Camper Van Spray Foam Insulation: Our Process
** Disclaimer: We are not professional spray foam installers. We are just a normal couple that enjoyed building our DIY van. The advice shared in this blog is just from our personal experience, and is by no means professional advice that should be trusted without doing your own research.
Spray foaming your van is a big decision and we were extremely nervous to cover our beloved van in spray foam. We put hundreds of hours’ worth of body work into the van and knew that getting the spray foam application wrong could have serious consequences to the metal panels of the van. Along with the possibility of messing up the exterior of the van, spray foam insulation is extremely difficult and time consuming to remove if you manage to get it in places that you don’t want it. With these downsides you’re probably wondering why would anyone take the chance and spray foam their van? In the first section of this blog we’re going to explain the key advantages that led us to choosing spray foam van insulation. We’ll then get into the exact methods we used to prep the van, apply the spray foam, and tailor the fit of the foam to a point where we could install the walls.
If you’re on the fence about spray foam installation for your van check out our blog where we compare different types of installation. (Note: this blog was originally written in 2021 and although we try to update it, prices/certain information may have changed).
Why We Chose Spray Foam Insulation
Before we settled on closed cell spray foam insulation for our cargo van turned camper van, we researched multiple different types of van insulation. In simple terms, the main point of insulation in a sprinter van is to keep cold air out when it's cold outside and keep hot air out when it is hot outside. Because a van is essentially a metal skin with a few supports added in, thermal insulation is a must if you want to have a comfortable camper van in any climate that you want to travel to. Closed cell spray foam insulation was our choice above foam board insulation with great stuff, wool insulation, open cell spray foam, and reflectix insulation. So let's dig into why we chose closed cell spray foam for our sprinter van insulation.
Key advantages of spray foam:
Higher R value than other insulation types
Spray foam is also a sealant and can reduce noise
Spray foam reduces thermal bridging
Condensation protection
Spray foam is easy to install
Let’s dig into the advantages listed above a bit more.
1) Higher R value than other insulation types
The R value, or the efficiency rating of insulation, is an industry standard that tells you how well a certain type of insulation will prevent heat transfer. The higher the R value, the better the insulation performs. One inch of spray foam insulates better than almost any other type of insulation on the market for vans. The other thing to consider with spray foam is that it will expand and work its way into cavities that are really difficult to stuff other types of insulation in. The metal frames of vans have many of these cavities and make it almost impossible to get more traditional wool or fiberglass insulation in. If you can't get the insulation into the cavities then the R value decreases as the thickness decreases. Overall closed cell spray foam insulation has a high r value and this played a big role in why we chose it.
2) Spray foam is also a sealant and can reduce noise
Spray foam insulation doubles as a sealant that blocks air movement. It can expand into almost any cavity that you spray it into and prevent air from moving. You do have to be careful with this aspect because if the foam doesn't have enough ways to get out of the cavity, it can deform the flat surfaces on the metal of the van. Our Sprinter van was an older van that we did a lot of body work to and had to put a few holes in the floor for electrical and plumbing connections. The spray foam was another layer of insurance for sealing all of these areas up and making sure we didn't have areas for air to circulate through the van where we didn't want it to. This means that there is a much smaller chance for an air gap after the foam expands and fills all of the open cavities. As well as sealing the van up spray foaming a van creates a vapor barrier if it is applied correctly. Additionally, due to it sealing properties spray foam also reduces exterior road noise creating a quieter ride in the van.
3) Spray foam reduces thermal bridging
Thermal bridging happens when a conductive material runs through an insulating material. The conductive material creates a bridge for heat to flow through. This effectively bypasses the insulation and can create condensation issues inside the van. Spray foam helps with this because it covers every inch of sheet metal on the van if you apply it correctly. Metal is good conductor and any areas of exposed metal on the inside of your van will conduct heat into or out of your van depending on the weather. Another area to be mindful of regarding thermal bridging is the fasteners that you use to attach your wall/cabinets to your van structure. If you use metal fasteners that go into the metal frame of your van and they are visible on the inside, they will create a bridge and can cause condensation
4) Condensation protection
Condensation can also come in a different form than we just discussed with thermal bridging. It can be hidden inside of the walls if you use porous insulations such as wool or fiberglass. The reason this is such an issue is that condensation is water, and water constantly being on the inside metal surface of your van can cause rust that you cannot see. Once you do finally see it on the outside of your van it's too late because it's eaten the walls of your van away. The reason spray foam doesn't have this issue is because it adheres to the walls of the van and doesn't have a gap for air to sit against the metal. In other words, it creates a solid barrier that protects against condensation and helps control moisture. However, there is one downside to this that we will get into during the installation portion of this guide that has to do with the humidity during application.
