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-   -   Best Insulation for Walls/Ceiling (https://sprinter-source.com/forum/showthread.php?t=74260)

Midwestdrifter 05-17-2019 01:39 PM

Re: Best Insulation for Walls/Ceiling
 
The distortion of the sheet metal skin is almost entirely driven by the difference in thermal expansion between the foam and the metal. Once you exceed about 1.5 inches of foam these forces are great enough to cause visible warping of large flat metal panels once the temperature varies significantly from the temperature at application. In theory this can also be the case with flat foam sheets although I have never seen this happen in that case.

303Z 05-19-2019 02:57 AM

Re: Best Insulation for Walls/Ceiling
 
Who’s actually had issues with denim? I understand the theory of it holding moisture and potentially getting funky, but have people actually had this happen in their vans? I’m 3.5 years in with denim, just pulled my panels off to do some work, and the denim looks the same as when it was installed. I was half expecting mold or something for how many people talk negatively about denim, and was half ready to replace it with thinsulate. But, it’s current condition doesn’t leave any motivation to scrap the denim and pay for thinsulate. (I read the first 7 pages of this thread, but admittedly didn’t read all pages, so apologies if I happened to skip any info answering my inquiry)

Midwestdrifter 05-19-2019 03:54 AM

Re: Best Insulation for Walls/Ceiling
 
I have had soaked insulation on another van, so it can happen. In dry areas, it's not an issue, but in the humid winter areas, the moisture buildup can happen in a few weeks.

wankel7 05-19-2019 04:58 AM

Re: Best Insulation for Walls/Ceiling
 
Quote:

Originally Posted by Midwestdrifter (Post 769337)
I have had soaked insulation on another van, so it can happen. In dry areas, it's not an issue, but in the humid winter areas, the moisture buildup can happen in a few weeks.

What type of insulation was in place?

What did you do ?

Legwound 05-19-2019 01:15 PM

Re: Best Insulation for Walls/Ceiling
 
Quote:

Originally Posted by Midwestdrifter (Post 768912)
The distortion of the sheet metal skin is almost entirely driven by the difference in thermal expansion between the foam and the metal. Once you exceed about 1.5 inches of foam these forces are great enough to cause visible warping of large flat metal panels once the temperature varies significantly from the temperature at application. In theory this can also be the case with flat foam sheets although I have never seen this happen in that case.

Is this condition as a result of uncured foam at the interface between the foam and sheet metal?

If yes I'm thinking this can be avoided by using a qualified, experienced professional to apply the foam.

Midwestdrifter 05-19-2019 01:49 PM

Re: Best Insulation for Walls/Ceiling
 
Quote:

Originally Posted by Legwound (Post 769397)
Is this condition as a result of uncured foam at the interface between the foam and sheet metal?

If yes I'm thinking this can be avoided by using a qualified, experienced professional to apply the foam.

No. All the foams use for these applications are two part, they will cure regardless of how thick or how much is sprayed on.

It is simply an intrinsic property of the materials. When the material is heated it expands. The metal expands less than the foam does and thus it acts as a bending force on the metal.

gltrimble 05-19-2019 05:10 PM

Best Insulation for Walls/Ceiling
 
I agree the oil canning is likely the result of different material properties. Steel does have a lower expansion coefficient than rigid foam. However, I believe the thin steel is heating up faster than the foam. The steel is exposed to the sun and has a much higher conductivity than foam. In this situation the hot sheet metal is trying to expand much faster than the foam and the bond with the foam is resisting leading to the buckling of the metal.

You can see this same thing happen to many vans without any insulation but to a much lesser degree. More noticeable it seems with darker vans. The thin sheet metal heats up faster than the structure behind it leading to very slight wrinkles. Likely why Mercedes uses a semi-flexible attachment method between the outer sheet metal and the underlying support structure.

I have also seen vans that have a permanent oil canning that appear to be the result of an improper foam install. These vans are warped all the time whereas others are only warped in sunny weather.


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Midwestdrifter 05-21-2019 09:52 PM

Re: Best Insulation for Walls/Ceiling
 
Quote:

Originally Posted by wankel7 (Post 769347)
What type of insulation was in place?

What did you do ?

It was fiberglass. The wet insulation was removed, and closed cell foam sheets were put in its place.

Schneider84 06-01-2019 09:13 PM

Re: Best Insulation for Walls/Ceiling
 
Although not favored by many on this site, I like ultra denim though I live in a dry climate. Easy to work with, high RV, recycled and non-toxic. Ive used the 3/4 foil sound barrier in my roof and maintained 55-60 degrees in van when outside temperatures are as low as 10 degrees

Coast2Coast 06-02-2019 12:45 AM

Re: Best Insulation for Walls/Ceiling
 
I think I will go with a hybrid combo Thinsulate for the ceiling, Foam Board for the large upper wall pieces, Thinsulate or Foam board for lower wall (large areas) and wool for lower wall (tight spots) and rear doors, or maybe just do the lower section in wool, middle foam and upper thinsulate. I need maximum head space on the ceiling, I don't want wool hanging from the ceiling with strings attached:smirk: . All three for the WIN!! :bounce: Toss up between Reflextix or XPS 1/2" for the floor? I wish they made a 3/8" XPS for the floor.


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