VanDweller Community Forums

Full Version: Insulation Of Hidden Problems In Cargo Trailer
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
So, we brought the cargo trailer home late April.  We should be finished with the insulation and flooring next week.  

I doubt that anyone has gotten as crazy about the insulation project as I have but there are reasons to my madness.  After pulling down all the wall boards I discovered a small amount of rust in a few spots on my new-in-April 2018 trailer!  So I bought some hard wire brushes and cleaned them up and then primered EVERY SPEC OF METAL  in the entire trailer, except the steel frames which are already well coated.  I think this may have something to do with growing up near the beaches and salty air of San Diego.  I learned to paint primer on wood and spray it on metal FYI.

Then I tackled the HOLES.  There aren't a lot of them - but up at the very front corners behind the front wall boards and down where the wires go from the trailer to the trailer brake battery they left a hole large enough for a mouse family to easily get through.  This got plugged with several layers of  aluminum tape and reflectix.  Love that aluminum tape - you can make it fit all kinds of ways.  It's like super heavy-duty aluminum foil but 2" wide on a roll with sticky tape backing that sticks like gorilla glue.  It is also used to seal the insulation boards where the boards have been cut so they can fit into the channels.  The idea is no air gets through and thus the tape (at $8.50 plus a roll).

Another find is that at the bottom of the cargo trailers the outer covering is attached with screws every 10 to 12 inches through frame pieces inside.  Between those screws air can come in at the bottom as although it is flush against the side it is not glued in with lengths between the attachment screws.  So in comes the aluminum tape again - from the inside I close the entire gap around the entire trailer. Why you ask???  When you've been camping as many years as we have you've come upon those places like Lake Tahoe or Salton Sea where mosquitoes spot your lights and find any available slot to slither in. 

We are using R-6 double-sided barrier foam board, 1", so it has the radiant heat barrier on both the side facing out as well as in.  That left the channels between the boards which are about an inch or so wide and just space surrounded on 3 sides by metal, including the piece laying against the outer aluminum cover where the heat and cold will easily transfer.  So I cut Reflectix in strips about 1.5 inches wide, folded them like a taco and inserted them so that the 3 sides of metal had a cover of Reflectix.  There are screws running down these channels so the insulation sticks by piercing it through the exposed screws to hold it up (watch your fingers!).  THEN I cut 1" strips of poly batting - like you would use to make a quilt or blanket - and stuck that inside.  I used little pieces of cut aluminum tape spaced about every 10 inches to keep it from falling out as I added the polyfil from top to bottom inside the channel.  THEN I taped it top to bottom with aluminum tape across the exposed fill, closing the channel completely.

Why??? I watched a Dow Corning insulation video where they used a heat gun to show the loss of heat/increase of cold by weak spots in the insulation.  I'm one of those who believes in global warming or heck, how about those Santa Ana Winds of sourthern California?  Or ever been to Bend Oregon in February?  I'd be wishing I could open my walls and stuff a blanket inside.

Everywhere I could I have taken the time to prime, protect and insulate as best as I possibly can.  As for the build, if that takes 2 years that would be oK and anything I do there just about I can re-do.  But this prep work is a one-time thing that will affect every day's comfort level for as long as we live in it.  When I peeled away the two strips of shiny aluminum running top to bommom  in the front corners I discovered there were large empty air spaces there so it got a few layers of Reflectix.  There is another board that goes in front of that and is the wall facing inside so there will be a 1" piece as well.

For every hot day, for every cold day in our future I sweated (it was hot!) because these trailer walls are much thinner than a house and I figure this is something that will count forever.

I did do video but I'm not even looking, let alone editing, until this baby is done well enough to take off in.
I didn't read in detail, but good on 'ya for setting a good foundation for the framing etc, I haven't heard of a maker doing everything right, I guess too expensive, have to DIY to get quality.

And note that except for window covers, Reflectix really is pretty useless unless facing out into an airgap, and even then is only a radiant barrier, zero insulation.

With limited thickness available, better to fill with Polyiso or another high R-value insulation, and use something stronger to really get a sealed envelope, vapor barrier.
good for you for paying attention to details. highdesertranger
Thanks John & HDS I want to alert cargo trailer folks to areas to look at and fix.

Reflectix does have R value and it varies depending upon where and how it is used. When you buy a roll the diagrams and R values are posted with photos of how it's used to achieve the various values.

I did use it as a radiant barrier in the channel and the poly gave it an air exchange. Then it was sealed with Aluminum tape which gave it another radiant barrier on the opposite side. My guess is I made it into about a R-3 maybe 4. Regardless, it's better than empty metal touching the back of the aluminum wall getting hit with sun all day or same thing if that was -17 below. It all helps.

Also, in the holes and large spaces behind the front wall and corner I used multiple layers to fill the gaps replacing the air with Reflectix layers. So yeah, I am going to guess that is now a 4 at least there instead of a 1.