This is a long post. Want to jump to a specific section? Here’s the index:
What's insulation for? Heat insulation Noise insulation Comparison of insulation types Thinsulate Spray Foam Rigid Foam Flexible Foam Denim Wool Fiberglass Aerogel Glass bead paint Radiant barriers (Reflectix, Low-E) Carpet Noise insulation Constrained Layer Dampener Closed Cell Foam Mass Loaded Vinyl Other considerations Mercedes' factory insulation package Rust Windows Climate Control
What’s insulation for?
Insulation is supposed to stop or slow down the flow of heat or noise.
An empty Sprinter is a big metal oven in the summer, trapping and amplifying the heat of the sun. During the winter it loses its heat quickly to the outside. The climate control in the dash can’t keep up with the massive area of the van.
It’s also loud. Sound enters through the floor and wall panels and bounces around inside the van. There’s some factory sound damping stuck to the wall panels, but the van can still sound like being inside a big oil drum.
Insulation makes sure the heat stays where it should – inside or outside the van – and dampens the sounds like road noise to make the van quieter. You often need different types of insulation for heat and sound.
Stopping heat movement with insulation
Heat moves through conduction, convection, and radiation.
Think of the situation where the sun is shining on the outside of your van.
- Conduction is where the heat moves through a substance. The van’s metal body is a very good heat conductor. Heat in one part of the body spreads to other places fast. The heat from the sun gets spread from the outside to the inside of the metal van walls by conduction. You stop conduction by making a thermal barrier. In other words, you use a substance that does not conduct heat well (some foams, for instance) to block the transfer of heat.
- Radiation is where the heat is given off by a surface. You can put your hand near the inside van walls on a hot day and feel the heat being given off – radiated – even without touching them. The sun heated up the metal and now that heat is being re-radiated inside the van. Again, anything that blocks the heat from being radiated will be a good insulator.
- Convection is where the heat is transported through the air. Once the sun’s heat gets radiated inside the van, it heats up the air in the van. Warm air is lighter, so it rises and pushes cold air down. That creates air currents to move the heat around inside the van. You stop convection by filling gaps so the air can’t be transported. If you stop air from moving close to the hot metal on the inside of the van, it won’t be able to warm up from the radiated heat and then move that heat inside through convection.
Insulation is measured by how good it is at preventing heat from getting through. The unit of measurement most people use is the R value. The R value measures how well a material stops heat from being conducted through it, but not how well it prevents convection or radiation.
How does noise move?
Sound waves hit the metal walls of your van. The walls flex. The flexing recreates the same sound on the other side. You also get some noise transferred from the road through the suspension and into the vehicle frame. That makes the wall panels flex (resonate) and create the same noise inside the van.
So to stop the sound, you need to stop the panels flexing as much as you can (“dampen” them), and then muffle any remaining sound energy they produce.
The dampening is done by sticking relatively heavy butyl rubber and foil pads on any flexy metal surfaces. The muffling is done by using a layer of closed cell foam and – if necessary – a layer of free-floating heavyweight material such as mass loaded vinyl.
https://www.sounddeadenershowdown.com/ explains this in a bit more detail. Just remember, you aren’t necessarily going for the same level of soundproofing as their products will offer. Also, some of your heat insulation products will help with noise insulation too, whereas others will not.
Comparison of insulation types
A synthetic material made of polyester and polypropylene strands that puff up and trap air between them. The automotive version is slightly different to the type of Thinsulate you find in coats and gloves, but it works on the same principle. The automotive Thinsulate is sold primarily as an acoustic insulation (noise reducer) but it also has a pretty good R-value.
Thinsulate comes on a 60″ wide roll. That makes it ideal for a van, because the width of the roll works out just right for the width of the ceiling panels. Because it’s so wide, it’s also possible to span the large panel sections in the back of the van without needing joins. Joins are bad in insulation because they are a place where air/heat/noise can flow through.
Mostly you’ll want to glue Thinsulate in place with contact adhesive (like 3M 90). The Thinsulate comes with a scrim (a black non-woven fabric layer) on one side. It doesn’t seem to matter which side you spray the glue on, and the black layer looks better and has less loose strands than the white side.
Contact adhesives need to dry before you join the two pieces. Once you do join the pieces, moving them is hard. That means you have to cut and place the Thinsulate carefully.
Thinsulate also works well in the ribs and other less accessible areas of the van body. You can pull a long strip through the metal ribs using a wire fish, then it expands to fill the gaps.
