Part 5: Insulation
To insulate or not to insulate? That is the question! Or so it seems to be one of the biggest questions that is debated when building out a van. Not to mention, if you decide to insulate, the myriad of options that lay at your fingertips. Let's dive in to the world of fiberglass, foam board, fill, and so much more.
What I did, what I used, how long it took, and how much it cost?
For me, insulation meant insulating all of the walls, doors, and the ceiling in the main living compartment (which means I did skip out on insulating the floor). For the ceiling I used some sound deadening material, 1” polyiso foam board, and Great Stuff. On the walls and doors I also used sound deadening material, but for the main insulation I used 3.5” fiberglass batts and some Reflectix to act as my vapor barrier.
Installing all of the insulation on the walls, ceiling, and doors took about 32 hours of working time. Splitting that up, I’d stay it was about 12hours for the ceiling, 16 for the walls, and 4 for the doors.
All in, insulating the van cost me about $380.
Why I did it (including counterpoints)
Polyiso Foam Board & Great Stuff for Ceiling: Okay, where to begin with insulation. There are many different kinds and they all serve different purposes. In general they’re rated based on their R-value which tells you how well a material insulates something. Higher the R-value, the better the insulation. There are other factors such as durability, malleability, cost, subsequent energy efficiency, moisture resistance, etc. I’ll let you dive down the rabbit hole like I did on that, but in my opinion, R-value and usability for your application are most important. So for example, I wanted to keep as much height to the ceiling as possible, and subsequently, I went with a 1” polyiso board for insulation as it is very dense, and consequently delivers a pretty decent R-value of 7 or 8 even though it’s pretty skinny (in comparison to a large batt). I could have gone with some other foam board materials such as EPS or XPS but polyiso delivers the best R-value of the foam boards when compared against the same size boards, so knowing I wouldn’t be using much on the ceiling in order to not cut into the ceiling height much, polyiso was the way to go. On the ceiling there are sheet metal ribs which one cannot really feed the rigid boards into, therefore I decided to fill these ribs (nooks and crannies) with Great Stuff expanding foam. At the time it seemed like a good idea and I think ultimately it did serve its purpose but as you’ll read later we found a better approach when we moved on to the ribs on the walls.
Fiberglass Batts for Walls and Doors: Unlike the ceiling, size was not at a premium as the ribs on the walls were rather deep. Therefore, in order to make it easy on ourselves (batts are more malleable and easy to use that rigid foam) and save some money (batts are much cheaper than boards) we went with fiberglass batts. Within the ribs for the walls, unlike using Great Stuff like on the ceiling, we decided to cut thing fiberglass batts and feed them through cavities in the ribs. This ended up working out much better than using Great Stuff and if you have the option to feed fiberglass or loose fill into hard to insulate places, I’d recommended over Great Stuff, provided you have a Vapor Barrier to cover. Which leads me to my next point…
Reflectix for Vapor Barrier: For those new to insulation, depending on the application you may need a vapor barrier that sits outside the insulation on the side that’s adjacent to the inner wall. The basic idea here is that inside your van, you will be living, breathing, perspiring, etc. and that vapor on the inside of the van could seep behind the walls into the insulation, hit the cold outer wall of the van, condense into water, and then begin to dampen your insulation. Over time, if enough of this happens you can rot or mold out your insulation, so that’s why in this case you need some sort of vapor barrier that will prohibit vapor from reaching the insulation. On some insulation, like the polyiso boards, there is already a vapor barrier built in (usually a layer of aluminum foil) so you’re all set. In the case of fiberglass batts this is not always the case however, so what we decided to do was use a layer of Reflectix to put over all of the wall insulation to create a vapor barrier. This worked like a charm, because it meant we more or less had a continuous vapor barrier with very few seams. You still want to patch over the seems with foil tape, but we’re talking about vapor here. The tiniest of holes will let vapor in through to the insulation. The Reflectix cost us a bit more, but it’s nice to know that we have good protection for our insulation, because if that starts to mold you’re looking at quite the operation to remove it once the van is completely built out.
Sound Deadening Material: Lastly, we decided to add on some sound deadening material behind all of the insulation. The walls and ceiling of the van are just sheet metal which tends to vibrate and rumble so putting in some of the material helps limit that road noise while driving as well as keeps things a bit quieter on the inside and outside.