5) Spray foam insulation is easy to install
Ease of installation was a big bonus for us on choosing spray foam. Granted there is a lot of prep work and planning that goes into using it, but the application process only took two hours. Once you start spraying you don't stop and it goes quickly. As long as you tape things off properly and don't get crazy with the amount of foam you spray, the process can be easily accomplished in a weekend. We did have to saw out some extra foam off of some areas, but that process was relatively quick as well. For us personally, it was faster than stuffing insulation in and tying it up in the van so it didn't fall back out before we put the walls in.
How We Applied The Spray Foam To Our Van
The spray foam process:
Prepping to spray
Spraying the expanding foam insulation
Clean-up
Let’s dig into our process listed above a bit more.
1) Prepping to spray
Prepping to spray includes a lot of critical steps in order to make the job of spraying the foam successful. The first step is to make sure you have conduits run for any wiring or plumbing that you want to be inside of the walls. The only conduits we ran were for our ceiling lights because we didn’t put any plumbing or electrical in our walls. The main reason we chose to not put things in the walls was that we wanted to be able to see and access any issues that we might have with those systems. Along with the conduit for the ceiling lights, we also framed out the roof, walls and floor. We didn’t want to attach these things straight to the metal of the van so we framed it out similar to a house with studs (shown in image below).
With all the structure and conduits run, the next step of the prepping process is masking off any areas you don't want foam. This may seem trivial but it is critical because spray foam will stick to and ruin almost anything. We made sure to cover our windows and the cab area with thick plastic sheeting and duct tape. We also covered the areas that our fan and AC unit were going to be mounted in. One area that we really didn't think about was the back of the van where the doors were open. Spraying the foam creates a lot of splatter, and when we were foaming the van floor in the back some got onto the exterior of the van because the rear doors were open. If we were to do it again we would wrap the plastic around the van a few feet past the door opening. Another thing to note is that even if places are masked off well, if you spray the foam on thick enough you'll still have to cut/break it in order to get to the tape or plastic beneath. So try to avoid spraying the areas you have masked off.
The last part of the preparation process depends on the type of spray foam you're using. We used the DOW FrothPak 650 so we’ll refer to what we did for that specific system. The DOW FrothPak is a polyurethane foam that consists of two chemicals to create closed cell insulation once mixed. Always read the instructions that come with the system you buy and follow them regardless of what we suggest. The main thing to look out for with spray foam systems is the temperature of the material your spraying and the temperature of the van when you spray it. For the DOW FrothPak system they recommend getting both the material and the surface you're applying it to as close to 75 degrees F as possible. If you are below this temperature you will not get as much yield out of the system. That means that the spray foam will not expand properly, and you will not get as much insulating value when you spray it. In order to warm our tanks up we put them in a cooler with hot water until the water temperature stabilized at 75 degrees F. When it was time to spray we removed them from the cooler and agitated them by rocking them back and forth.
Humidity also plays an important role when applying spray foam insulation. Polyurethane closed cell foam contains two separate chemicals that are mixed together when sprayed. The reaction between the A and B chemicals is an exothermic reaction. This means that heat is released as a function of the reaction. If the humidity is high, this can cause condensation to build up on the panels you're spraying while you spray them. The reason this is a bad thing is that if there's condensation on the panel and you spray over it the water will become trapped between the foam and the metal. This creates an opportunity for rust to form on the inside of the van wall and eat it away from the inside. If you don't have a climate controlled shop to spray foam in where you can control the humidity, wait until a good weather day with low humidity.