People will often use a foil-faced foam product (LowE or Reflectix) in combination with Thinsulate. The LowE gets taped on to the ribs inside the van before the interior finish panels are put in place. Because the Thinsulate doesn’t completely fill the voids in the walls, the LowE has the air gap that it needs to do its job properly.
Thinsulate R value: Just over R3 per inch (5.2 for the 1.65" SM 600 automotive Thinsulate) Cost: $1.80/sq. ft from Hein on the Sprinter forum or his eBay store. He's also selling it on Amazon. Ease of use: High. Hazards: Relatively inert substance. Some small fibers will come off as you cut the roll of Thinsulate to size with scissors. It needs to be glued in place, and that glue (3M 90 or similar) is unpleasant. Wear a respirator.
Spray foam typically starts life as two liquids. When they’re mixed in the spray nozzle, they make a sticky foam. The van walls and ceiling are coated in anything from 1/2″ to 2″ of foam.
There are many companies that will spray your van for you. Alternatively it’s possible to buy cans of “great stuff” foam but it takes a lot of aerosol cans to foam a van. Instead, you can get large-size canisters with external spray nozzles. Those canisters give anything from 200 to 600 sq.ft of coverage.
If you are thinking of doing this yourself, remember to get a closed cell foam rather than an open cell one (which can hold water). Some people suggest getting the slower-expanding foam because it’s less likely to make the wall panels “pop” or bow. Mask off EVERY surface that you don’t want foam on. It’s sticky and very hard to remove when it sets. If you end up spraying it so thick that it sticks out beyond the wall, you can cut it off with a saw.
- On the Sprinter forum, one individual recommended www.sprayfoam-inc.com located in Albany, OR. They quoted around $300 to have a 170″ 3500 done.
- Others on the forum have quoted anything up to $1000 for a professional job.
- Some companies now won’t spray Sprinters because of the wall warping issues.
Spray foam R value: R6 to R7 per inch thickness. Cost: Around $1.20/sq. ft DIY, $0.50 to $1.50/sq. ft commercial. Ease of use: Medium. Requires masking of entire van before application. Requires protective clothing and respirator. Requires some skill to install well. Ambient temperature must be in a suitable range. Hazards: Requires full body protection when applying (messy clean-up) and off-gasses as it dries. Wear protective gear – a respirator (get the right size) and a tyvek coverall.
Rigid foam (Polyisocyanurate and Styrofoam)
Polyisocyanurate (RMax brand) and Styrofoam (RTech brand) insulation comes in rigid sheets, from 1/2″ thick to 2″ thick. The material has a very good R value for its thickness and weight.
The type of styrofoam used in this insulation is not the same as packing material. Instead it’s extruded. It’s much better to work with because it doesn’t crumble into tiny beads.
The sheets can be bent to shape for the walls and ceiling, but they might need scoring in order to fit around tighter radius bends.
People tend to glue the polyiso boards in place with spray foam. The boards can squeak if not attached properly. The boards are hard to fit in some panel areas where the internal metal overlaps the hole. They are often used in conjunction with either spray foam or Thinsulate in the metal ribs and other inaccessible areas of the van. It might be worth using spray foam to create a seal around each board so that moisture cannot condense against the van wall behind the foam boards.
One potential benefit to polystyrene board mentioned on the Expedition Portal site is that PolyIso can lose R value at lower temperatures, whereas the polystyrene does not. The same poster also recommends Vulkem polyurethane adhesive for polystyrene sheets because it remains flexible.
Rigid Foam R value: Rmax PolyIso is R6.5 per inch. R-tech polystyrene is R3.8 per inch. Cost: Rmax is $1.00/sq. ft for the 2" thick (R13.3) material. R-tech is $0.68/sq.ft for the 2" thick (R7.7) material. Ease of use: Medium. Needs cutting to shape and fitting into awkward panel areas. Must be glued in place. Hazards: Very few installation hazards. The board can be cut with a knife or a special foam board circular saw blade. The foam boards tend to be glued in place with spray foam (Great Stuff or similar) which can be messy and isn't good to inhale. It's possible for condensation to form between the foam and the metal van wall if the boards aren't sealed around the edges with spray foam.
Flexible foams (EPDM, Melamine)
An alternative to rigid foam products is foam sheets made of various materials such as EPDM or Melamine. These are typically open cell foams that have been treated with hydrophobic agents, or closed cell foams with more flexibility than the PolyIso or Styrofoam versions. They can often be rolled up for shipping. That also means they’ll fit to van walls better.
