Insulation 165°F Maximum Service Temperature

[featherliteCT1]

I want to insulate the ceiling of my 16 x 7 x 6.5 aluminum cargo trailer. However, I am concerned about the maximum service temperature rating of foam insulation.

My research discloses that (i) Polyioscyanurate (Polyiso), (ii) Expanded Polystyrene (EPS), and (iii) Extruded Polystyrene (XPS); rigid foam boards have a maximum service temperature of 300°F , 165°F and 165°F, respectively.

I do not want to use any foam board type except the XPS (based upon all the pros and cons you guys have already explained elsewhere).

For example, the published specifications for the Owens Corning Pink Panther XPS Rigid Foam Insulation expressly states that the foam board must not be used in a roof application and that this product “is a thermoplastic material with a maximum service temperature of 165°F.”

Question: How hot do you think the roof of an unpainted, bare aluminum trailer would get setting out in direct sunlight, all day, in a geographic location like Florida or Texas? Keeping in mind that the insulation would make the roof skin retain more heat that otherwise would get dissipated into the trailer if there were no insulation.

In any event, my understanding from reading some physics materials on thermodynamics of sunlight is that the temperature could never exceed 190°F.

I am in southern Indiana and have no way of performing any actual testing with my infrared thermometer at this time, because the intensity of our sunlight is poor this time of year.

FYI, Pink Panther does make a higher temperature rated foam board but it must be special ordered. Right now, I do not know the temperature rating of that product, the cost per sheet, nor exactly what I want. Consequently, I have not pursued that as a possible alternative route.

Thank you for your help!

Ron

[Iconfabul8]

I have to admit I didn't put any thought into the thermodynamics of my roof. Maybe I should have, but hey it's too late now.

I guess time will tell for myself and many many more around here that just went for it. However, I would like to hear from anyone who has had foam board in a roof for an extended time period and then removed and examined it.

[QueticoBill]

What is the consequence of exceeding the maximum service temperature?

[featherliteCT1]

My initial guess would be that excessive temperature might cause: (i) continuous gassing over time (my greatest concern) and/or (ii) a reduction of R value.

I suppose crumbling might also occur, although I am less concerned about that aspect. Again, I am just guessing.

Thanks for the feedback!

[QueticoBill]

Found this. Still not sure what the consequence is but it softens. And is a little soft at 170 fatal? Time to call Dow.

"What is the maximum use temperature of ETHAFOAM™ brand products?

Foams such as ETHAFOAM brand polyethylene foam tend to soften at higher temperatures, as this is a characteristic of the thermoplastic resins from which they are produced. As temperature is raised, the foam may therefore become too soft for some applications.

Unfortunately, there is no consistent industry definition of "maximum use temperature." One standard laboratory test commonly performed on polyethylene foams subjects the foam samples to 24 hours in an oven at 70°C (158°F). The samples are then returned to room temperature and measured for linear dimensional change in all three directions. Under this test, ETHAFOAM products consistently show less than 1% linear change. Results from this test are sometimes used to determine a "maximum use temperature." Note that this test is carried out with no loading placed upon the foam. If the foam is expected to maintain its function and dimensions under a load it may be necessary to reduce the maximum use temperature accordingly. Specific testing under anticipated loads and use conditions is recommended when loads are to be applied at temperatures above around 49°C (120°F)."

[McDave]

Paint that roof with Henry 587, 1st order of business. Get it done. Dollar for dollar the best upgrade so far. About $50.00, and a half a day of prep/paint. Makes a huge difference.
Then use the same PolyIso you used everywhere else, fir out and double up if you wish.

McDave

[QueticoBill]

Seems difficult to get polyios to bond to the skins like XPS or even EPS does to take structural advantage of the stressed skin construction. Can you get polyiso without a facing? I just have found the facing - usually foil - to peel very easily, which suggests to me they would fail from the shear between skin and foam.

[featherliteCT1]

Paint that roof with Henry 587, 1st order of business. Get it done. Dollar for dollar the best upgrade so far. About $50.00, and a half a day of prep/paint. Makes a huge difference.
Then use the same PolyIso you used everywhere else, fir out and double up if you wish.

