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Discussion Starter #1
Hey all,

I am trying to finish up my insulation, and start working on wall/ceiling panels. I am kind of stuck and have a few questions that maybe people with more experience can help answer:

I currently have rigid foam insulation with great stuff in all the gaps and ribs. My foam sits below the level of the structural ribs by about an inch. My plan is to fill that remaining inch with either XPS rigid foam, or thinsulate. Once my insulation is flush with the ribs, I will attach the wall and ceiling panels. I am going to use 1/4" ply for the panels.


  1. Any thoughts on XPS vs thinsulate? I want to maximize r value, which is pushing me towards XPS, but I feel that thinsulate will be easier to work with as it is a little compressible.
  2. How to fasten the ply panels? 3M dual lock looks like it might be a good strong but removable way to go. Or should I just use sheet metal screws into the structural ribs?
  3. If I use XPS and dual lock, will I be able to attach the dual lock directly to the foam? Or will the force of pulling it apart destroy the foam? Perhaps I should only attach the dual lock to the structural ribs? That means I have to be very careful to make the XPS perfectly flush with the ribs...could be difficult.
  4. For wiring that can't be hidden behind furniture (solr panels, roof fan, overhead lights), how can I run the wires? Run them along the ribs? Tape them to the foam?
  5. When anchoring furniture (bench, galley, overhead cabinets), what should I use? Sheet metal screws through the wall panels to the structural ribs? Do I need to do anything before putting up the wall panels to make this easier? Add furring strips? Anything else?


Thanks! I appreciate any advice that might save me some redo work down the road.
 

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Master Overland Custom Vans Tampa
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1. Thinsulate has an R-value if just under 6. But, that is at fully expanded almost 2". If you don't have enough space for it to fully expand then don't use it.
2. I tried 3M Dual Lock to fasten my wall and ceiling panels and lost my excitement over the product when several areas pulled away. I then used self tapping sheet metal screws and they are rock solid.
3. I would not use Dual Lock in this situation.
4. I ran my fan solar and light wires loose behind my ceiling panels. I just made sure they were taped away from where I was putting screws.
5. I used self tapping screws to secure ceiling panels directly to structural ribs. For furniture I glued and screwed furring strips all along the sides of the van then screwed furniture to the furring strips. Overhead cabinets are screwed to ribs and furring strips. I spent several days and many miles off road in Zion and nothing moved or came loose. Some people are nervous about sheet metal screws and prefer nutserts, rivnuts, etc. I agree rivnuts have better holding strength and more secure but once I got into the installation of my cabinetry I thought sheet metal screws into ribs/screws into furring strips were a lot easier to work with.
 

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Discussion Starter #3
Thanks for the detailed response.

1. I would be using the 1" thinsulate. It's R3 or so.

2. That's great to know. I will skip the dual lock (however appealing it is).

3. ok.

4. Do you have issues with the loose wires rattling around making noise while driving? What kind of tape did you use?

5. So you added furring strips outside of the wall paneling? Did you secure the strips to the structural ribs, or just assume that the wall paneling is strong enough to hold the furniture?
 

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Master Overland Custom Vans Tampa
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1. OK. I assumed it was the 5600 that Hein sells. I guess it would depend on price. Thinsulate is the easiest to install.
4. No rattling or noise. I used duct tape and aluminum tape.
5. I cut the furring strips to fit inside each wall void. Used Sikaflex construction sealant to secure to the thin sheet metal side and then pocket screwed each end to the van ribs. Don't use too much adhesive or any solid adhesive to attach anything to the thin sheet metal or you may see it from the outside. Sikaflex is flexible, which is why I used it for all glue and screwed cabinetry.
 

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Discussion Starter #5
Ah, so your furring strips are under your insulation then? Or do you not have any insulation at all?

It's too late for me to do anything like that, all I have left to work with are the structural ribs.
 

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Master Overland Custom Vans Tampa
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Well, my insulation is polyiso foam board with great stuff to fill gaps. To fit furring strips some I glued against the foam board and some I cut gaps in the foam board and stuck the strips in the gaps. You can still use furring strips on the outside of your foam board insulation. Just screw the ends of the furring strips to the van ribs.
 

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Discussion Starter #7 (Edited)
Ah true. May I ask how thick furring strips you used? 1"?

Also, did you install wall paneling over the furring strips then install furniture over the paneling, screwed through the paneling, strips, then ribs? Or do you just not have wall paneling behind your furniture?
 

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BTW I think you should consider the polyisocyanurate instead of XPS as it has a MUCH higher sag (melt) temperature and a higher R value. I seem to remember XPS is rated to about 150 degrees and trust me in the sun on a long hot day the temperature of the skin of the van can get there. We have had people in AZ report 160º plus air temps in their cars.
Just saying. I did like jostalli did and would do the 1" polyisocyanurate and great stuff again. R7+ the radiant barrier=good.
 