Aerocel is a closed cell EPDM foam designed for HVAC duct insulation. Graphite Dave on the Sprinter forum has used the 1″ thickness foam in his recent build. It has a claimed R value of 4.1. It’s not clear exactly how this differs from other neoprene foams such as those offered by FoambyMail.com.
BASF Basotect and Polymer Technologies’ Polydamp hydrophobic melamine foam are both open-cell foam that’s treated to make it water resistant. It’s intended primarily as a noise damping product, but it also has pretty good thermal conductivity. It’s very flexible. Sound Deadener Showdown uses this type of product in their van insulation projects.
Flexible Foam R value: ~R4 for 1" of either EPDM or hydrophobic melamine. Cost: $4.57/sq.ft for 1.5" EPDM; $8.25/sq.ft for 1.5" thick hydrophobic melamine. Ease of use: High. Flexible, easy to cut, easy to glue in place. Hazards: Working with the products should produce minimal dust.Melamine foam is formaldehyde based, if that worries you. Attaching with contact adhesive means you should wear a respirator.
This insulation material is cut up, fluffed up jeans, treated with mould, fire and insect inhibitor chemicals. It’s supposedly green because it’s recycled, but that’s not necessarily true. I’d also be concerned about the chemicals.
It’s relatively easy to work with. It comes in batts that you can cut to size/shape, although it doesn’t cut particularly cleanly so you might find it hard to get gap-free installs. It bends and deforms so it’s easy to put in difficult panel spaces.
The one big problem with recycled denim is that it’s not hydrophobic. In other words, if it gets wet it’ll soak the water up and then it will need to dry out. That means if any water condenses or spills against the van walls, the insulation will encourage rust. Even if you put a vapor barrier inside the van, there are weep holes in the cavities where water can get in.
Personally, this stuff scares me. It feels like a rust accelerator. If you live in a completely dry climate and if you have filled all the holes behind the side trim panels in your van, you might just be OK. Everyone else should probably not use it for van insulation.
Denim R value: R3.3 per inch (R6.7 for 2" thick batts) Cost: $1.12/sq. ft at 2" thick Ease of use: Relatively high for van use, but you'll have to piece batts together for the wider panels. Hazards: Low-itch for install. Some questions about the added chemicals though.
Like denim, this product is a “natural” material. Wool clothes are warm even when they are wet, so you’d think this was a great insulator, but wool clothes do hold water. Wool insulation does too. That means it has the same concerns as denim. As a positive, it’s pretty hard to set wool on fire, especially with the Boron flame retardant they add.
This stuff is not cheap. It makes Thinsulate look inexpensive. It is also mostly available in 3.5″ and 5.25″ thicknesses for residential installation. You’re likely to have to cut the 3.5″ thickness down to use in a van because the walls aren’t that deep consistently. There’s no point “stuffing” it in because compressing insulation actually reduces its R value rather than improving it.
I have similar concerns about this product to the ones I mentioned about denim. The Good Shepherd site specifically mentions the absorbtive properties of wool as a positive point. That might be true in a residential timber frame house, but it’s not so wonderful in a steel van.
Wool R value: 3.7 per inch (R13 for 3.5" batts) Cost: $2.19/sq. ft Ease of use:Relatively high for van use, but you'll have to piece batts together for the wider panels. Hazards: Getting too full of yourself for using such an environmentally sound material. Seriously though, wear a respirator when installing it because of the small fibers.
This is what houses are most often insulated with. It’s also used by a couple of the professional van upfitters. Just remember, fiberglass is a skin, eye and lung irritant. Long term exposure can cause respiratory problems. How well will you be sealing it away behind your walls? Also, it holds water.
Although you can get it in multiple widths, most fiberglass batts are 15″ wide to fit in to residential construction. You’re going to have to join several widths together inside the van cavities. Gaps between the batts are an opportunity for heat gain/loss.
Fiberglass R value: R3.7 per inch (R13 for 3.5" thickness) Cost: Around $0.35/sq. ft at 3.5" thickness Ease of use: Relatively high for van use, but you'll have to piece batts together for the wider panels. Hazards: Respiratory problems. Eye, skin and lung irritant. Long-term exposure (every time you use the van) can cause lung disease.
A space-age material that is super-light, hydrophobic, and has a super-high R-value. It’s also super-expensive. If you can get over the damage to your wallet, most types you can buy produce dust when you handle them, so they may create some installation issues.
