[ramminjammin]

After sleeping in the pm a few times it really needs insulation from the heat and cold. My concern is with moisture management. In a house you put the vapor barrier on the cold side , in the van it seems the cold side can change .
Wondering if I should leave some ventilation space within the wall or ceiling areas that will be insulated ?

 

[papab]

I'm using thinsulate in the lower half & decided to put an air barrier (house wrap) there. There are drain holes with loose plastic plugs in the lowest part of the wall cavity. In the upper half I'm using polyis foam boards & spray can foam & no vapor or air barrier. There was a thread a while back where we discussed this & there was no consensus.
There's info out there that says that most of the moisture problems in houses aren't due to moisture diffusion, but due to air leaks (warm moist air leaking from inside to outside). I thought about using a vapor barrier, then having removable panels to allow moisture to evaporate when the inside air was dry, but decided against it.
It's a tough problem with a steel outer shell but I think the solution is to make sure that the interior is dry most of the time, or at least half the time. After building up moisture overnight, make sure it gets aired out during the day. Some of the commercial campervan builders use cotton insulation which seems like a bad idea, but it must work out OK or we'd be hearing about it.

 

[jostalli]

This comes up all the time. Popular opinion says do not install a vapor barrier in a vehicle. Do a search on sprinter-source.com.

 

[RDinNHandAZ]

This has been discussed here (at length I believe). Opinions vary. The van is made to have condensation form on its cold interior walls and then travel down to drains along the pinch weld at the bottom. Interiors of doors get lots of water in them as the seal on the roll-down windows is not perfect. All this is fine and rust resistance will allow it to continue for many years especially if the interior drys between condensation events. The problems occur when it cannot drain or is not allowed to air dry. Cotton, spun fiberglass, many rigid foam boards and many other hydrophilic materials keep the moisture from drying and hold it against the walls causing rust..... bad do not use. Other materials may block the drains things like misapplied spray foam, cotton, and shredded or poorly installed paper like labels...... bad do not do.
Hydrophobic spray foam, automotive Thinsulate, Polyisocyanurate foam boards and some other materials do not suffer this problem...... good use them.
Planning for water escape through the normal drains as these materials are installed is possible.

Vapor barrier is not a good idea anywhere in this system. The interior spaces in the walls must be able to dry as air exchange with the wet interior of the camper at night will happen, and air exchange with the dry interior during the day is going to be necessary.

Lastly... Condensation only happens when three things are present: 1. Air with vapor in it 2. A temperature below the dew point for that air and 3. A surface to condense on. If the dew point is INSIDE the dry insulation no condensation will occur...... good. This is why sprayed in foam works, non-moisture absorbing polyisocyanurate works, and hydrophobic Thinsulate works. BTW styrofoam bead board absorbs water like a sponge, blue (or pink) extruded polystyrene absorbs water quite well, fiberglas batts absorb water nicely too. Why go there?

 

[ramminjammin]

Thank you all for responding. I am using a Surface Tablet ,and this interface doesn't seem to ever get me any hits when I do a search. I will heed this information and make sure the drains are free to work. Could use some sort of plastic lattice along the outside wall to give a non absorbing air space. Something like they put under shingles or siding on a house, maybe some heavy nylon net or thin lattice?

Also wondering how to manage the moisture on the ceiling ? Allow air to flow along the metal with a space before insulation? I know they sell Styrofoam vent spacers for when you put fiberglass bats up in the spaces between rafters in a house roof , so use something similar for the van roof. When condensation does drip down it will only land on the Styrofoam spacer and not soak in but lay on top till it evaporates. There will have to be ventilation across the air space to allow drying. Wonder if there is enough room to slope the spacer to allow run off down the side walls and out the bottom weeping holes ?


I did see the condensation all over the interior of my van after sleeping overnight in Maine. The van soon dried its interior out after the sun rose and windows / doors were open. It was quite a remarkable heat conductor when the sun came up it got hot in there pretty quickly.


Appreciate all your help.

 

[papab]

There really isnt a good path for water to go all the way from the roof to the weep holes. The crossmembers are pretty effective dams. I think the best solution is impervious foam glued to the steel, use great stuff to seal up the leaks. Use Foam board or spray it all in. Don't let the moisture get to the cold steel.

 

[RDinNHandAZ]

What he said ^^^^^

 

[KilWerBzz]

House wrap is not a vapor barrier, it breathes. A vapor barrier would be visqueen or similar, a solid that is non-breathable.

 

[jonty]

RDinNHandAZ... your post#4 is worth framing... the most concise and succinct summary of a complex and convoluted topic. Thank you!

 

[RDinNHandAZ]

RDinNHandAZ... your post#4 is worth framing... the most concise and succinct summary of a complex and convoluted topic. Thank you!