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Interesting point on the XPS melting temp. My current layer of isulation is polyiso. I was considering stacking another inch of XPS over it for some better cold weather performance, and also because it seems that XPS is a bit smoother, more uniform and easier to work with. I don't expect the inside of the van to ever reach temps above 120 at the worst, since it is kept in the shade at home, and I always run the fan during the day when in use.
 

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Just because I'm curious, do you have a source for the sag temperature of XPS (or polystyrene generally)? All I can find says that it is a solid at room temperature but begins to flow at 100C, which is well above any temps a van will see.
 

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For everyone, and mikemarmar,
I would suggest you refrence and use GaryBIS's heat loss calculator before you insulate as it helps you decide how much and what to insulate. I found it very useful, used it, and put in a bit less insulation than I had planned as I wanted to get to the sweet spot with my Espar heater so it will run on low at about freezing temps and not need to restart, I got it right thanks to Gary.
http://www.builditsolar.com/References/Calculators/VanHeatLoss/VanHeatLoss.htm
 

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RDinNHandAZ: Yeah that is a great resource. I am hoping to be able to handle temps down to -20F, so I am shooting for R10 on the walls, 6 on the floor, 7 on the ceiling.

MsNomer: Yeah, that report is very concerning. Note two things: It is written by a manufacturer of XPS, and a mean temperature of 15F is actually quite extreme. To get that kind of mean temperature with an indoor temp of 65F, you need an outdoor temp of -35F. Even so...it is one of the reasons I am considering adding a layer of XPS.

To get back to the original topic... Has anyone used attachment methods other than sheet metal screws to fasten wall and ceiling paneling? What methods do people use for furniture? Any other thoughts on XPS vs thinsulate?
 

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Just because I'm curious, do you have a source for the sag temperature of XPS (or polystyrene generally)? All I can find says that it is a solid at room temperature but begins to flow at 100C, which is well above any temps a van will see.
http://msdssearch.dow.com/Published...foam/pdfs/noreg/179-04066.pdf&fromPage=GetDoc

This usage chart has maximum temperature ratings on page 13 and lists 165º not enough against the skin of the van in my opinion which isn't worth much. On the other hand why use it when Polyisocranurate is available, just go in and pick smooth sheets from the stack. XPS also absorbs water and has less R value. The price difference doesn't make sense to me, but hey its your van!
 

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1. Thinsulate has an R-value if just under 6. But, that is at fully expanded almost 2". If you don't have enough space for it to fully expand then don't use it..
Compressing Thinsulate(TM) somewhat won't degrade the performance significantly. SM600L is 1 3/4 thick and SM400L is 1" thick. The SM400L has an R value of 3.8 and SM600L is 5.2. More specs here.

There is no need for all the different layers folks install. Thinsulate(TM) followed by wall panels is plenty for most vans. It doesn't make sense to super insulate the walls and ceiling when there are so many other losses and conductive paths. How many times are you really holed up in a van for more than a night or so? The doors are opened frequently, the vent is open & windows cracked for ventilation, etc. Adequate insulation is important but need not be excessive. The moisture concerns are overblown. It's never a good idea to fully seal a metal enclosure and with vans that can't be done due to all the other gaps and holes that we can't see. Moist air is going to get into all the cavities eventually so the best strategy is to use materials that don't absorb it and to provide some airflow to let those cavities dry out.

We recently installed Thinsulate(TM) in our Ford Transit. And we used it in our Sprinter. In the Transit, we used the scrim side for the headliner since we didn't have time to make a ceiling panel. Then took a 3000 mile trip to Colorado during which we experienced hot and cold conditions neither of which effected our ability to be comfortable in the vans. Link to installation process: http://www.impact3d.com/Thinsulate_installation.html
 

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Interesting point on the XPS melting temp. My current layer of isulation is polyiso. I was considering stacking another inch of XPS over it for some better cold weather performance, and also because it seems that XPS is a bit smoother, more uniform and easier to work with. I don't expect the inside of the van to ever reach temps above 120 at the worst, since it is kept in the shade at home, and I always run the fan during the day when in use.
Thats what I did, 1" of polyiso against the roof and sides, 1" of xps on the inside for the cooler Canadian climate. On a hot day even the xps on the ceiling is warm, however where the ceiling ribs are exposed in the corner the metal is too hot to touch.
 

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To get back to the original topic... Has anyone used attachment methods other than sheet metal screws to fasten wall and ceiling paneling? What methods do people use for furniture?
Mikemarmar, did you ever get info on how to install wall panels and furniture? What did you end up doing? I'm doing wiring now and am about to make/install wall panels.
 
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