Spray in foam now warp drive

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Robert-NE

Member
I reviewed this thread with one of the home builders that I work with, and he confirmed that every spray foam contractor he has ever worked with has insisted that spray foam does not shrink. If it did, it would open up gaps along the framing structure and defeat the vapor-barrier property of the foam. We have also seen spray foam in attics and other spaces that were installed years prior, with no evidence of shrinking.

We are thinking that the structural members of this van were not insulated with spray foam (maybe not at all?), which may have caused a temperature differential in the sheet metal skin. This theory is highly possible since spray foam in narrow spaces such as the framing members has a good probability for over-expansion and bulging of the vehicle skin, and therefore might have been avoided altogether by the spray foam contractor. While not knowing for certain without seeing the inside of the van walls, the condensation pattern on the exterior of the van in the first photo would suggest that the skin along the framing members is warmer than the open areas.
 
gltrimble

gltrimble

2017 170 4x4
Robert-NE said:
I reviewed this thread with one of the home builders that I work with, and he confirmed that every spray foam contractor he has ever worked with has insisted that spray foam does not shrink. If it did, it would open up gaps along the framing structure and defeat the vapor-barrier property of the foam. We have also seen spray foam in attics and other spaces that were installed years prior, with no evidence of shrinking.

We are thinking that the structural members of this van were not insulated with spray foam (maybe not at all?), which may have caused a temperature differential in the sheet metal skin. This theory is highly possible since spray foam in narrow spaces such as the framing members has a good probability for over-expansion and bulging of the vehicle skin, and therefore might have been avoided altogether by the spray foam contractor. While not knowing for certain without seeing the inside of the van walls, the condensation pattern on the exterior of the van in the first photo would suggest that the skin along the framing members is warmer than the open areas.
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The warping of the sheet metal is not necessarily caused by the foam shrinking or expanding upon installation. When you attach or glue two fairly rigid components together, sheet metal and rigid foam, with two different expansion coefficients, then there is the potential for one of them to deform when exposed to extreme temperature differentials.


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R

Robert-NE

Member
gltrimble said:
The warping of the sheet metal is not necessarily caused by the foam shrinking or expanding upon installation. When you attach or glue two fairly rigid components together, sheet metal and rigid foam, with two different expansion coefficients, then there is the potential fo one of them to deform when exposed to extreme temperature differentials.
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I will agree to that. However, this seems to be a one-off situation, and I know there are a number of vans out there that have spray foam installed. Therefore, more information is needed to figure out if this is really a universal spray-foam concern or, more likely, a one-time installation issue.
 
Zundfolge

Zundfolge

Always learning...
Very valid points, all of which lead me again to my initial question: Could a decoupling membrane - such as reflectix - mitigate this situation?
 
R

Robert-NE

Member
Having gone back to read other threads about vapor barriers, it would seem that having two barriers (metal skin as one and closed-cell foam as second) with a gap in between is inviting a moisture trap. Still trying to wrap my battered brain cells around all of this, but you might be trading one issue for another.
 
R

royce

Member
Zundfolge said:
Very valid points, all of which lead me again to my initial question: Could a decoupling membrane - such as reflectix - mitigate this situation?
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I used 3/4" armaflex as the first layer against the van skin, then spray foam.
The van still warped, some, not bad at all, so far.
There is a lot of places where I could not get the armaflex into and just filled with spray foam.
Looking at how the inner frame and the skin are bonded with a flexible adhesive, that allow the inner and outer skin to move some what independent of each other, I agree with the theory that tying the inner frame to the outer skin with spray foam is a a major factor.

I foamed mine knowing that it was more likely going to warp, than not and could live with that.

I hope this helps with your question
 
Zundfolge

Zundfolge

Always learning...
royce said:
I used 3/4" armaflex as the first layer against the van skin, then spray foam.
The van still warped, some, not bad at all, so far.
There is a lot of places where I could not get the armaflex into and just filled with spray foam.
Looking at how the inner frame and the skin are bonded with a flexible adhesive, that allow the inner and outer skin to move some what independent of each other, I agree with the theory that tying the inner frame to the outer skin with spray foam is a a major factor.

I foamed mine knowing that it was more likely going to warp, than not and could live with that.

I hope this helps with your question
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Is your van a dark color?

I think I will do half and half and just see what happens, it is my van after all :) It's again, also white so I'm not as worried about warping.

Another point to consider: I think that all of the anecdotal evidence of *potential spray foam induced* warping I've seen so far has been with relatively new and dark vans. I'm going to hypothesize here that the newer dark vans have had less time exposed to the elements, heating/cooling cycles etc, and that perhaps foaming them early on in their lives inhibits them in some way, "breaking in" or some such thing...
 
R

royce

Member
Zundfolge said:
Is your van a dark color?

I think I will do half and half and just see what happens, it is my van after all :) It's again, also white so I'm not as worried about warping.

Another point to consider: I think that all of the anecdotal evidence of *potential spray foam induced* warping I've seen so far has been with relatively new and dark vans. I'm going to hypothesize here that the newer dark vans have had less time exposed to the elements, heating/cooling cycles etc, and that perhaps foaming them early on in their lives inhibits them in some way, "breaking in" or some such thing...
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My van was white but is now grey.
Also, it has not gone through any temperature cycles since being foamed.
Been high centered in the shop all winter, being converted.
 
Cole

Cole

OUTLAW SPRINTER!!!
I would think a closed cell foam would expand and contract based on elevation changes. Just like a bag of chips. Home contractors don’t experience this since homes stay at the same elevation forever.

