However, it can be prohibitively expensive. You also want to ensure you’re buying sheep wool that has been chemically treated, otherwise you may be importing bugs.

It’s also very difficult to find this type of camper van insulation in local stores, so you’ll need to order online and have it shipped.

Lastly, many reviewers say sheep wool has a funky “barnyard” odor that can last for up to a year. Personally, that’s enough of a turnoff for me.

I think Thinsulate insulation is comparable to sheep wool in many ways, and since it doesn’t smell weird it’s a better cargo van insulation choice.

A Note About Sheep Wool:

It’s both hygroscopic (water attracting) and hydrophobic (water-repelling).

What does that mean? The outer surface of sheep wool has water repellent properties, which means it will not mold. However, the inner fibers of sheep wool can absorb water — as much as 33% of its own weight in moisture.

This means you should not install a vapor barrier if you’re insulating your van with sheep wool. The vapor barrier will prevent moisture (absorbed into the wool) from escaping. Over time this will cause mold, rot, and rust problems in your van.

If you are not adding a vapor barrier to your van (more on vapor barriers below, but in general I do not recommend them), the wools water absorption capabilities can actually be super helpful!

In high humidity your sheep wool insulation will absorb excess moisture from the air and store it – creating a cooling effect.

In dry air the wool will release moisture to help balance the humidity levels inside of your van. This is especially great in cold climates because an increase in humidity levels will make the air feel warmer.

These are the same principles that apply to wool clothing, which is what makes it a great choice for hiking socks (to keep your feet dry and temperature regulated year-round) as well as for winter hiking outfits.

#7 – Fiberglass Campervan Insulation

I’m including fiberglass on this list, solely because it’s what most people think of first when starting an insulation project.

However, I highly do not recommend fiberglass for camper van insulation.

Fiberglass is one of the most common forms of building insulation. It’s made of fine glass fibers (causes temporary itchiness if touched) and typically consists of 30% recycled material which lends it to be one of the more eco-friendly insulation options available.

Unfortunately, fiberglass is prone to moisture retention which can cause rot, rust, mold and mildew problems. That’s an immediate show stopper for any camper van insulation.

While it’s inexpensive and also provides good sound deadening qualities, the pros are far overshadowed by the cons.

It’s tricky to install, absorbs too much moisture, and the constant vibrations from driving can dislodge the fiberglass fibers into the air – causing irritation to your lungs, eyes and skin.

#8 – Campervan Foil Insulation (Reflectix, Low-E, EZ-cool)

Campervan foil insulation, also called reflective insulation, is made of two exterior reflective layers with an interior layer of bubbles, foam or another insulation suited for preventing conductive heat transfer.

In addition to slowing conductive heat transfer with the middle material, the reflective outside layers work by preventing radiant heat transfer, too. (more on the different ways heat can transfer below!)

Reflective insulation requires at least ¾ inch air space in order to be effective. This is different than how other cargo van insulation options on this list work – the air gap is required in order for heat transfer to be slowed or prevented.

This space is called dead airspace and it’s important that the air is still and not circulating in order for this insulation method to be effective.

If you do not have dead airspace, installing reflective insulation is a waste of time and money.

Reflective insulation works well in warm climates because it prevents radiant heat transfer. However, it’s not effective at conduction heat transfer so in cold climates you will need a second form of insulation for a van (you can choose any of the other van insulation types in this article for cold climates).

#9 – Ceramic Insulating Paint Cargo Van Insulation

Ceramic insulating paint is a relatively new technology that was initially introduced by NASA as a way to help cool rocket ships upon reentry.

The paint contains tiny microspheres of glass and ceramic that act as air pockets to prevent heat transfer through the paint.

Ceramic is a great material for blocking heat transfer – that’s why many mugs are made out of it. The ceramic material keeps the heat inside the mug (in your coffee). The same applies to ceramic insulating paint.

Ceramic paint (like Lizard Skin, or paint mixed with a ceramic additive) is marketed as “insulating”.

However, it’s important to point out that there have been no independent studies that have proven the effectiveness of insulating paints. And, there are a few studies which show it has no measurable impact. 

Ultimately, insulating paint isn’t going to decrease the effectiveness of your van insulation, but it’s quite expensive with no guaranteed benefit. Even if you go this route, I’d still recommend having another form of insulation in your van.

