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Foam insulation an enclosed trailer

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I was considering insulating my enclosed trailer and am wondering if anyone had experience doing this.  Steel framed trailer with screw-less (bonded) aluminum side panels and wood interior panels.  My thought was to remove the interior wood sides and take it to a company that sprays urethane foam, then re-install the panels. Besides allowing the trailer to be heated in the winter, I'm sure it would add some rigidity and dent resistance to the thin aluminum side panels.  My concern is if it will negatively affect something I have not considered.  I know the sides like to wrinkle in the hot sun when the aluminum expands.  Will having foam insulation adhered to them cause issues?  I'm sure some trailers are sold this way but maybe they just use the loose Styrofoam panels.


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With the cost of sprayed foam being what it is and the amount of labor involved,  I might agree that it may not be very economically feasible but if the man has the money I don't see why it would be a total waste of his money. Spray foam is sprayed directly to the interior of metal walls of pole barns and other structures all the time, so I can't see what might be a problem spraying it to the inner metal wall of a trailer then placing the wood panels back?

And like Mike, I'd be interested in hearing why a car should not be stored in an enclosed trailer.  The only concern might be that of condensate if a wet car is brought in but that stands to be the case with any tightly enclosed trailer.

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I better get my "stored" car out-a-da trailer...................

And into the garage, where the sage brush blows in every time I get my "driver" out to go to work.

That sounds like a great plan.............NOT !!!!


Now back to business.


Regarding you insulating your trailer, a great idea.

I don't think you need to pull the interior walls, unless you want to cut blue foam panels and fit them between the uprights and secure them with PL3000 construction glue.

BUT you could do what they do to old houses.

Drill a hole at the top and bottom of each "bay" and shoot expanding foam in the bottom hole, till it comes out the top.

There are companies out there that retrofit old houses this way, and for them, this would be a half day's work. Especially if you drill the holes, per their instructions of course.


Mike in Colorado

PS; Pic's of mine with the escape door I made.



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An enclosed trailer does not have " wall depth " thick enough to benefit from spray in foam insulation.

The exterior aluminum skin is thin & will deform easily.

You cannot take home insulation methods & apply them to an enclosed trailer wall because an enclosed trailer wall is not an exterior residental home wall.

If the OP wants to remove the interior wood panels - install rigid foam insulation - then re-install the wood sheeting ...

Fine - but a waste of time & money.

An enclosed trailer is designed for moving cars - not storing them in a climate controlled environment.

You cannot economically control temperature & humidity in an enclosed car hauling trailer - they are not engineered for that purpose.




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  • 2 weeks later...
  • 1 month later...

Take a trip to Lowes or Home Depot to see if they stock sheet foam or rolls of flex foam.  Some actually comes with peel and stick glue that would work nicely inside the thinner trailer walls. 


Although car trailers may not be designed to be temperature controlled, there are lots of old RVs with minimal fiberglass insulation that is not nearly as effective as foam.  A little insulation can help minimize heating costs if all you need to do is keep it above the dew point to prevent condensation and/or freezing.  Car trailers are also very effective in keeping rodents out.

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 I had a travel trailer that was fully insulated with fiberglass insulation.

 (according to the advertizing yea!  Actually it had 1/16" insulation)


 I removed the ceiling and installed 2" foam between the roof bows.

 It made a total difference.

 Just walking thru during the hot sun of the day, you could feel the radiant heat difference in the space that I could not do and the foamed area.


 Doing your trailer will keep the temp changes less between night and day. I would do the rigid foam board v/s the spray.

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  • 2 weeks later...

The county limits the number and size of out-buildings I can have on my 2 acres. BUT they don't tell me how many registered enclosed car trailers I can have. I have FOUR enclosed car trailers now.. All have cars and some restoration parts for some of the projects in them. ALL cars are looking just fine. AND ready to go when I want to drag a trailer to an event. My workshop has plenty of temperature change every day, Each time I roll up a door, in comes the current weather.. Not So with the enclosed trailers.

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When I took about a third of the 1/4" plywood off the interior of my new 24' car hauler to build my "escape" door, I should have kept going and taken it all out.

Since the side wall studs are 1" x 1.5" steel tubing, just like the top, it would have been a great opportunity to insulate the whole thing with 1" blue foam.


I suppose it is still not too late to tackle this as a spring job. Can't do it now, as the Baby is all tucked in there for the winter 


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