Question about insulation.

[RandyH]

I'm considering a cargo trailer conversion and I've noticed everyone uses rigid foam insulation for the walls and ceiling. What are the reasons for not using regular fiberglass batt insulation? Seems like if you overlaid the metal wall members with 3/4", that would give 1-3/4" walls. The batts are 3-1/2"; they can be easily compressed to fit between the studs. I know the R value of the insulation would go way down, but still above what foam insulation would give.

Most all "regular" campers use fiberglass batts so why not?

Thanks,
RandyH

[jwhite]

I think most will agree that with the traveling overtime it will settle at the bottom?
I used 2 layers of board and it fits flush with the studs if you take your time the foam can be fit really snug so there are no gaps also I took duct tape and sealed every crack/space and then it's really air tight.

[MtnDon]

R13 fiberglasscompressed to 1.5" becomes R6.6.
1.5" of blue/pink XPS foam = R7.5

Some mfg of RVs use batts because they are cheap. Both the mfg and the batts.

[hankaye]

RandyH, Howdy;

First off ... WELCOME !!!

Having owned an 'older' Travel Trailer with the batt style insulation I know that, in mine,
The batts were applied in sections and there was a 2"X2" (wall thickness), was installed
about every foot and a half (1.5'), along the vertical to support each piece. some sections
were longer and some shorter so that they could be staggered. My 'newer' (2008), RV (Home),
has the filon walls bonded to a foam core for the sides. The rear wall and front nose cap
are filon exterior wall with the fiberglass batts, again with the staggered braces.

hank

[walkrdg]

About thirty years ago (geez!)... I had a Ford van I wanted to insulate and panel. In a used book store, I found a book by someone who had done just that. He suggested using pink fiberglass insulation, but the clever thing he said to do, was to first paint do-it-yourself undercoat on the metal and stick the fiberglass into it. This would help hold the fiberglass to the walls. The paneling, then, compressed the whole works tighter. He said the process would help keep the vibration from working the glass to the bottom for a long time. Well, that all made sense to me, so I insulated my van that way. What began sounding like marbles in a tin can, wound up like driving a Cadillac!

How long did it last? I don't know. Several years later, I traded in the van on a new Tacoma for work.

And, would I do it that way again? Nope. I'll be using rigid foam in the trailer, when I get to it. Much simpler process to install, will make the walls much more solid, and will definitely increase longevity.

Good Luck,
Dave

[RandyH]

OK, got it. I hadn't considered the settling factor. I'm sure I'll have many more questions.

[OverTheTopCargoTrailer]

It's always funny how a thousand guys do it one way & along comes somebody who does anotherway.

I guess fiberglass & lithium batteries are two good examples.

Cheers ottct.

[bobhenry]

I pulled out hands full of snotty wet fiberglass and when it came time to re-insulate the tiny house on wheels I used blue foam. It is hydrophobic and will not support mold as well as adding a bit of shear value to the wall if fit in tightly. Where you want wires or plumbing just carve out as needed.



Notice how the moisture has rotted the plywood below.

foam in the floor


foam in the walls

I was lucky in that the wall panel plant where I work throws out bales and bales of window and door cut out sections of blue foam. I was able to stack and stack until the 2x6 wall cavities were full , making an R-21 +/- in the walls.