Now you can buy it in blanket form to use for insulation.The blankets are flexible, so if you only have a thin space in which to put insulation, it’s potentially a good option.
For the “green” buyer who is considering denim or wool, check out Aerogel instead. It holds Silver Cradle certification for its low environmental impact during manufacturing and its low ecological impact. The blanket form is made of silica nanopores in a Polyester and Polyethylene batting matrix.
- Thermal Wrap is an 8mm thick non-dusty product.
- Spaceloft is a 10mm thick dust-producing product.
- There’s an eBay seller of Spaceloft aerogel charging $25 per linear foot 57” wide (4.75 sq.ft)
Technical side note: I have some issues with the hype. Thermal Wrap has a thermal conductivity of 0.023W/mK. This is the same as the thermal conductivity of PolyIso insulation. Spaceloft has a thermal conductivity of 0.014W/mK – so much better insulation, but still a very high price. In other words, although the original aerogel product has a very high R value, the blanket-based products might not be super-wonderful.
Aerogel R value: Spaceloft is claimed ~R10 per inch. Thermal Wrap is probably closer to R6 per inch. Cost: Spaceloft is $5.25/sq. ft on eBay. Thermal Wrap is $9.00/sq.ft from buyaerogel.com when bought in 40' lengths. Ease of use: High. Cut with scissors or a knife. Glue in place with spray glue. Hazards: Dust inhalation during installation and afterwards during use.
Glass bead spray-on insulation
The jury seems to be out on the benefits of glass bead rubberized external spray-on insulation. Its best use seems to be on the roof of vehicles which are constantly exposed to hot sun, such as school buses. The cost-benefit probably isn’t there for northern latitudes.
- LizardSkin claims to reduce heat and noise.
- Super-Therm (horrible site – go to the site map, then find the product) is an alternative. They claim “comparative R19 equivalent insulation” which is very hard to verify. Here’s an interesting story about a SuperTherm salesman who used it to insulate his new house.
Reflectix, LowE, other foil-faced foam/bubble-wrap radiant barrier products
The R value of the foil faced products is terrible. Probably less than R=1. But that’s because they aren’t designed to be used like other insulation materials. If you just stick them to the metal panels of your van, they won’t do much good. However, if you leave an air gap, they use that air as part of their insulation.
R values measure conduction. Foil-faced products work more through reductions in convection and radiation. They function as a radiant barrier.
The manufacturers claim pretty amazing R values, but they are approximations based on a residential setting with no air movement and a large air gap. In a van, if you use a foil faced product in combination with other insulation types, it’s helpful, but not R8 helpful. Just make sure it has an air gap in order to do its thing.
- Reflectix is bubble wrap with aluminum foil faces. Some people complain that it squeaks after installation. It’s also not so good for under-floor use because the bubbles don’t support as much weight as the closed cell versions.
- Low E/EZ Cool is a closed cell foam with aluminum foil faces. The closed cell foam resists compression and works well under flooring.
- Prodex is another brand of the same type of stuff. They have bullshit claims of R16 for their product, which puts me off. You will NOT see that R value in a Sprinter install.
- Remember to also buy foil tape. Get good quality high temperature tape because it’s going to be used in hot places in the van. You will need a lot of it (probably 3 times the length of the foil roll you buy) for an install in a van. If you are gluing it on, you’re missing the point.
Radiant barrier R value: Around R0.67 for the base material, but its reflective properties increase that number. For instance, LowE claim R3.8 for a situation similar to a Sprinter install. Do not believe the highly inflated values for this type of product. It needs an air gap to work properly. Cost: Reflectix = $0.48/sq.ft. LowE = $0.46/sq.ft Ease of use: High. Hazards: Other than potentially cutting yourself on the edge of the foil, very few hazards either with the install or during use.
Yes, even humble carpet has an insulation value. The R value varies between R0.5 for 1/8” nylon continuous filament level loop, 24oz/sq. yd and R2.2 for 1/2” wool spun yarn plush finish 43oz/sq.yd. So, adding that purple shag pile carpet to the walls and ceiling of your van for a ’70s look does also have some insulating value.
Sound insulation materials
There are no end of opinions about how to reduce sound levels in a van. One resource that comes up time and time again in conversation is the SoundDeadenerShowdown.com site. They recommend a specific 3-part approach. It’s slightly different for vans than for cars.