How To Insulate A Van

Insulating my van was one of the easiest DIY projects for my entire build. It’s also a quick project, which is nice.

In total, I spent about 2 days insulating my van – but it could definitely be done in under a day.

Because vans are such strange shapes, insulating can be a little tricky.

For that reason, I’m breaking down installation of camper van insulation into a few different categories: insulating a van floor, the walls, ceiling, and the van doors.

Step 1: Insulating a Van Floor

The best van floor insulation is XPS foam board. This is the only type of foam board insulation that maintains its shape and ability to insulate when it’s under pressure.

This means you can put plywood on top of XPS foam board, and build on top of it. The heavy weight won’t compromise your van floor insulation.

My Ford Transit floor has ribs on the floor, it’s not a smooth, flat surface. The ribs stick up about 1/4 inch. I cut strips of ½” thick XPS foam board to fit between them.

Because the floor isn’t perfectly flat, the strips of XPS fit perfectly between the ribs to create a better flat surface for the second layer of van floor insulation to sit on (pictured).

Is this step absolutely necessary? No. But it does give an extra amount of insulation, and because I do van life with my dog it was extremely important to me to maximize my camper van insulation and maintain safe temps inside my van to keep my dog safe.

Would I do it again? I think 1/2″ insulation on the floor is enough (unless you’re doing winter van life, then I’d install 1″).

I would definitely increase the amount of ceiling insulation I have. I’d add as much as I could while still having room to stand up inside my van.

In the summer, the sun heat that comes through my roof is my biggest problem. I’d rather have more ceiling insulation to keep cool in the summer than insulating the van floor more.

To install XPS foam board to your van floor use 3M Hi-Strength 90 Spray Adhesive.

To glue XPS foam board to another piece of XPS foam board use Loctite PL300 Foamboard Adhesive.

Pro Tip: I found that the 3M adhesive works best when I spray both surfaces (foam board and van floor) and wait a few seconds for the glue to tack up before pressing the foam board securely onto my van floor.

Note: if you plan to build a camper van with a shower I recommend you do not insulate the van floor below the shower pan.

The shower pan will add 2-3 inches to your floor height, and decrease your head clearance – especially if you’re tall. Insulating the floor under the shower pan decreases head space even more and may not be worth losing the extra inch.

Step 2: Insulate A Van Wall

Walls and doors are the most time consuming places to insulate a van. They’re full of curved metal and tiny crevices.

If you’re looking for a quick and easy job that’s “good enough” I recommend insulating with Thinsulate, or another flexible insulation material. It’s really easy to install.

However, if you’re looking for the most effective insulation possible (like me) I recommend a combination of foam board, Thinsulate insulation and spray foam.

Foam board is the cheapest and most insulating option. Start with this and install it everywhere possible (the flat sections of wall). Use 3M Hi-Strength 90 Spray Adhesive to adhere to the van wall.

Once you’ve added as much foam board as you can, fill in the remaining areas with Thinsulate insulation.

Thinsulate is easier to install, but it’s more expensive and doesn’t insulate as well as foam board – which is why it’s the second best option for more complicated installation spaces.

Thinsulate insulation works best when it’s fully expanded, so place it in each cavity without compressing it.

Pro Tip: My Ford Transit had several long, narrow channels that ran down the walls. It was hard to shove insulation into these because the openings were only 1-2 inches wide. Instead, I used a fish tape tool to snake it through (I have no clue why it’s called fish tape, it’s basically a tool to help run wire through walls).

If you are using sheep wool instead of 3M Thinsulate insulation you’ll want to use twine instead of spray adhesive. String the twine through the holes in the sheet metal and tuck the sheep wool behind it.

The final step is to insulate van walls is sealing any gaps (which will become thermal bridges that allow hot air in) with Spray foam.

Pro Tip: This stuff works much better if you’ve shaken the can really well first. If you don’t shake it well enough it comes out of the can really slowly.

Spray foam also works well in the tiny crevices too small to get Thinsulate insulation into.

It expands a LOT, and pretty quickly, so go easy at first. If you spray too much on, it’s easy to fix. Just wait for it to harden and then cut off the extra with a utility knife.

Step 3: Insulate a Van Ceiling

There are two primary locations you need to install insulation on your ceiling: the flat surfaces in between the ribs, and inside the support ribs.

I see so many people skip insulating the supporting ribs on their ceiling (because they truly are a huge pain to insulate), but this is a big mistake because they’ll let so much hot air in if you don’t insulate them!

