Now that its insulated we can start building the interior! Its been a lot of work to get here, but there is so much more to go.
For the interior walls we are using a 1/4″ plywood, its prefinished birch. Reasonably cheap, just cut and install, not finishing needed. Its not the lightest, but works well. To install I used more construction adhesive (i think there are 9 quart tubes behind the walls and ceiling!) and micro pin nails. I’m happily surprised the nails hold really well.
I started with the easy square one…. Good practice anyway! I will come back and cut the windows from the outside with a router, this way the inside and outside holes match perfectly.
All these were cut with my old skill saw and a jog saw. Nothing fancy. I did my best to break the panels on windows, that way there were no seams running right net to them.
With the sides done we can install the windows. Ran into some issues here. I should have used a wood strip around the windows, not just the foam, this would have kept the correct wall thickness. I ended up having to shim the interior plywood out to make the walls the required 2″ for the windows to clamp too.
But with the windows in we are starting to get somewhere!
Windows were a big step. Tons more light and feels way more open. Ceiling goes in next.
I made a quick time lapse of the weekends work. There are some previews of what’s to com in the next post as well.
The walls are bare aluminum, there is a rib every 12″ that is one inch deep. We need a couple things here, 1″ is not enough insulation, we camp in sub freezing a lot and more is better. Also we need something to attach the inner skin of the wall to. Also a vapor barrier is needed to keep the wall cavities dry and to keep the mold out.
So to do this, I cut strips of 3/4″ plywood down to screw and glue to each of the aluminum ribs.
This will give us 1 3/4″ of insulation, we are using polyiso spray foam, its R6.6 per inch, that will give us about R11.5 in the walls. The spray foam is also a very good vapor barrier, so we get a bonus there too.
The strips were glued on with construction adhesive and self tapping screws every 12″. They are quite solid. 1/4″ plywood is going to be used for the interior skin.
The ceiling (which apparently I didn’t take any pics of, will get 4″ of foam. I used 1/2″ plywood and 2″ foam board strips to furr it down. The ribs on the ceiling are much larger.
Everything you don’t want covered with foam gets covered, all the wires get taped down, and attached wherever possible. If not the foam can get behind them and push them off the wall. it goes on as nearly a liquid and expands as it cures.
I looked at doing a DIY spray foam kit, I have used them in the past, but this is large enough I would have needed two kits, its messy and just an all around pain. I decided to hire an insulation contractor to spray it. Money well spent IMO. If you do use the DIY kits, find and old cooler that the tanks fit in, and fill ti with very hot water, they work best when the tanks are above 70 ish degrees.
Getting ready for insulation was a lot more work than I expected…. Everything that goes inside the walls has to be in place. Once the foam is in there is no changing or adding things. I had a big list.
The insulation guys showed up! They set up fans to ventilate and got to spraying. The two part foam expands and cures in place after its sprayed. Its closed cell, wont absorb moisture, and adds a lot of structure back to the truck, it glues itself on very very well….
Once they are done spraying, it looks like a very messy frosting job on a cake, then the dirty part starts, they grind it all back down flush to the furring strips we added. Two guys with grinders makes a lot of foam dust and chunks.
After grinding it smooth they came back to make sure no spots were too thin and nothing got missed. It immediately made it not sound hollow inside any more. I need to come back later and insulate under the floor. Its something I will do myself later on.
We ended up with R 11.5 in the walls and about R 28 in the ceiling. Its nicely insulated.
Now that the truck and box are connected its time to make it feel more like a livable space, I need windows! The windows were ordered from Motion windows. They will make any size or shape you need. I ordered all of them double pane, this was the big one for me. A bit of insulation value and they don’t fog/drip quite as much. They all also open, and have screens, which should help a bit as we don’t have any AC.
I started with the Door, it was an ebay special, lots available there, but the UPS guys definitely had their way with it. It will still work, just some dents around the edges.
Hole was cut with a skill saw on the straight parts and a jig saw for the curves.
Door was installed with polyurethane caulk and stainless screws. Gives some scale to the truck. That is an 8 foot ladder…..
That was the easy one, now onto windows. The windows have a 3″ corner radius, I used a 6″ hole saw to make the four corners, then connected the holes with a skill saw for the straight lines. They are sandwiched together with the inside panels, so I can only temporarily install then before the inside is done.
