Yesterday, I sprayed expanding foam insulation onto the ceiling and walls of my bookmobile conversion and posted about it on my conversion thread
. I figure this might be something other converters are interested in, so I'm going to share my experience on this forum.
I bought a Foam It Green 602
kit from Guardian Energy Technologies (Made in USA;
online at http://www.sprayfoamdirect.com
). The cost of the kit was about $750 with shipping (the compressed nitrogen requires HAZMAT charges and the two bottles of chemicals are quite heavy), but that expense is much
less than having a professional residential insulation company do this job. I priced out the cost of having it done and for my little bus (living area less than 200 square feet) it was over $1600. In my research I found that even the professionals will recommend doing it yourself if your home is under a thousand square feet or so. This kit is supposed to cover 600 square feet with a layer of foam one-inch thick.
The kit comes with everything you'll need, except some kind of respirator. While the foam doesn't give off any toxic fumes (I didn't detect any smell at all), the particles in the air can be hazardous if inhaled, so make sure to wear something over your mouth and eyes. Goggles, gloves, booties, and a hooded Tyvek suit are included. While the instruction recommend wiping the face of the goggles with a little petroleum jelly (included) to prevent the foam particles from sticking to the lens, that just makes it too hard to see what you're doing. I tried wiping on the jelly and then wiping it off to hopefully leave a residual amount on the surface, but that didn't work. After I was done, I thought of what would have been a great solution: Wrap the lens with a little Saran Wrap and then replace it to clean the lens. Man, I wish I would have thought of that before I started.
Spray foam protective gear
You'll need to mask off anything you want to protect from falling foam drips, including the floor. I recommend doing this before you've installed the final flooring. (In my case, the vinyl flooring I was working over is not the final covering and is only there as a water barrier in case of a leak in my fresh water tank which will be under a raised platform inside the living area, so I didn't worry about the floor.) Large blobs of foam will collect on the nozzle of the spray gun and drop to the floor with a splat. It's impossible to avoid stepping on them, so wear the booties while you work. The blobs are sticky for a few seconds and the foam cures in a couple minutes, but they turn to dust when you crunch down on them.
The instructions couldn't be easier, so I'll leave you to read them on your own if you get the kit, or watch any of the training videos on the company website. Once you get started it takes only a couple minutes to get the hang of it, although I constantly had to remind myself to release the trigger safety when I started to spray. It's not exactly the most user-friendly arrangement, but I suppose it does its job and keeps you from spraying all over the place as you handle the hoses and gun.
The bed area in my bus is a little tight and required insulation on five sides, and I had to spray a little foam under the bus in an area that wasn't already insulated from the coachbuilder factory, so I had to work in some pretty uncomfortable positions. As a result, the nozzle was perhaps a little too close to the surface in some spots for a smooth coverage of foam, giving it a "corrugated" look where the foam was laid in overlapping lines. If I had been able to shoot from a little further away, the spray pattern would have spread out a bit more and that makes for a much smoother application. On the parts of the ceiling where I was able to stand on the floor and work over my head, the insulation is much nicer looking. You really can't spray this thinly onto any surface as the foam needs to heat up to cure (and it does get hot). At least a third of an inch is required to allow the foam to insulate itself and generate enough heat for the process, but too much can also be bad; according to the instructions, spraying a layer four inches thick could generate so much heat that combustion could result. I often found that a large blob from the nozzle that found its way to my finger would be irritatingly hot for a few seconds. I could easily feel the heat coming from the foam in places where I held my hand a few inches from the curing process.
The instructions warn to remove the spray nozzle if you're going to pause the spray for more than 30 seconds, so you have to keep moving. They do provide ten nozzles in the kit, so unless you're doing a very large area, you should have plenty of nozzles for a lot of stops. (I used only five nozzles, taking breaks to cool off and to move from underneath the bus to inside it.)
I mentioned that I was under the bus for part of the job and this brings up another point: It is recommended that you cover the insulation with some kind of protection if it's in an area that will be exposed to direct sunlight or weather. All of my interior foam will be inside the walls, but the foam under the bus will have to be protected from water and road debris as I drive, so I'm going to spray it with a layer or two of rubberized undercoating just to be safe.
The foam starts to rapidly expand about seven-to-ten seconds after application, so you'll need to watch it closely if you have anything in the bays in which you're working. In my walls there are many runs of blue "Smurf" tubing conduit for the wiring. I had to hold the conduit in place for a few seconds to keep it from being pushed out beyond the surface of the wall studs. Once the foam was tacky, I could move on to the next area. I was also fortunate to have a lot of leftover styrofoam boards from the original interior and wanted to re-use as much of that as possible. The same technique applies: Hold the boards in place or the expanding foam will lift the boards out of the stud bay and then you'll have to shave down the styrofoam in addition to any squeezeout from the expanding foam.
I haven't yet got around to shaving down the squeezed out foam and I've been pondering how to go about it. I could just use a long reciprocating saw blade, but there are available tools made just for this application. They're called "foam saws" and they look a lot like a regular recip saw, but are lighter and smaller. Apparently, they also have a proprietary blade attachment, so you can't just get one of these extra long blades (up to 36") and snap it into your Sawzall. That would be too handy.</sarcasm> I'll try the recip saw blade first, since that's what I have, but I might end up making a special tool from a long bow saw blade mounted parallel to the surface so I can get nice and flush with the cutting action. I'll update this thread when I figure out what works.
The result is an interior that should be extremely efficient as far as heating and cooling goes, and all the parts of the bus are now tied together very solidly. When I close a door, there is no more rattling of metal-on-metal in the ceiling or banging of studs against the outer skin of the bus. This is the main reason I wanted to use this kind of insulation. I have more insulation in the bottles, though I don't know how much remains. I want to spray what's left onto the ceiling of my underfloor battery compartment as that's the only part of the interior floor that wasn't insulated while the generator was originally installed.
I would like to say I made a video of this process, but it was just too much of a mess to risk having my iPhone inside while I worked. I did get some pictures, though:
The ceiling over the bed is rippled with foam as I was fairly close while spraying and you can see where the styrofoam boards lifted as the foam cured
You can see how the ceiling insulation is fairly smooth because I was shooting from further away. I'll be adding fiberglass batting in between the joists for even more insulation in the ceiling. Filling those deep bays with the expanding foam would have required another 602 kit
If you have any questions or want to add your own experience, please post them here so others may also read and learn.
EDIT (25 APR 2013):
Picked up one of these today: Stanley FatMax Reversible Flush Cut Saw
, $12 at Lowe's. It's perfect for cutting off the foam squeeze-out by the studs. I tried it out tonight before it got too dark to work and will finish tomorrow, but I can tell already that it's just what you'll need for trimming the foam, and much
cheaper than a dedicated electric foam saw. The reversible feature is great for getting into corners of all angles, too.
EDIT (26 APR 2013):
So I finished trimming all the squeeze-out and it wasn't that bad. The saw I used was great for knocking down the large chunks, but the bed platform was a special case that required a special tool. Since my bed is going to be on this surface, I want it to be as flat as possible. Any insulation between the platform joists needs to be no higher than those joists to avoid hills in the plywood that will be laid on top of them. I used a random orbital sander (with a vacuum attachment) to flatten the uneven surface and it worked like a champ. It's not as fast as the saw, but it does a much finer job of removing small amounts of foam. And with the vacuum attached, it's also much cleaner than the saw. Finished results:
The hand saw leaves a rough cut:
The sander leaves a very smooth surface:
Bed platform foam finished: