Forum Discussion

Jfet's avatar
Jfet
Explorer
May 21, 2013

talking insulation: spray-in polyu vs polyisocyanurate sheet

Putting this on a separate thread to my camper build because it may be of interest to those with existing campers they are restoring.

I was almost sold on spray-in polyurethane foam, done by a contractor, but I had worries about the fire hazard and the very toxic fumes that would kill you before the fire even got a fair chance. I do not know if these are overblown fears but I only have one life to beta test it. In homes they require a sheetrock type material as a thermal barrier...that isn't going to fly for our camper build.

In researching this more, I came across a long thread on an airstream forum about the downsides of spray-in foam. Two that popped out at me were 1)repair issues if you need to remove a sprayed panel, and 2) the foam turning into powder in non-stationary applications other than residential homes. I haven't finished the thread yet, but it gave me the idea of looking into polyisocyanurate sheets as an alternative.

The thread is here: http://www.airforums.com/forums/f46/spray-foam-insulation-46536.html


In looking for a polyisocyanurate sheet, I found DOW makes them with a aluminum facing and fiberglass reinforcement in a R6.5 rating for 1 inch thick. They are fire rated to not combust without an external source and can even be used in living areas without any thermal barrier at all.

DOW Thermax sheeting: http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_08c3/0901b803808c3035.pdf?filepath=styrofoam/pdfs/noreg/179-07942.pdf&fromPage=GetDoc


What do you guys think? Any opinion?
Truck Campers

9 Replies

  • recycler's avatar
    recycler
    Explorer
    May 23, 2013
    Jfet wrote:
    recycler wrote:
    I have read they make a poly spray foam that is fire retardant for use in enclosed areas were it would be difficult for someone to get out..the polyiso is some good stuff to use is what will be going around my refer unit do to it's fire rating..the only problem i see in using sheet foam is getting a tight seal..i had to use can foam on my bead board to tighten it up...my two cents..


    I have not been able to find a poly spray formula that says it is fire retardent but I would certainly be interested in it. I have read that Bigfoot uses sheet foam in some campers but maybe used spray foam in the past. Bigfoot and S&S are two manufacturers I wouldn't mind copying.


    with your unit sheet foam may work alright..i figure it has the studs more evenly space than mine.. the down side of building a camper that big in the space of one car garage using junk tools.. :B plus the round edges of the steel should make it easier to stuff into cavity and i will keep an eye out for the article about the foam
  • Jfet's avatar
    Jfet
    Explorer
    May 22, 2013
    recycler wrote:
    I have read they make a poly spray foam that is fire retardant for use in enclosed areas were it would be difficult for someone to get out..the polyiso is some good stuff to use is what will be going around my refer unit do to it's fire rating..the only problem i see in using sheet foam is getting a tight seal..i had to use can foam on my bead board to tighten it up...my two cents..


    I have not been able to find a poly spray formula that says it is fire retardent but I would certainly be interested in it. I have read that Bigfoot uses sheet foam in some campers but maybe used spray foam in the past. Bigfoot and S&S are two manufacturers I wouldn't mind copying.
  • recycler's avatar
    recycler
    Explorer
    May 22, 2013
    I have read they make a poly spray foam that is fire retardant for use in enclosed areas were it would be difficult for someone to get out..the polyiso is some good stuff to use is what will be going around my refer unit do to it's fire rating..the only problem i see in using sheet foam is getting a tight seal..i had to use can foam on my bead board to tighten it up...my two cents..
  • jtlingo123's avatar
    jtlingo123
    Explorer
    May 21, 2013
    I am finishing up fixing the cab over area in my TC right now and I took out the front window due to excess moisture and I bought the white foam board that has the aluminum side to it and it is rated for fire, mold resistant, and an R rating to it. It's not as good as the pink foam but good enough for me!

    Josh
  • Jfet's avatar
    Jfet
    Explorer
    May 21, 2013
    69 Avion wrote:
    I wonder how Avion was so successful with the spray in foam all those years.


    I have no clue...did Avion use polyurethane spray in foam? Did they use a thermal/fire barrier on the interior between the foam and the inside?


    I do see that S&S Campers uses Thermax....that could be a vote for that route as I have heard they are a quality builder.

    http://www.s-scampers.com/ponderosa.php

    I could still be convinced of the spray in, as it would be easier. I would want the answers of fire saftey first though.
  • 69_Avion's avatar
    69_Avion
    Explorer
    May 21, 2013
    I wonder how Avion was so successful with the spray in foam all those years.
  • Jfet's avatar
    Jfet
    Explorer
    May 21, 2013
    thundercloud wrote:
    Look into Icynene foam spray. It does not off gas nasty chemicals and is fire resistant. Here is a link Icynene


    hmmm from that website you linked:

    "Do I Need a Thermal Barrier?

    In an occupied space, you need a thermal barrier adjacent to either low density or medium density foam - this could be ½ inch gypsum board, or a code-prescribed barrier per R316.4, depending on the spray foam section of your local code. See each Icynene spray foam product to check which paint-on or spray-on thermal barriers can be used.

    If the space is unoccupied, you don't need a thermal barrier.
    "
  • donn0128's avatar
    donn0128
    Explorer II
    May 21, 2013
    Do so e more research. I remember seeing a few years ago a story about a non toxic spray foam insulation. Might be hard to find, but definitely worth the effort. Also i have seen DIY kits for reasonable price.

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