What went well
Insulation!: I happen to be writing this post after I’ve already been in the van in some cold temps (multiple nights in the 40s and eve one or two right at freezing) and I have to say this stuff really seems to be paying off. When I started thinking about insulating I was really hesitant about it because any part of the van that you don’t get covered in insulation essentially becomes what is called a cold sink, which means it’s just a huge hotspot in your van for cold air to pass through and ruin all your other insulation. Well, I’ve found now that while that is true, as long as you insulate the majority of the vehicle well, not covering every spot is not going to ruin all the other spots you did cover. If the temp is set not to drop below 40 I usually still go to bed just in my undies and cover with a quilt and one other blanket, and I’m still nice and toasty. I even bought a thermometer and on nights like this, it looks like the van stays right around the high 50s or low 60s - not bad at all! When the temp is set to drop around freezing I just put on some sweats, wool socks, and a sweatshirt and I still sleep with just a quilt and blanket comfortably. This was in the alpine so not consistent cold (would usually get to around 70 during the day), so I’m interested to see what happens when I take it somewhere that’s always cold. Either way though, I’m convinced - insulation is totally worth the hassle!
Sound Deadening Material: Again, since we’ve been in the van for a few weeks already, I’m amazed at how quiet it is at night (I’ve never woken up to outside noises and we’ve parked in countless 24 hour Walmarts, next to highways, and a stone’s throw from a train once) and also what it seems to be doing for keeping our voices muffled at night. We can be in the van playing music and talking comfortably and you can’t hear a thing from outside.
What didn't go well/What I might’ve done differently
Great Stuff: Expanding foam definitely has it’s applications and uses, but I have to say insulating part of your van upside down is not one of them. We used it to try to insulate the ribs on the ceiling by piping it into the open cavities, but it was just too hard to get a feel for how much to place in the cavity. At first we loaded it in but then we had to sit there and clean up the excess for nearly an hour as it expanded out of the ribs. In our next attempts we tried to limit it, but then there wasn’t any excess coming out of the cavity so we were concerned there wasn’t enough in there! At the end of the day, feeding batt insulation or loose fill seemed to be easier to work with, cleaner, and got the job done just as well.
Compressing the Fiberglass Batts: In using fiberglass batts on the walls there was often times that we would run the batts across some of the ribs or parts of the wall that were not the same depth as the majority of the wall. This ultimately left us needing to compress some parts of the fiberglass batts in order to sure up the walls later. If you do some research you’ll find that fiberglass batts lose their insulation properties if you do not allow them to expand to their full size (so for example, if you have a 3.5” batt that gives you an R-value of 13, if you compress it to 2” you will achieve an R-value of less than 13). It’s unclear to me how much this affected the overall insulation of the van (I think the only way to tell would be to heat map the van using infrared) but it’s just something to consider when you decide to go for foam board or fiberglass. The rigid foam board cannot be compressed as its rigid therefore it sort of forces your hand in a good way to use the appropriate amount in each spot, but this of course takes more time.
Build tips
Cutting Insulation to Custom Sizes and Shapes: Be sure to buy some sort of serrated knife to make it much easier to cut the foam board and fiberglass to size. And while you’re at it be sure to get either some cardboard or paper as well as a scribe tool to help with marking custom cuts. Vans have a tone of crazy nonstandard shapes (especially in corners) that you have to work with, so it’s best to get your practice in now with foam board and malleable fiberglass batts because later you’re going to have to do it with much more rigid materials like wood, not to mention the fact that everything will be able to see your craftsmanship!
Foil Tape: Thinking back to vapor barriers, be sure to get plenty of foil tape to help cover up any seams in your vapor barrier. I think we went through 4 or 5 rolls of the stuff because you often have to go 2 or 3 layers to make sure it sticks well.
Spray Adhesive: Spray adhesive is your best friend during insulation. We used the 3M Super 77 on just about everything just to make sure it sat in place nicely as we installed it and while we waited to get the walls up. On the ceiling we even used 3M 90 which might as well be as strong as liquid nails when it comes to putting up insulation.
I know that was ton on insulation but there’s so many options and ways to go about it, so I felt like I had to cover as much as I could! Hopefully you find it useful. Next up, electronics!