The tape keeps the window in place and the water mostly out. There is one big window where the dinette is, one in the kitchen, and one above the bed. Hopefully that’s enough venting. I wanted as much natural light as possible, but had to balance cabinet/storage space as well.
Two windows you can see here, and a little preview of the next chapter, furring the walls and ceiling in.
We left off with a big new hole in the truck. Plastic works to cover it, but not exactly what we are going for.
So A gasket was ordered, its a rubber accordion shaped seal, its made to slip over a lip on either side. e left a lip around the hole in the box, that as easy, but we need to fill in the holes where the window was, and shape a lip around the back of the cab.
A little CAD (cardboard aided design) and we have templates for the window. I used the piece of the back wall cut out of the box, it has ribs in it take make for nice strong panels and was just big enough.
They were cut using a jig saw and skill saw, then trail fit many many times, a little grinder work each time and finally they fit in place nicely. Some sealant and a few bolts hold them in place.
Now we need to finish cutting the hole, if you remember I left the bottom not done. This took some serious doing, I went trough four carbide tipped blades trying to cut that Little bit off.
Once that is cut and the window panels are in place we can start to fit the gasket. The gasket is from Uni Grip, they makes lots of different ones. Its made for a nice straight flange, I have the back of a cab wall, not straight or the right size.
The seal was glued in place with polyurethane caulk, after hammering it onto the lip all the way around it seems to fit well! We have a connected box and truck!
Cutting holes in a new truck is SCARY. But it needs to be done. One of the design requirements my wife and I had was being able to get between the cab and box without going outside. That means a big hole.
I started by striping the interior out of the back of the truck. This allowed access to the back wall and moving the headliner forward. Seats out, trim pieces out, seatbelts out, there are a lot of pieces in a new truck.
Once all that is out of the way, there is a lot of measuring this and that, thinking, staring at it, cutting holes cant be undone. We decided on a 3′ wide opening as tall as we could make it. Its offset to the drivers side a couple inches to allow a little more room for the passenger rear seat. Once the plan was finally in place, we drilled two holes in the bottom through both the truck and the box, this gave us the bottom corners. More measuring to make sure everything fit and its cutting time.
Starting from the box side I cut a big hole…. No going back now. A skill saw goes though the aluminum box easily. The floor not so much, its steel and really hard.
Once the hole was cut there it was on to the truck. I started by removing the window. I spent WAY too much time trying to get it out in one piece, I was doing great, it was loose all the way across the bottom and I only had about 8″ left to go on the top, when yeah it broke. Out comes the shop vac to clean up a lot of glass.
With the window out there was more thinking and tape measure work, and head scratching. Everything needs to line up on both sides. Get on with it, out comes the sawzall and I significantly drop the value of my new truck. But we have a hole! And it even lines up pretty damn well on both sides. The bottom lip will have to get attacked with different tools, its really hard and needs to get cut close to the floor.
Now that the roof is sealed up, I seem to have other places of water ingress….. The marker lights and something in the corners by the cab.
Marker lights are easy, but I don’t really know where the other water is coming in. A coat of sealant on the lights and we move on. Corners will have to be dealt with later.
On to forward progress, wiring design! This was kind of critical, once the insulation is in there is no changing it. I spent quite a bit of time thinking on electrical. I settled on batteries under the bed, I wanted to try to keep them a little warm as that was an issue in our old truck. We are using four 250Ah 6V AGM batteries, this should provide us with 250 usable amp hours at 12v.
So the forward edge under the bed became the main electrical hub. I needed to run both wiring for 12v, and 120V. We will have a few things that need 120V, coffee maker, microwave, and a plug if laptops etc need to be charged. This will be feed by an inverter or generator/plug in.
I decided on 12/3 wire for the 120v, enough for 20 amp circuits, and 12/2 wire for the 12V, this should keep voltage drop to a minimum. I did run a couple of larger circuits as well, one for the fridge and one for the heater and water pump. The 12v is tinned marine wire, the 120v is stranded copper, it was cheaper just to buy an extension cord than I could buy the wire by the foot.
Wiring begun, it was all strung overhead to keep it out of the elements. I am trying to keep as much as possible above the floor.
The wiring went fairly quick but it took miles of wire. I used an entire 300′ roll of the 12V wiring, and had to run a different wire for all the lights. The other main connection area will be in the kitchen cabinets, the switches will be located here, just inside the door.
That is the bulk of the wiring, a few more circuits here and there, but that’s most of it. Next is furring out the walls and cutting the pass through!