I suppose you could lessen to overall effect by spraying the van at 6,000ft. That way you’re about half way between the highest and lowest roads in the US. ��
 
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FMMM

Member
Jmolan said:
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?
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Jmolan said:
a lesser/slower expanding kind in the tight spots
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Can you tell me/anyone know what the "lesser/slower expanding kind (of foam)" is?
 
F

FMMM

Member
Midwestdrifter said:
A pro spray foam contractor can adjust their mix (or swap the mix) to change the rise rate in some cases.
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Hoping to try DIY i.e. rigid PIR boards where possible and then foam where not possible to use boards -- not opposed to a contractor though so might check locally.
 
T

Travelvanbuild

New member
A more likely theory is that the metal skin warping is caused by good insulation of spray foam in the up and low areas. With good insulation, the inside metal structure has much lower temperature than the external skin, especially if it is dark color and under summer sun. The external skin expands more than internal metal structure and warping happens as the result of different thermal expansions. Without good insulation, such as in a regular cargo van, the temperature difference wouldn't be that big so no warping would happen. This also explains why the large areas (fewer metal support) would have less warping with spray foam.
 
F

FMMM

Member
Travelvanbuild said:
This also explains why the large areas (fewer metal support) would have less warping with spray foam.
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Bit unfortunate i.e. since you can avoid warping in accessible areas by using glue on foam roll insulation - no warping with that - see @Graphite Dave posts.

Think Dave suggested heating the spray on foam (can) in hot water - Dave have you sprayed the internal sections of the ribs etc. and did they warp?

Think I read somewhere that some folks use spray on antirust "wax oil" type products - then spray on foam (can). But I'm guessing that the foam would just fall off ---?
 
G

Graphite Dave

Dave Orton
FMMM said:
Bit unfortunate i.e. since you can avoid warping in accessible areas by using glue on foam roll insulation - no warping with that - see @Graphite Dave posts.

Think Dave suggested heating the spray on foam (can) in hot water - Dave have you sprayed the internal sections of the ribs etc. and did they warp?

Think I read somewhere that some folks use spray on antirust "wax oil" type products - then spray on foam (can). But I'm guessing that the foam would just fall off ---?
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Did the Sprinter insulation 20 years or so ago. Tried to eliminate all air space between the insulation and the metal roof. Think I used 3M 90 to glue the pieces of rigid insulation to the metal. Left gaps between the insulation pieces and cut off the corners so there was a hole at the corners. Filled the gaps and the corner holes with spray foam. Did find that spray foam expanded better when warm. As I recall I did fill the ribs with spray foam where I had holes for access. Did not have any warping.

Filling the holes above and below the window indents with many small pieces of rigid insulation was tedious, On Transit build I insulated above and below the window indents with two layers of flexible 1" Aerocel closed cell foam. Closed cell foam can be folded to get through the openings and then opened up to glue. Much larger pieces can be used. Also used the Aerocel for curved roof areas.
 
F

FMMM

Member
Graphite Dave said:
Closed cell foam can be folded to get through the openings and then opened up to glue. Much larger pieces can be used. Also used the Aerocel for curved roof areas.
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Apologies I'm not good at this DIY stuff - can you e.g. push a bush through the holes (even in inaccessible places) and glue institute?


Graphite Dave said:
Left gaps between the insulation pieces and cut off the corners so there was a hole at the corners. Filled the gaps and the corner holes with spray foam.
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May be much cheaper for me to use rigid insulation boards in large relatively flat areas [compared to Aerocel closed cell foam (rolls)]
So you can use rigid insulation and seal it using this technique?

Thanks
 
3Play

3Play

Well-known member
My T1N warped a little some time after it was sprayed. I did all the pillars and beams with canned foam and a friend with a pro rig did the majority of the van. it's about 1.5 to 2" The foam does continue to expand a little after the initial cure, heat seems to make it more pronounced.
The warpage is minimal, I only see it if I park under a light at night.

If I didn't have a friend who sprayed foam, I would have done the hard to reach places the same way with cans, then glued in 1" and 1/2" PE foam sheets and sprayed around the edges. This is just as effective as expensive foams and a better sound dampener. 9'x 4.5' sheets of 1" are only about $35. the 1/2" are $16-ish. it takes about 2 to 3 sheets of each to get 1.5" on all the large fields. The whole van can be done for about $200 including canned foam.
It's flexible and you can cut it with a kitchen knife...
 
F

FMMM

Member
3Play said:
The whole van can be done for about $200 including canned foam.
It's flexible and you can cut it with a kitchen knife...
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Wow. I'm in Northern Ireland (part of UK) and there's no way I could used the equivalent of Aerocel closed cell foam (25mm/1") for that price ---.
 
3Play

3Play

Well-known member
FMMM said:
Wow. I'm in Northern Ireland (part of UK) and there's no way I could used the equivalent of Aerocel closed cell foam (25mm/1") for that price ---.
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I am referring to a polyethylene foam that is used for packing material. It comes in white and charcoal grey in various thicknesses.
it gets crumbly if left in the sun, but does well behind walls...
 
G

Graphite Dave

Dave Orton
FMMM said:
Apologies I'm not good at this DIY stuff - can you e.g. push a bush through the holes (even in inaccessible places) and glue institute?



May be much cheaper for me to use rigid insulation boards in large relatively flat areas [compared to Aerocel closed cell foam (rolls)]
So you can use rigid insulation and seal it using this technique?

Thanks
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I used spray foam inside the ribs and used the Aerocel closed cell foam above and below the window indents. The Aerocel works very well conforming to curved surfaces.

A picture below of how I used rigid insulation with joints and corner spray foam. Picture is in window indents but used the same procedure for the flat roof areas. Used the rigid in rear indents to maximize the bed length. Picture is in a Transit.

100_1495.JPG | Walls (ortontransit.info)
 
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