CLD layer (Constrained Layer Damper)
This is the layer that stops panels from resonating. To do that, it has to absorb the noise energy and convert it to heat energy. That means adding a semi-rigid mass to the panels. Thick, sticky rubber with a foil coating does the trick quite well.
The better quality CLD materials are butyl rubber rather than bitumen/asphalt based. They come with a foil face and an adhesive backing. You need a 1″ roller to install them properly and make sure they’re properly adhered to the metal walls, roof and floor. We used Reckhorn ABX 80 Mil thick. You can also get Reckhorn in a 100 Mil thickness. The hexagonal pattern on the foil even matches the original Mercedes dampening pads.
The SoundDeadenerShowdown site suggests that you only benefit from 25% coverage with butyl material. Any more, and you’re adding weight for very little additional noise damping. There were some areas of the van though, like the rear wheel wells, where we did 100% coverage. Gravel thrown up from the road hardly makes a sound now, whereas it was very loud beforehand. The SoundDeadenerShowdown site also has a specific entry for camper vans, where they suggest using thinner butyl rubber sheets and covering 100% of the wall area.
Closed Cell Foam layer
Designed primarily to prevent squeaks and rattles, this layer also has a marginal heat insulation role. The closed cell foam isolates the MLV layer (below) from the walls and stops wall and door panels from rattling against the metal van walls.
In most places, our walls already had a layer of LowE foil-faced foam as part of the heat insulation process. That served as a great CCF layer for sound insulation too.
We also bought a 50′ roll of 1/8″ thick 2lb polyethylene closed cell foam from FoamByMail. It’s non-absorbent, durable, and cuts really easily with scissors or a knife. Mostly, we used it as padding under our automotive tweed fabric wall covering, but the offcuts were also very useful in some locations round the van to use as a sound damping/rattle prevention layer.
MLV layer (Mass Loaded Vinyl)
Mass Loaded Vinyl is used to block the remaining sound waves as they travel through the air. Since most of the sound is coming from the underside and sides of the van, this layer is normally only applied on the floor and lower walls.
The MLV layer has to be isolated from the vehicle walls/floor in order to work properly. It can either be hung as a sheet, or suspended on a closed cell foam layer. If you hang it as a sheet, it’s likely you can use the wall panel screws/bolts to hold it in place.
For our van, we used Elephant Bark 1/4″ rubber (also called Stall Mats) as an MLV-type layer on the floor. We isolated it from the stock wooden van floor using a layer of LowE foil-faced closed cell foam. The full stack of materials gives us a good combination of heat and sound damping.
On the walls, we used DB2-4walls. It’s a .75lb/sf. product, 1/8″ thick. We didn’t use it throughout the van, but we did put sheets of it behind the door panels before we re-applied them.
Other things to think about
What about ordering Mercedes’ insulation package?
Don’t bother. Really. It’s an expensive option and it isn’t useful for either sound or heat insulation. Here’s a post by AKCub on the forum with pictures of what you get for your money when you order the X12 Crew Heating & Insulation Package. It’s only on the lower half of the wall panels, it doesn’t cover the entire panels, and it’s 1/4″ thick foam. Not much R value there.
Insulation and rust
Vapor barriers are used to stop condensation from forming in the insulated area of houses. The barrier either stops moisture from crossing at all, or “breathes” by letting moisture out of the building but not letting it in.
In a van, you already have a pretty good vapor barrier. It’s the metal walls, floor and ceiling of the vehicle. Adding another barrier inside the van means the insulation has no way to dry out if it gets wet. The general concensus appears to be not to try and make a vapor barrier on the inside of the van. If you’re using a foil-faced product, that can do a pretty good barrier job when it’s taped up, so you might want to make sure there’s still the potential for air flow around it.
Newer Sprinters are sprayed with anti-rust wax on their lower panels inside the van. They also have drip holes in the bottom of the walls for moisture to escape. Both of those things are necessary because condensation can easily form inside the van. Also, the plastic body trim panels are held in place with clips that poke through holes in the sides of the van. Those can leak in the rain. Before you insulate, you might want to seal the holes around the trim panel clips. You might also want to make sure you do not accidentally block the drip holes in the bottom of the walls. If you are gluing insulation in place, or spraying foam, it’s not likely to stick to the anti-rust wax.
Metal filings from drilling and cutting holes will quickly rust. If they’re left in the van walls or the floor channels, they’ll attack the paint and then start rusting the panels. Make sure you vacuum up any swarf after drilling, filing, or cutting. Also, be sure to prime any holes you make so they can’t rust.