Spray in foam now warp drive

[Jmolan]

I need to do a follow up on our insulation. Last Dec. we had spray in done by experienced contractors. They used two kinds of foam as they explained the slower expansion in the tight spots could prevent sheet metal oil canning.
The first few months I was very happy with it, no warpage, no problems. Quiet warm in the winter/cool in the heat etc.
We went to Mexico in March/April and the van skin slowly warped in a number of places. From the heat? It is actually a difficult thing to photograph as the reflection and lighting have to be just so.
It is most notable on the top panel full length, the lower back doors, and some on the lower panel.
I had previously posted how happy I was with great insulation/sound and no warpage. I need to retract that and apologize if anyone has had similar results from my posting. I still really like the insulation, and most times I do not see the oil canning, but it is there, and I will live with it.

 

[Midwestdrifter]

I wonder if its from the thermal expansion coefficient of the foam? I suspect the steel is much lower coefficient, so when the foam expands the metal warps inward, and when it contracts the metal warps outward.

I have 1-1.5" of tigerfoam on my T1N, and no warping even in the summer sun.

Can you share the brand/type and thickness of your foam? Is it 100% coverage? did you have them fill the voids in the pillars and structure tubes?

 

[CJPJ]

It may ~revert~ return to its previous state.

Thanks for the pictures

 

[Jmolan]

This is what came out of the roof fan section. I could find out what kind of foam, I know it is two different kinds.

I have had it between 90 degree and under freezing now, and it looks to be set and not changing.

 

[Jmolan]

I wonder if it from the thermal expansion coefficient of the foam? I suspect the steel is much lower coefficient, so when the foam expands the metal warps inward, and when it contracts the metal warps outward.

I have 1-1.5" of tigerfoam on my T1N, and no warping even in the summer sun.

Can you share the brand/type and thickness of your foam? Is it 100% coverage? did you have them fill the voids in the pillars and structure tubes?

Yes it bumps out at the frames it looks like, and oil cans in between

 

[Midwestdrifter]

Here is a somewhat off the wall idea. Taking a knife and cutting the foam at 2-3 inch intervals in a grid pattern may allow it to flex. This might relieve the stress and prevent the warping? Just a thought. It wouldn't impact insulation value much either way.

 

[glasseye]

That is weird. It looks like it's bowed inwards between the frames. I'd have thought it would bow outwards with the expansion due to heat or the foam curing.

Thanks for the update.

 

[derekhski]

Sorry to see this occur. Thank you for sharing with all of us.

 

[GeorgeRa]

Sorry about your problem. Did they use 2 types of foams on your van or they had 2 options? If they used 2 types in layers each one could have a different coefficients of expansion causing “bimetal” spring effect, bowing inwards. Midwestdrifter idea is a good one or if still possible just replace it with a painless Thinsulate, Hein is in Hood River a few hours drive from Bend.

George.

 

[anoldfireman]

Make sure the two foams are compatable. Some foams will break down others. A lot of contractors just go off of the wholesale brochures of foams untested together.
When our fire engine was done at factory they had it recalled as the foam was reactive to oil and gas we stored in compartment. The foam also offgassed in compartment with circ saw blades which is a no no for some saw blades/diamond mix blades-
Anyway, I remember them saying at factory we toured that the MSDS and other info on foam do not give full picture as some foams are patented/copyrighted and do not disclose ingredients. We were told they would never mix different foams.
Something to look into as if nothing else, get your $ back from contractor-
Anoldfireman

 

[Jmolan]

Sorry about your problem. Did they use 2 types of foams on your van or they had 2 options? If they used 2 types in layers each one could have a different coefficients of expansion causing “bimetal” spring effect, bowing inwards. Midwestdrifter idea is a good one or if still possible just replace it with a painless Thinsulate, Hein is in Hood River a few hours drive from Bend.

George.

They used two kinds, a lesser/slower expanding kind in the tight spots and another on the open areas. It sticks so tenaciously to the sheetmetal I am starting to believe the normal forces that apply to the inside skin being able to stretch or contract is greatly effected, as well as the separation from the frames as far as heating and cooling...who knows?

 

[GeorgeRa]

I am sorry about this problem; it should be a lesson for others that sometime it is better to go with likely better solutions provided by companies exposed to liability like 3M. Thinsulate was developed and extensively tested by professionals to all kinds off conditions. Mixing urethane foams and their catalysts and resins requires extensive testing unlikely provided by a mom and pop shop. I would be worry about polyurethane foam but mixing, ouch.