Thank you jonty, you may be the only person to have ever told me I was concise and succinct instead of wordy, obtuse and blathering which I normally deserve. Disclaimer: BTW I have since realized fiberglass insulation is hydrophobic so water should leave it if it has a place to drain. It still is a poor choice but not for absorbing water like a sponge.

 

[jonty]

Understood, dont like glass either for this app. I plan to stick to your advice and use Polyiso and/or thinsulate. Your post consolidated my thinking and got me out of the forever pondering stage. Now I can advance to the next pondering planning stages!

 

[jostalli]

Understood, dont like glass either for this app. I plan to stick to your advice and use Polyiso and/or thinsulate. Your post consolidated my thinking and got me out of the forever pondering stage. Now I can advance to the next pondering planning stages!

Insulation and sound deadening is a challenging topic as there seems to be so many options. You must research everything that has been written so you can begin to see what is best. Then you need to crunch the numbers and decide where your money should go. I feel like I have read it all but have still changed my mind several times.




Sent from AutoGuide.com Free App

 

[keithwwalker]

So what makes sense to me is as follows:

Against the inside of exterior body panels:
Best option: Spray foam insulation such that moist air can not reach the cold steel surface and condense water.
Acceptable Option: Peel and stick butyl insulation, may be thick enough to prevent condensation in more temperate areas, but the reverse side is backed with an aluminum foil which won't absorb water
OK Option: is to not have any insulation at all (in areas that don't see harsh winters)

It is imperative to keep any drain channels open and functional.

Against the outside of interior body panels:
I still think that a vapor barrier will prevent moisture from traveling to the outer body panels, and many OEM's do this behind door panels and interior panels. These are usually stuck onto the interior sheet metal with a strip of mastic or butyl.
Inside of the vapor barrier, it seems that some Thinsulate will help with sound insulation a lot, and heat insulation a little. It won't wick moisture either.
Some OEM's also put a fiberglass type of insulation inside of the vapor barrier, but this may be a cost savings over Thinsulate.

For roof liners, a layer of Thinsulate behind an interior panel will probably suffice.
~~~~~~~~~~~~~~
For sound attenuation, one other item should be mentioned. The PM as sold in USA, afaik, doesn't have plastic wheel wells which will reduce road noise to a great extent. The europe FIAT Ducato does. Rhino lining or Line-X may be an acceptable attenuation method.

kw

 

[fogcutter]

so it IS okay to spray foam the ribs?

 

[big wally]

Spray Foam?

Be careful not to put too much foam in the ribs, could cause bulging of the panels.
Also, spray foam, squeaks, when panels move.
I am thinking about stuffing these areas with fibreglass insulation.
I am in the middle of insulating my low 136.
Check YouTube, for some ideas.
Mike from Banff

 

[makevx73]

Be careful not to put too much foam in the ribs, could cause bulging of the panels.
Also, spray foam, squeaks, when panels move.
I am thinking about stuffing these areas with fibreglass insulation.
I am in the middle of insulating my low 136.
Check YouTube, for some ideas.
Mike from Banff

Another idea? Instead of stuffing fiberglass which will work but could cause loose fibers floating around and is nasty stuff to work with - try a couple of bags of 100% polyester fiber fill. It's easy stuff to work with. Not exactly the high-class Thinsulate stuff a lot of folks are buying but it does the job quite well. If you buy the loose fill it stuffs really easy. Just grab some and push it in. I used a paint stir stick and a piece of dowel to push it in with.

I got mine at Walmart but you should be able to pick it up in any stores "craft" department.

Not quite "manly" walking through the rows of fabric and craft things at Walmart, but if you dress decently you won't have to worry about getting your photo added to the growing spread of "Wally-World Hall of Shame" people you see in all those e-mails...

 

[Patrick McCarty 2]

Would it help to spray the interior metal walls of the van with Plastidip? Then adhere Thinsulate over it?

Just trying to figure out how to self insulate without trying to use spray insulation

 

[papab]

I just glued the thinsulate directly to the van wall with 3M super 90

 

[curmudgeon]

Reviving this since it seems like a relevant place to ask. SO, when I first got my van I think I may have made an insulating mistake. I used about a can of great stuff in the very bottom cavity on each side. Was this a REALLY bad idea? Because I noticed a day later is oozed out the lower rear fender in front of the tire. Was this a weep hole I essentially closed up? Should I chip the stuff out? I want to know before I put my walls up.

Jamie

 

[climbing coastie]

Jamie,

Can you post a picture of where the foam is coming out from? Many of us are finding excessive amounts of water in that cavity and to see where your foam is coming from will help us find how water is getting in there.

As far as a mistake, I'm not sure. It could keep water and sand from entering that area OR could help trap moisture next to the metal. Hard to tell.