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So I am about to start my first conversion on a used PM 159 high top that I picked up with 20k. I have been doing tons of research but still have a couple questions before I start. Any help is appreciated.

1) I am planning on doing poly insulation for the majority of the vehicle, thinsulate over the ribs and cab, and then reflectix over all of that. Anyone done this method and remember how much thinsualte they required?

2) what seems to be the best way to run wiring, pre insulation, over insulation but under reflectix, or over all of it but behind plywood? Run the wiring down the ribs? And is conduit generally a yes or no? I have seen some conflicting literature? An easier question may be insulate then wire or wire then insulate?

3) Once insulation and wiring is in place do most people just use self tapping screws to screw plywood layer to the ribs? Is there another method that works better? I have seen some people bolt wood strips to the ribs and then screw into that which seems like a waste of valuable space?

Thanks a bunch for any and all help. Super excited to start but want to make sure I do things right the first time.
Chris
 

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Hi Chris- i am 6 months ahead of you with a 159 high roof. There is a lot of info and opinion about insulation- on this site and the sprinter cult as well. I went with just Thinsulate as per the recommendation of Hein in Hood River. Really glad I did- the van is quiet and since I have done things over about three times and added a lot more wiring it has been easier to work around. I insulated/ put in wiring/ insulated some more/did more wiring etc.

I purchased the amount he recommended and it was more than enough. Now that I am putting on paneling, I have been able to double up in some areas.
I use self tapping, but often drill it out first- otherwise the screw migrates and there are places where the metal is double thickness. I am tall so keeping the van height was a big issue. My sheeting is screwed directly to the ribs. Best of luck.
 

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What did you end up doing? I'm at the same stage. How much thinsulate for just ribs, above cabin, and some doors?
I cannot tell you what is correct, only what I did. I put poly-foam anywhere where there are large enough areas to place it. I threaded thinsulate through all ribs and placed larger pieces on/in the rear doors and above cabin. I honestly don't remember how much I ordered from hein but I had to order an additional little bit. Tell him what you want to do and he will give a good estimate. I just under ordered.
 

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If you insulate first with Thinsulate, there are some circumstances where you can embed the wiring into the insulation. If you wire first, it will be virtually impossible to insulate well around the wires, and if you need to get to the wires, you will have to remove the insulation.

If I could start new, my first change would be to run wires along the floor where I know cabinets will be instead of in the walls.
 

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There is NO one best way. If you do everything the same way you aren’t doing it correctly!

I wouldn’t waste 1 second pulling insulation thru anything, personally. But, then again, I’m not a salesman either just an old retired building contractor ;) !
 

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There is NO one best way. If you do everything the same way you aren’t doing it correctly!

I wouldn’t waste 1 second pulling insulation thru anything, personally. But, then again, I’m not a salesman either just an old retired building contractor ;) !
I'm with you. Pulling insulation through a metal channel might provide some (minimal) sound deadening, but that metal rib is going be a great cold bridge.
 

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I insulated then wired. Was no problem for me. I didn't pull insulation through the channels I would run write through. I pulled that after pulling the wires. Running the wiring for electrical was one of the last things I did.

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If running wires was one of the last steps, does that mean your electrical system was one of the last things installed, or did you install base system and then run wiring to each load item as needed?
 

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Looking at the project from near the finish line, I think that would be a superior approach. The downside is that nothing works without wires and we need to use the van as we build to fine tune what we want/need.
 

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Looking at the project from near the finish line, I think that would be a superior approach. The downside is that nothing works without wires and we need to use the van as we build to fine tune what we want/need.
Can you elaborate on why electrics near the end would be better?
 

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If We had seen where the wires needed to go in relation to the cabinetry, we would have chosen much better routes. For example, the channel just below the ceiling appeared in the empty van to be the perfect out-of-the-way place for long runs. In retrospect, it was terrible. Putting the runs there introduced needless complexity and necessitated longer wires, plus there is zero insulation in that very exposed region.
 

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If We had seen where the wires needed to go in relation to the cabinetry, we would have chosen much better routes. For example, the channel just below the ceiling appeared in the empty van to be the perfect out-of-the-way place for long runs. In retrospect, it was terrible. Putting the runs there introduced needless complexity and necessitated longer wires, plus there is zero insulation in that very exposed region.
Thanks. Fair warning, l ask a lot of questions. Part of my job is a business analyst role - understanding how people do their jobs and why they do them as they do. I've learned that it never pays to guess.
 

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If We had seen where the wires needed to go in relation to the cabinetry, we would have chosen much better routes. For example, the channel just below the ceiling appeared in the empty van to be the perfect out-of-the-way place for long runs. In retrospect, it was terrible. Putting the runs there introduced needless complexity and necessitated longer wires, plus there is zero insulation in that very exposed region.
Where would you have taken your long horizontal runs instead? I've been eyeing the channel with the black covers on the floor, but I'm thinking that could be a trap too.
 

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Every one of our long runs could have gone beneath cabinetry and come up through the wall to end points. I didn't realize this until I needed to install the Webasto harness. It was so easy I was stunned.
 

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If running wires was one of the last steps, does that mean your electrical system was one of the last things installed, or did you install base system and then run wiring to each load item as needed?
I did all the electrical at the same time near the end. Check my build thread.

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i'm in the "There's no best way camp" : )

I can say that our Pro-upfitter has chosen over the years to go with wiring harness first as shown in the image below of our PM in his shop... Then he is installing the Thinsulate i purchased from Hein. I'm also in the 'minimalist' camp on insulation since these things are basically rolling metal tents. I just want enough in there to take the bite off the small variation in outside and inside temp. We typically wake up in our rig(s) and it is ~40F or so during the cooler months, no big deal to us over the years of full time RV'ing.



Thom
 

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Thom, love that shot . . . thanks for sharing a great example of 'electrical pre-planning' - - something we did not have the early 'understanding' to do. Fortunately, we did have the clairvoyance to run numerous 120v cables and a 'water pipe' laterally on the floor (in the only spot suitable for such a 'rib-avoiding' lateral run south of the C-pillar) before laying-down the floor - - minimizing the use of the ceiling for that purpose later (we ended up placing a number of our DC cables in the ceiling ribs).
 

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My wiring is run much like this photo. I personally would insulate first so you don't have to move wires to spray glue and install thinsulate. Also you can easily wire around the edges of thinsulate. If I did it again, I'd probably wire after insulating this time instead of near the end because I wouldn't have to take the little bit of extra time to go behind cabinets etc.

My cabinets were built so I could push wires behind. If someone builds without that access, you'd have to pre-wire for sure. If looks like the bulk of the wiring in that pic is coming down to the back so I'm assuming the batteries are there? I put my batteries in front of the driver's wheel well and ran everything down that pillar in the middle of the van.

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