I don’t know if your sheet metal problem could be reversed, this could be tested on a small section; if it is I would recommend proven solution such as Thinsulate or factory (versus in situ) polyurethane foam sheets.

I put Thinsulate 3 years ago in my van end never look beck, did not have to.

Wishing you best,

George.

 

[220629]

I don't believe that anyone else has ever posted such a result.

After the time that you indicate the cured insulation is likely stable.

Not that anyone asked...

The oil can effect...

Per the thickness picture the foam seems to be well adhered and dense.

The problems seem to be in the small areas between support structure. They didn't occur until you had hot sun beating on the exterior.

The body metal is quite thin. My guess is that your insulation is so good that the heat caused the metal to expand. The supports act as a heat sink keeping those areas cooler. That makes the area of the support structure more stable.

In those small spaces the heated thin metal has nowhere to go. During the resulting stress the adhered insulation acts as a stiffener and encourages the metal to collapse inward.

Another possibility is that the adhered foam stresses against the supports to pull inward against the adhered metal.

Or it is more likely a combination of the above.

Maybe the insulation is too good?

Sorry to hear that your van has the problem. Thanks for sharing the heads up.

vic

 

[GeorgeRa]

Polyurethane foam CTE is an order of magnitude higher than steel as Midwestdrifter pointed earlier. The NASA slides about foam integrity on fuel tanks states clearly that it is not easy and depends on internal foam structure, based on that it is possible that these 2 foam chemistries have different CTEs.
A good conclusion to be drawn from this mishap is to keep the chassis steel sheet metal integrity to itself, any sandwich with strong adhesion can cause a problem. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070008201.pdf


George.

 

[220629]

Not to be argumentative, but if it is strictly the foam deformation why doesn't it happen in other larger areas where the metal would be even more easily stressed/deformed?

...

Or it is more likely a combination of the above.

...
vic

or maybe it has?

vic

 

[Jmolan]

That would be a good point right there. I am not around my van (I am out at sea) but as I recall, the skin had foam connecting the frames where it was previously not connected. I will have to dig up old photos. I have a previous posts shoing the foam job. If the frames stand off from the skin by design,then are connected....by foam really tenatious foam. The new connections would raise stress's where type should not be

 

[ktm805]

I have a friend that owns a major spray insulation company. He says they nock out a ford or chev express van in 2 hours no warp issues. He did a friends sprinter and he was aware of the issue. His crew took over 6 hours to do it, he was as cautious as could possible be and he says his friends van still had some warping, minimal amount but as a professional he wasn't happy with it. He would not do a sprinter again.

 

[GeorgeRa]

I have no doubts that there are multiple factors which could cause sheet metal deformation:

- Difference of CTE between steel and foam
- Difference of CTE within the foam
- Temperature gradient across the foam thickness
- Foam to sheet metal adhesion
- Foam to steel structure adhesion
- And other I missed,

Many theories can be developed which factors were predominant but one factor is valid without a doubt - in situ developed polyurethane foam caused this warp.

George.

 

[220629]

... his friends van still had some warping, minimal amount but as a professional he wasn't happy with it. He would not do a sprinter again.

Did you see, or did he say where the problems presented after his job?


The pictures in post #1 show some definite areas, but maybe it can even be more widespread.


vic

 

[Skydvr]

What was the theory on using the slow expanding foam in the tihter areas?

I would think that in these areas a slower expanding foam would allow you to apply too much foam in an area with not much space to expand leading to deformation and lead to incompletely expanded foam due to limited/lack of oxygen. In the pillars, as the foam at the surface expands and hardens, it would prevent oxygen from getting to the foam deeper in and inhibit full expansion. Similar to what happens if you spray it on too thick. Maybe these pockets of incompletely expanded foam were able to get oxygen as air expanded and contracted with the larger fluctuations in temperature. It's hard to tell from the pictures if the deformation is pushed out metal or collapsed metal. Reflections easily cause optical illusions in photographs.

The foam chemistries could be different leading to a reaction, but you would think that would have happened during the spray process when they were both wet, unless the pillars and channels were still wet and expanded with the heat. The foam chemistries could be the same, but with different proportions of certain chemicals leading to differing expansion rates, which would mean the cause lis elsewhere.