Done for now, at least.
I also finished the first layer of ceiling insulation and installed the furring strips for the second, "almost-continuous" layer of insulation.
Done for now, at least.
I also finished the first layer of ceiling insulation and installed the furring strips for the second, "almost-continuous" layer of insulation.
I've been focused on insulating the trailer and the end is in sight.
As I'm planning on mostly boondocking in the mountains and deserts of the southwest, I've got to make this thing habitable in extremes of heat and cold with no option for plugging in to grid electricity. That means no A/C and no traditional RV gas heater.
So I need to insulate it well. In a perfect world, my body heat will be enough to keep it survivable through a cold night. What do I mean by survivable? If I can keep the interior air temperature above freezing on a 0*F night, I'll be happy.
My strategy for summer is to have fans, excellent roof insulation, a good outside shade hang-out area, and the ability to simply weigh anchor and move to higher elevations if it gets too unbearable. I'll consider small, portable swamp coolers, but most of the ones I've seen seem pretty poorly made. (It's important to note that I'm planning on being in warm humid climates approximately never. The design decisions I'm making are very much driven by an arid-only assumption.)
The first and most important thing to understand about insulating structures is that heat likes to cheat. If you stuff the cavities with insulation but your outside surface is aluminum and you have metal studs, the heat is basically going to ignore your cavity insulation and go straight through your studs. This is called "thermal bridging".
In September, in Santa Fe, I had just put up wall cavity insulation. The metal stud was literally too hot to touch. In order for this trailer to be remotely habitable in warm and sunny weather, it needs to somehow insulate these thermal bridges. So in the walls and ceiling, I will have two layers of insulation: cavity insulation, and a mostly continuous layer of insulation that covers the studs and ribs.
For the floor insulation, it's a little trickier. I don't want to add continuous insulation below the floor joists, because I want to maintain my ground clearance. And I don't want to put continuous insulation above the subfloor, because then I won't be able to stand up straight inside. If I had a taller trailer I would definitely do indoor continuous insulation... but if I had a taller trailer, I'd get worse gas mileage and have more wall area to transfer heat, so my thermal performance might even be worse. It's all a trade-off.
I decided to do 2" cavity insulation and then use pipe insulation to cover the joists. This will help mitigate thermal bridging in the floor.
I used polyiso insulation because that's what my local hardware store has. In retrospect, the foil is very thin and clearly won't hold up to thrown rocks as well as XPS. Once the foil is damaged, the exposed polyiso will be vulnerable to moisture and just powderizing and sort of falling apart.
If I had it to do over again, I'd use XPS because it just seems tougher for this use. That said, I don't expect this to be a significant issue. I'm not concerned about moisture damage because I'm almost always going to be in arid regions -- even if it does get wet during a storm, it'll dry out almost immediately. And as for the rocks tearing the insulation up, I'll just keep a roll of foil or duct tape handy and inspect it often. If it gets real bad, I'll protect the insulation with some other membrane, but I suspect I won't need to.
To secure the insulation, I dropped bolts from the subfloor above and snugged it with a metal strap.
A possible bonus of underbelly insulation is that it might improve the areodynamics of the trailer, and thus improve my gas mileage. Every little bit helps.
When I can't work on the trailer physically, I try to plan ahead by working on it virtually. Here are a few recent renderings, representing working through ideas for the finishes for the trailer.
So Greece was nice.
I'm now back in Walkers Pass on the family land, picking up the threads of trailer construction that I had left off at the end of September.
The first few days back at work mostly consisted of me leaning against a wall, staring at the ceiling, attempting to figure out what parts I need that I don't have and in which order to do everything.
My first priority is to get the insulation complete (winter is coming, y'know). In order to do that, I need to get all of my roof penetrations sorted - solar panel wiring, skylights, and vents. In order to do that, I need to decide where all of my interior walls are going to be. And on and on.
Finally I said "screw it!" and did the only logical thing - I cut two holes in the roof.
These will feed the solar panel wires and roof-mounted light circuit.
Since I was on the roof, I ripped out the old static vent and replaced with a fantastic fan.
I'm also insulating the ceiling cavities.
Okay, that about gets us caught up to the present moment.
I'm writing this right now instead of working on the trailer because I went out this afternoon to do more insulation, cut my last piece of insulation incorrectly, twice, and then the wind blew my ladder over and smashed the windshield on my truck. Okay universe, I get it, today is not a work day.
This week we drove from Santa Fe, New Mexico, to Walkers Pass, California. We overnighted in Flagstaff.
We were driving into a ripping headwind the entire way. On flat road, I could get the truck up to 65 or 70mph, but any slight hills + headwind meant I was doing good to maintain 55. This isn't very safe on I-40 with the semis blowing past us, so I looked for the first opportunity to get onto back roads.
