Do the Ceiling forget the Walls? Vapor Barrier?

[cynanne]

I am considering a compact cargo van (nissan nv200) and feel that moisture/condensation will be a big issue. I will often be in cold climates so not insulating at all is not an option. I would put at least one vent in the roof. Does anyone have advice/experience on insulating only the roof and ignoring the floor and walls? I would put something like a small mat on the floor and maybe seal the corners of the walls and roof somehow. Also does anyone know about the use of a vapor barrier and what type of insulation is best if one is concerned about moisture damage? Any info/experience is appreciated.

 

[Trebor English]

If only the roof is insulated the maximum summer heat will be reduced.  In the cold it will be cold like outside with no wind.

 

[Trebor English]

The vapor barrier separates the moist inside from the dry outside.  If the moisture barrier is cold there will be condensation.  The steel skin of the van is the final moisture barrier.  You can put up plastic sheets or other stuff but you can't keep humidity inside and keep it away from the steel skin.  If you insulate the outside and heat the steel skin that will stop the condensation.  Insulating inside and having the skin cold will cause condensation.  All you can actually do is reduce the moisture in the air.  A heater that puts water in the air like a Mr Heater Little Buddy will make the steel skin and the windows run with water or be coated with ice.  If you put up paneling you can cover it so you don't see it.  

Outside vented heater and an exhaust fan are the only really good solutions for a cold climate.  Wood stoves and diesel heaters are vented outside because the fumes are bad.  Propane can go either way.  

I make it a point to avoid cold places.  I still have had ice on the inside of the windshield.

 

[maki2]

You absolutely do need some type of insulation on the roof. That is to keep the condensation from forming on the metal surface and prevent it from dripping down on you. Condensation will also form on the walls but it will run down the walls and accumulate at the base of the wall rather than raining down on your head.

So for your personal comfort the ceiling comes first if time and budget are severely restricted. If you have no big interior scheme decided at this point then you can do something very simple to stop the condensation issue. EVA foam is a soft, closed cell foam insulating material that can be adhered to the metal with Weldwood Original Formula Contact cement. It comes in cans of various sizes at the hardware store, it is yellow colored and does have VOCs in it. Brush it on the clean metal surface and also put a coat onto the surface of the foam. Wait the recommended amount of time before placing the foam into position on the metal. Then it will instantly grab. This type of contact cement is rated for the high temperature that can develop on the interior of the metal vehicle roofs. In fact it has been the standard adhesive used for that purpose for more than 60 years. You do want the original formula with VOCs in it as that is the one is better for overhead work. The water based versions don't initially grab strongly enough to be reliable for overhead work.

So where can you find some EVA foam that looks attractive and is easy to work with? That material is available in hardware stores and home goods stores such as Home Depot and Lowes. It is the soft, cushioned foam drawer liner that comes in rolls. It has a washable surface and it won't off gas and it won't deteriorate and fall apart on you. You can cut it to size with scissors. It has some sound deadening properties as well as insulating properties. Obviously as it is not all that thick it is not a substitute for the R value you would get from a 4 inch, insulated wall cavity. But it will solve your condensation issue. White is a good color for its light reflecting abillity to brigthen the interior but it does come in other colors such as beige, grey, black. This is just one brand of it, I chose the link because it comes as a long roll. But there are other sizes being sold. https://www.lowes.com/pd/Duck-12-in-x-30-ft-White-Shelf-Liner/4634607

I myself used a variation for my ceiling, it too is EVA foam but thicker and more expensive. Of course since it is thicker it provides more insulation and sound proofing. That product comes from the automotive industry and was used originally for creating the soft underlayment that went under the exterior vinyl roof coverings on cars such as Cadilacs and other town cars. It is known as Landau foam. But it does not has as strong and washable of a surface which was not an issue for my installation as I was using a head liner material for the finished surface that was applied over it. I did apply it with the Weldwood Original Formula Contact Cement.

 

[jonyjoe303]

I never encounter any moisture problems and I run a swampcooler almost every day, but even that doesnt produce any moisture on my walls and ceiling. 

When I ran a mr heater is the only time I encounter any moisture, but only notice it on the actual propane canister and on my front windshield. Never on any of my walls or ceiling.

You need to install insulation everywhere if you want good results. I got every inch of the back of my van covered in insulation. I got very good results this winter. I get over a 15 degree difference between inside/outside and havent use the mr.heater so far, and now summer almost here. Don't forget the floor, lots of cold gets inside from there. I never got any mold etc on my rtech insulation and I have had it installed almost 6 years, and never used any vapor barriers, I just hotglue the rtech foam directly to the metal skin.

If you have any carpet on your floor remove it, if that ever gets wet, it won't dry. I encounter that for a while where I was smelling mildew and couldnt find the source. It was a small section of carpet I had never removed that was wet. Now the floor is all rtech insulation. 

rtech foam insulation


winter readings at 5 am different days, no heater

 

[flying kurbmaster]

JJ those are excelllent results with no heat. I agree best to insulate the whole van especially if you are in cold or hot places if you want to be comfortable and enjoy your van. I insulated it once then I added more to the ceiling inside cupboards and the floor, I have vented propane heater and an insulated bulkhead with an insulated door to get to the cab. I haven’t been in extreme cold but low 20’s and I am toasty warm all day long with heater on low. Sometimes even having heat on damp days is nice to dry thing off, and feel comfortable.

 

[Dingfelder]

I think some of this depends on how self-indulgent you are. I usually keep windows open at night even in freezing weather, but all it takes is keeping the windows closed more often and/or using the heater more often (not even a lot more often) to have my windows swimming in water and sometimes dripping down onto my walls. Open the windows long enough and it clears right up.

So perhaps one of your best solutions might be thinking in another direction, like ... get a really good sleeping bag(s)/blankets, maybe a hot water bottle or two, and keep all your heat local instead of dispersed, while opening your windows as much as you can stand it. Doubling up on your clothing layers helps a ton too.

This can be very hard if you haven't trained yourself over the course of weeks to acclimate to the cold. But even if you can't do it now, it's something to think about for the future, and start working toward (by acclimating yourself) as soon as possible.

 

[cynanne]

Thank you all. I wish  Bob would do a video or two on this.

 

[Gr8ful]

60% of heat goes out the ceiling, 40% out the walls & 20% out the floors but as everyone has said insulate everything. Use Thermax foil coated sheets as least 1" which will only be R-7 but Thermax is fire resistant so you won't die of toxic fumes before you even see a fire. Construction adhesive & metal cap (round 2" thin steel plates) with sheet metal self tapping screws to hold the sheets on. If there are ribs your attaching too & a hollow behind you can fill that void with latex non expanding foam that doesn't burn & can buy in small cans or a large contractor tank. Insulation done right will save on heat & add to comfort.

 

[lenny flank]

The best solution for condensation is air flow and ventilation. Crack the windows, or run the vent fan.

I've never seen anything to convince me that "vapor barriers" do anything useful.

 

[Gr8ful]

In a stick house they block the wind & let water vaper pass thru but a van is steel or alum so they won't do anything.