McDave

Yes, thank you McDave,

In any case, I think painting the roof as you suggest is a must. However, I am still wanting to know if the roof skin will exceed 165 degrees F. I suspect it will.

I am also guessing that the paint will only reduce the temperature of the exterior roof skin about 20 degrees in the hottest scenario.

Here is a link to a positive review where a Liquid Ceramic Insulated Coating was applied to an aluminum horse trailer roof with what appears to be good testing data to measure the heat reduction. However, the test was performed in May, in Colorado, when the sun was not very intense. The maximum exterior temperature recorded without the coating was only was 120 degree F, with a 19 degree F reduction with the paint. I suspect the reduction would not be proportional at higher temperatures.
https://mrtrailer.com/ceramic.htm

[GuitarPhotog]

I don't have a CT, but the skin of my brown all-aluminum teardrop trailer was measured (with an IR thermometer) at 140F one sunny day with outside temps ~100F.

Just one data point.

My rigid foam (dunno which type) insulation is glued directly to the inside of the skin with 3M Fastbond 30NF contact cement. It was recommended for bonding foam to metal with high-temperature service. I have seen no (zero) melting or deformation and little crumbling around the edges.

My $0.02 worth.

<Chas>

[McDave]

Seems difficult to get polyios to bond to the skins like XPS or even EPS does to take structural advantage of the stressed skin construction. Can you get polyiso without a facing? I just have found the facing - usually foil - to peel very easily, which suggests to me they would fail from the shear between skin and foam.

The best way to install the foil faced PolyIso is leave a 1/4" air gap between the inside of the trailer skin and outward face of insulation. That should reduce the thermal transfer and increase overall R-value.

McDave

[QueticoBill]

Seems difficult to get polyios to bond to the skins like XPS or even EPS does to take structural advantage of the stressed skin construction. Can you get polyiso without a facing? I just have found the facing - usually foil - to peel very easily, which suggests to me they would fail from the shear between skin and foam.

The best way to install the foil faced PolyIso is leave a 1/4" air gap between the inside of the trailer skin and outward face of insulation. That should reduce the thermal transfer and increase overall R-value.

McDave

But do you agree that would make it of no structural value? That seems the great feature of ply-foam-ply, that they act together and can span without other support.

[aggie79]

Seems difficult to get polyios to bond to the skins like XPS or even EPS does to take structural advantage of the stressed skin construction. Can you get polyiso without a facing? I just have found the facing - usually foil - to peel very easily, which suggests to me they would fail from the shear between skin and foam.

The best way to install the foil faced PolyIso is leave a 1/4" air gap between the inside of the trailer skin and outward face of insulation. That should reduce the thermal transfer and increase overall R-value.

McDave

But do you agree that would make it of no structural value? That seems the great feature of ply-foam-ply, that they act together and can span without other support.

I don't think you need to worry about structural value in a cargo trailer. They seem to do just fine structurally without insulation.

[QueticoBill]

Missed it was a cargo conversion. Sorry.

[wtcreaux]

Paint that roof with Henry 587, 1st order of business. Get it done. Dollar for dollar the best upgrade so far. About $50.00, and a half a day of prep/paint. Makes a huge difference.
Then use the same PolyIso you used everywhere else, fir out and double up if you wish.

McDave

In any case, I think painting the roof as you suggest is a must. However, I am still wanting to know if the roof skin will exceed 165 degrees F. I suspect it will.

I am also guessing that the paint will only reduce the temperature of the exterior roof skin about 20 degrees in the hottest scenario.

In N TX where summer sun made the aluminum roof so hot I couldn't put my hand on it. I painted with Henry's on a cool day, several coats. Now, in the midst of summer, I can place my hands on the roof, I can also sit on while working. Interestingly enough, even with 110F outside, the Henry paint still feels cool to the touch. Dollar for dollar, painting the roof with Henry is the most cost-effective action.........

[featherliteCT1]

Thanks for the feedback. I think I will paint the trailer roof with Henry’s paint the first thing I do, before I start insulating the interior. I think it will make it cooler inside the trailer as I work. The trailer will be sitting outside in the sun as I work … at least until I get a carport.