At Gallup we got off I-40 and drove through some of the most beautiful desert I've ever been in. We spent the night in Flagstaff, and got back on I-40 as far as Needles. I knew that the freeway had some major hill climbs from there, and the wind had picked up again, so we ditched onto a big detour through the southern Mojave desert.
Finally we made it to Walkers Pass without incident.
The trailer will stay here while we're in Greece for the next two months, and when we return I'll finish it here.
All 500w of solar panels are now securely bolted to the roof.
A bonus of the panels is that they shade the roof and really cut down on the amount of heat the insulation will have to protect the cabin from.
I got the first 250 watt solar panel mounted on the roof today.
No rocket science going on here, just screw the ladder racks on...
And bolt the panels to the ladder racks with some mounting brackets from Renogy.
One more to go in the front.
So in my last post, I put electric brakes on my trailer (along with the new axle). Those won't do much good unless I have some way of telling them to brake when I want them to while I'm driving. Hence, I installed a brake controller in my truck over the past two days.
2000 Tacomas didn't come with a factory tow package, so I had to dig around under the dash to get all the right wires to the controller and to the plug in the back.
While I was at it, got all the wiring in place for the trailer-mounted backup cam, with a switch in the dash so I can manually switch between the truck and the trailer backup cam.
I also got fed up with all the slapdash chassis grounds I had going on at the rear of my truck, so I ran a 10awg wire directly from my battery to a marine-grade bus bar, and grounded everything to that. My cam no longer flickers when I have turn indicators on.
I tested the brakes today and they seem to be doing a fine job of stopping the trailer. Probably a bit more tweaking I need to do but for now, I feel good that my trailer isn't going to push my little truck through an intersection.
Now for something completely different: swapping the axle and adding electric brakes.
The original axle was a "drop" axle, meaning the spindles (the bit the wheels bolt on to) are about 4" higher than the axle beam. This is a good thing for normal cargo trailers because it's easier to get heavy stuff into a lower trailer.
I, however, plan on taking this thing on rough off-pavement roads, and don't like the idea of scraping my back end on rocks every time I take a little dip. So I bought a straight axle, as well as some brakes, and swapped them out yesterday.
The inner walls are complete.
It is noticeably less hot inside, although still not comfortable since the ceiling is still exposed sheet metal and too hot to touch when in direct sun. There are a few steps in between now and ceiling insulation, though, so I'll have to wait to see just how much heat gain my insulation scheme will cut.
It is thunder and lightning-ing out, so I'm taking the time to catch up on the build log.
Two weeks ago I insulated the wall cavities and put the original plywood back on.
Now, as any decent mechanical engineer will be able to tell you, those metal studs conduct a lot of heat through the walls. I put my hand on the horizontal metal ribs in the nose of the trailer when the sun was shining directly on it, and it was so hot I couldn't hold my hand there for longer than five seconds.
This means that cavity insulation by itself does precious little to actually insulate a metal-framed structure. Letting heat in is bad enough: the real terror is the condensation issues you can get inside your wall assembly when it's cold out (think mold, rot, rust, etc).
Long story short, the walls are only half done. I'm adding another layer of continuous insulation to the inner walls.
The somewhat odd placement of the panel is to reduce visible seams - the bottom seam will be covered by a bench, and the left-most seam will be covered by a shelf.
Most trailer builders would probably recommend furring strips to affix the panel to the wall, to make the surface very smooth. This is good advice, but those furring strips are just heat fins to me, so I'm giving this route a try. The panel/insulation sandwich is screwed into the 1/2" original plywood with decking screws every 6" on 16" center, it feels very firm, and the surface is actually rather consistently flat.
The rest of the wall insulation should go up quickly, and then it's on to other exciting things.
Playing a little bit of catchup here. Last week I got the floor in and the rear door insulated and sheathed.
Then I was in California this week for work, got back last night. Today I got the floor screwed in to the frame, the rest of the wiring for lights, fans, and outlets done, and caulked a bunch of holes and seams.
Then it started raining, so I came inside and finished most of the rest of the toilet. I more or less just followed the excellent article these folks wrote about their RV composting toilet.
The only things remaining are the vent van, urine bottle, top lid seal, and paint.
Yesterday I finally applied two coats of POR-15 rust prevention paint, which, when done right, is just about the strongest anti-rust coating you can put on metal. I should have zero issues with rust whatsoever from here on out.
This has been a week of mostly awful work, crawling around on my gravel driveway under the trailer, smearing toxic chemicals on rusted metal 2" from my face. And while it doesn't look like much has been done, I'm going to sleep a lot better knowing that I just don't have to worry about the frame falling apart on me years down the road.
I wire brushed the plywood floor panels and coated them with boiled linseed oil to protect them from moisture and also from dry rot.