Flat surfaces can be covered with foam board. I recommend using XPS foam board to insulate the van ceiling because it will flex slightly to the contour of the van. It’s also the most insulating and least expensive option.

Polyiso foam board is completely rigid and too difficult to use for van insulation. I do not recommend it for this purpose.

I used 1 inch XPS foam board on my van ceiling, but in retrospect I wish I had used at least 2 inches.

The roof of my van is where I take on the most heat during the summer. More ceiling insulation would mean less heat entering my van when the sun beats down on it.

After insulating the large, flat-ish spaces with foam board, I insulated the ceiling ribs with Thinsulate. The Fish Tape comes in handy for these areas, too.

Step 4: Insulate A Van Headliner

There’s a massive amount of heat that comes through the headliner area, above the cab. I’m not sure if the roof angle of it takes on more heat from the sun, or if it’s because of something else, but it’s noticeably warmer.

Originally, I didn’t insulate behind my headliner but it was so warm that added insulation after a few months.

In my experience, the best way to insulate a van headliner is without removing it. While it can be removed, it requires you to find approximately 6 million different pins (I’m exaggerating… kind of) and unfasten them without breaking them. They’re usually plastic and very breakable so you’ll probably break a few. It’s just not worth trying to take it off to get behind it.

Instead, I used Thinsulate to insulate the headliner. I gently pulled back the headliner fabric so I could stuff my insulation behind it.

The gap behind the headliner fabric was fairly deep, so I added two layers of Thinsulate insulation for increased r-value. It made a huge difference!

Step 5: How to Insulate A Van Door

The easiest way to insulate van doors is to remove the plastic panels that cover them, then add Thinsulate insulation to the open cavities.

They panels are usually held on with plastic pins that are barbed at the end. I gently pulled on them until they released.

Be careful not to twist or pull too quickly because you can break the plastic if you go too fast Don’t worry – if you do accidentally break the pins most local hardware stores, like ACE, sell replacement pieces.

Once you have access to the hollow cavity in the doors you can gently push Thinsulate insulation into the open space. Be sure you don’t compress it. Thinsulate works best when it’s fully expanded.

Doors can let in a lot of cold during the winter. I didn’t have my back doors insulated during my first winter on the road and it was noticeably colder in the back of my van.

After I insulated my back doors I noticed that it was warmer in the back of my van, and surprisingly a bit quieter too! (Thinsulate has sound absorbing properties)

One very important thing to remember when insulating your van doors is that they’ll have water in them at some point. This is completely normal. When it rains water can get in through the window or other seals. Doors have holes in the bottom to allow water to drain out, so be careful not to block those holes with your insulation. I do not recommend using spray foam in doors for this reason.

Step 6: Van Window Insulation

Do not overlook the importance of high quality window covers to keep your van cool.

Window covers are important for both privacy and preventing heat transfer.

Many window covers are made from foil insulation that works by preventing radiant heat transfer. These are popular because they’re fairly cheap and easy to DIY, hold up well, and do a decent job at keeping the heat out. However, they’re less effective in colder temperatures.

During my first year in the van I used these inexpensive Ford Transit reflective window covers from Amazon for my front windows and windshield. They’re fairly cheap and work well enough.

Eventually, I upgraded to window covers from VanMade Gear. These are more expensive, but they’re top quality. They completely block out the light (no gaps!) and are really insulating.

The Basics Of Camper Van Insulation

So far we’ve covered the best camper van insulation options, and how to insulate a van.

That might be enough information for you. But if you’re looking for more detail about how insulation works (this is helpful in deciding which type of van insulation option is best for your van, and the climates where you’ll be traveling) keep reading!

These are a few items related to van insulation that are important to have a general understanding of.

1. Insulation

Insulation slows the transfer of heat.

A strong insulating material will transfer heat slowly.
A poor insulating material will allow the transfer of heat more quickly.

2. Heat Transfer

Heat transfer can occur in 3 ways: radiation, conduction and convection. 

All 3 types of heat transfer will occur in your van. Having an understanding of each will help you determine which insulation material is best.

3. R-Value

Insulation is measured by its r-value. R-value is a standard unit of measure that allows equal comparison of different types of insulation.

R-value indicates a materials ability to prevent heat transfer through itself.

A high r-value insulation is more resistant to heat transfer (a better insulator) than materials with a lower r-value.

When comparing van insulation options, make sure you’re looking at the R-Value per inch and not the total R-Value. Total R-Value isn’t good to compare materials of different thickness.

4. Thermal Bridges

A thermal bridge is a weak spot in your insulation, like a gap or a seam, where heat can transfer through faster than the surrounding areas.

You want to avoid having gaps in your insulation where heat can penetrate (like the ribs on your ceiling). The more thermal bridges you have, the less effective your van insulation will be.

As annoying as some of these areas are to insulate, it’s crucial for temperature regulation in your van.

5. Vapor Barrier

Do you need a vapor barrier? Does a vapor barrier do more harm than good? This is the most polarizing topic for van builders.

First of all- what is it? A vapor barrier is intended to keep moist air (like what you exhale) from reaching a cold surface (like the sheet metal walls of your van) and creating condensation.

When moist air contacts cool surfaces it creates condensation. Condensation can lead to mold, mildew, rust and rot. It’s really bad for a van.

Supporters of a vapor barrier argue that preventing condensation from occurring on your van walls and ceiling will prevent rust. Thereby keeping your van in good working condition for longer.

The case against vapor barriers argues that while the concept is correct (and works for some applications – like a house), the reality for van dwellers is that it’s impossible to keep moisture from getting into your walls.

Water will get behind your vapor barrier eventually. Roof and window leaks aren’t that uncommon. Then, the water will be trapped by the vapor barrier.

My van came off the dealer lot with a teeny roof leak. The leak was so small it took me a few weeks to notice. Even brand new vans have problems!

While a vapor barrier is good in theory, the reality is it’s not practical for a van. I do not recommend using a vapor barrier when insulating your van.

A vapor barrier will trap water inside your walls, causing rust, mold, mildew, and rot. Additionally, most camper van insulation does not work as well when it is wet, so it will decrease the efficiency of your vans insulation.

Choosing The Best Camper Van Insulation

There are several considerations to weigh when deciding on the best camper van insulation for your build. It’s not one-size fits all. If you plan to travel exclusively in warm climates you may choose different insulation than if you plan to be in extremely cold climates.

1. R-Value – Pick insulation that has the highest r-value while still meeting your other requirements.
2. Cost – There’s a wide variety of prices. Typically, you’ll pay more for higher r-value materials.
3. Ease Of Installation – Selecting a flexible camper van insulation material will make installation easier.
4. Moisture & Mold Resistance – The best camper van insulation material is one that is hydrophobic (repels water).
5. Toxicity – If you choose a camper van insulation that off-gasses you’ll want to do your own research into the potential health concerns.

Best Insulation For Van Conversion

The “best” insulation for a van conversion depends on your use case.

Overall, I think Thinsulate is the best insulation for a van. The best budget insulation for a van is XPS foam board. For a natural insulation, the best option is sheep wool. And, if you’re goal is to have the highest r-value (the most effective insulation possible) then you’ll want to consider spray foam.

Best Overall – Thinsulate Insulation

The best way to insulate a cargo van is with Thinsulate. Thinsulate insulation does not absorb water, will not mold, is non-toxic, is very easy to install and conforms easily to van contours and curves.

Best Budget Option – XPS Foam Board Insulation

XPS foam board is the best van insulation on a budget. As one of the least expensive options, it’s also one of the most effective types of insulation for a van and has a high r-value.

XPS foam board is also best for insulating a van floor. Van floor insulation must be able to maintain its effectiveness under compression and XPS foam board is the only camper van insulation which meets this requirement.

Best Natural Option – Sheep Wool Insulation

Sheep wool camper van insulation is the best natural option. Sheep wool has a slightly higher r-value to Thinsulate but absorbs moisture and has an unpleasant smell that can take up to a year to dissipate.

Keep in mind that typically it is treated with chemicals to prevent pests, so it’s not always a truly natural product.

Best R-Value – Closed-Cell Spray Foam

The highest rated r-value camper van insulation is closed-cell spray foam. 

Spray foam camper van insulation has an r-value of 6.5. All of the other cargo van insulation options have an r-value under 5, except Polyiso foam board which has an r-value of 5.8.

Ultimately, I think the best way to insulate a van is to use a combination of insulation materials. Flexible materials are great for hard-to-install locations. Foam board provides good insulating properties for less cost, and is a good option for flat locations, like the floor.