2) Spraying the expanding foam insulation
Now for the fun part, actually spraying the foam into your van. Before you even crack the valves open on the material cylinders make sure you have on the proper protective clothing. Our kit recommended a full Tyvek suit with boots and hood, along with eye protection and a respirator. The foam does use a chemical reaction when it expands and it's important to heed the safety warnings of the kit that you purchase. We looked like astronauts in there spraying foam, but it was definitely worth it to stay safe during the application process.
The key here is slow and steady wins the race. We've already talked about how spray foam creates an exothermic reaction but let's dive a little deeper into other reasons why that matters. When heat is generated on a metal surface then pressure is applied due to an expanding spray foam, distortion of the metal panels can happen. We've seen pictures of vans for sale, and you can clearly tell they were spray foamed just by looking at the pictures of the outside of the van. In order to avoid this you have to limit the amount of foam you spray onto the surface of the van at a time. We aimed to get around ¼ inch of spray foam on our first pass and this worked really well for us. Once the first layer on the entire van expanded out, we applied more spray foam with a second and third pass. This also helped ensure that the spray foam insulation would cure properly.
Another thing to keep in mind as you spray is the order in which you attack different parts of the van. We started by using the conical nozzle on the spray gun and shot the wheel wells first as a test area. Next we moved to spraying the hard to get areas behind the metal ribs of the van. We did this because while spraying the large flat panels, the openings to the ribs became covered by expanding foam. The next step is where we would do things differently. Instead of leaving the conical nozzle on the spray gun, we would switch to the fan nozzle in order to get more even coverage as we shot the roof, walls, and floors. The conical nozzle worked, but we ended up with a less consistent pattern and had to do more cutting once the foam cured.
Our last piece of advice during the application portion is to spray your way out of the van. Basically do the van floor last and use a consistent pattern. Try not to jump around from place to place in the van. If you start in the front on the ceiling, then make a complete first pass in the van and return to ceiling in the front of the van for the second pass. Follow the exact same path as the first pass, as this ensures that the foam has time to expand and cool before the second pass is added on top. It's important to note that when you are spraying foam insulation into the door panels of the van that you avoid getting spray foam on the door latches and handles. Once you complete the doors, walls and the ceiling, then come back and do the same process on the van floor if you're choosing to foam the floor as well. We just stood on our wood floor supports as we shot the foam into the floor cavities. We applied it a little thicker on the floor because we weren't concerned if the panels under the van deformed a little bit. This made the floor portion go faster.
3) Clean-up
The clean-up portion of the spray foam insulation process is probably the most time consuming. The more consistent and level you are with the application of the foam, the faster this part will go. We ended up having to do quite a bit of trimming because we didn't switch out the spray tips on the gun. There's three main ways to get the foam down to the levels that you want it in order to install walls, ceilings, and floors over it. We used a 24” wood saw like a bread knife to shave the foam down flat to the framing. Another method you can do is use a putty knife to scrape it off of the areas you don't want it. These two methods make the least amount of mess, but still require a fair amount of clean up. If you want a faster method (but a more messy way) to get the foam down flush with the walls, you can sand the foam down with a disk sander. Doing it this way makes a really fine dust that will get everywhere. Also if you choose to go this route, it is very important to have a respirator on while sanding. No matter which method you pick you'll have to do some vacuuming and eventually blow the van out with compressed air to get all the particles out.
All in all if we had to do it over again we would use spray foam insulation in our next van conversion. While the cost is on the higher side, it offers unparalleled thermal insulation when you compare it with other methods for camper van insulation. We also liked the fact that we could spray it into the entire van in under two hours. When it comes to camper van insulation, we are personally a fan of closed cell spray foam insulation and we hope that this blog has answered any and all of your questions on the topic. If you're still not sold on the process of covering your sprinter van in spray foam and want to do some more research on camper van insulation check out our blog comparing the different ways to insulate your van.
Want to watch our spray foam process?
Our YouTube channel covers our build process in weekly videos. Episode 12, shown below, covers our closed cell spray foam process specifically in more detail. You can watch our steps of setting up (learn about what we regret not setting up), watch us spray, and watch us clean-up for hours (without having to watch for actual hours of course).