And the composting toilet is coming along nicely:
Here are a couple more renders showing the layout a bit better:
It's been about a solid week of stripping the paint from the frame, which consists of crawling over and under the frame slathering on Citristrip (a chemical paint stripper), peeling it off with a scraper, and then wire brushing the residue. Today I finished with all that, and will start the process of coating the frame with POR-15 (a heavy duty 'paint' / rust converter) tomorrow.
Also today I went on a road trip up 285 to Salida to pick up my solar system from a guy who sells systems to vandwellers and RV'ers when he's not hanging out in India. He gives you all the parts you need, down to the wiring and lugs, and provides a diagram for you to install it yourself. Being a bit of a dunce when it comes to electricity, just having to figure out which parts go where and try not fry myself is going to be a huge time saver.
I'll get (way) more into the details later, but it's 2 250w panels, and 4 90AH AGM batteries, with a 1000w inverter.
I've been on a road trip the past two weeks, so no actual work has been done.
I have been ordering parts and materials like mad and generally trying to have everything in order so I can hit the ground running when I get home. Time is of the essence.
I made these test renders to figure out what materials we want to go with, if we have enough windows, and get a sense for if it is going to feel too much like a coffin.
I also made a Youtube 360 video. You can pan around with your mouse, or use your device to look around the trailer.
Last week I installed a transmission cooler in Jeremiah (the truck), which will help the transmission handle the increased load. I also installed a backup camera and monitor so I can connect to the trailer hitch without assistance if necessary (that's really a feature for our relationship, which you'll know if you've ever tried to connect a truck to a hitch with 'guidance' from your significant other before).
I'll put a camera on the back of the trailer, too, so I don't back it up into a cow or something.
All of the wall plywood and floor plywood is now out. The only bits left are the two doors, but I'm going to leave those for the moment.
The frame rust, now that I can see all of it, really isn't as bad as I feared. I'll wire brush it and do the POR-15 rust treatment so this trailer can stay on the road for years to come.
Also, I picked up the tow vehicle on Wednesday:
Taking the plywood off requires the use of a nail puller to rip the screw/nail things out. I got about half of it pulled off tonight.
The process rips the 1/2" plywood up pretty good, but no so bad as I won't reuse it.
The rib rust actually isn't as bad as I thought, mostly just in a couple places. It will be pretty easy to mitigate and Rustoleum over it.
I've been doing a lot of research on insulation strategies: spray foam, mineral wool, batts, polyiso, XPS, EPS, radiant barrier, etc. For a variety of reasons, I've decided that polyiso is the least bad option. (I really wanted to use Roxul's rock wool rigid board product, but that stuff is so heavy it would completely blow my weight budget).
I also got a quote for my solar system ($1,200) from a guy up near Denver who sources a bunch of his stuff second-hand or canceled orders, etc. He designs the whole system and provides all the various parts, so that's going to be a huge relief in terms of the time I'd have to spend figuring everything out, sourcing every component, etc.
First day home for longer than 8 hours in a few weeks, so I took the opportunity to get into the trailer and start ripping stuff out. I pulled all the thin wood stripping out and tried (and failed) to start taking the plywood off.
I failed to get the plywood off because they're fastened with whatever these are:
They don't screw out, so I guess I'll have use a nail puller on them.
Also I discovered that the studs have significant rust issues as well. I'll have to take all the plywood off and address it as well as the underbelly rust.
First pass at the rough design model is "done", meaning I've got enough of what I want to do figured out that it's time to start actually doing stuff and see what's reasonable.
From the rear to the front: benches and table that collapses into the bed. Storage, water tanks, and solar system will go in the benches.
Kitchen has a gravity-fed sink (a footpump will get water from the main tanks to the gravity tank above the sink), and moveable 2-burner propane stove. Greywater tank under the sink.
Storage shelves opposite the kitchen counter.
DIY composting toilet at the front.
One of my main obsessions/challenges is figuring out how to insulate this thing without sacrificing inner dimensions:
This is showing 1" cavity insulation, with another inch continuous insulation on the inside of the plywood. Finish wall paneling over that, with metal strips to hold it all in place.
I'm trying to figure out how to eliminate thermal bridging through the floor framing members. I came up with this idea to 'cap' them, and then fashion some sort of metal undercap to hold everything in place. Might be overkill.
Further refinements to the model will continue through the project as I need to figure things out.
Time to move to phase 1.
I bought a 14' Cargo Mate Blazer trailer off of craigslist and rented a uHaul trailer to get it to my driveway in Santa Fe.
Inner dimensions: 12' 7" long, 5' 8" wide, 6' 2" tall.
I'm going to be out of town for something like the next 2 months, so very little actual work is going to get done on it till mid July. I'll be mostly developing the design, sourcing materials, etc until then.