Hi,
I would not use XPS directly against the van skin, as the maximum service temperature of XPS is only 165F and the van skin can exceed this temperature on a hot day with the van in the sun.


Great Stuff is indeed a very good adhesive -- if you get it on your hands, you will be wearing it for a week


Gary

 

I forgot about that temp ....now that you mention it I think I saw 160 somewhere...what happens when it gets hot than that?

It is a white van....

 

Hi,


The only direct experience I have with exceeding the max serv temp with XPS was a case where I had an experimental solar water heating collector that used XPS. The XPS was covered with a black rubber membrane. The XPS under the black rubber looked like a freeform sculpture after it was in the sun for a while.
https://www.builditsolar.com/Experimental/pinkfoam.htm


Not sure what would happen in the case of XPS glued to the van wall with Great Stuff, but I would be worried that it would lose the bond with the van skin.
White helps, but, to me, it does not seem worth the risk.


Gary

 

Since Polyisocanurate is available and can take about 400º why would you use XPS? Great Stuff Gap’NCracks does great work just spray narrow beads vertically and hold it in with a spring board. BTW 1” on the walls is enough.

 

Local availability is the first issue and it's cold weather performance is the other.

I've got the room for more insulation so I look forward to over insulating

 

I haven't used the Great Stuff foam cans for a few years since I discovered that the Touch 'N Foam applicator guns and replaceable foam cans work SOOOOOO much better. These are available from Amazon or at your better hardware stores- the guns are about $30 and the foam canisters are around $15 each.

The gun offers a more controllable means of applying the foam, can be easily cleaned, and you get to put it on the shelf with a partial can and reuse it later. Better yet, the foam is more consistent in its expansion and density, dries more quickly, and appears to hold up better. It's made installing windows and doors more pleasant for me. The extra cost will be offset really fast if you need more than a few cans of foam to complete your job, and once you use a decent applicator gun you will never want to touch a spray can of foam ever again.

 

once you use a decent applicator gun you will never want to touch a spray can of foam ever again.

This is so true, you will be going thru many cans so get it up front.

 

mcNeill78, I did my entire 136” HT, even inside many ribs and doors with 1” polyiso glued in with the Gaps and Cracks and used 2, 14oz cans! What are you doing with the rest??
And Wankel7 "Local availability is the first issue and it's cold weather performance is the other.” Polyiso preforms better at any temperature than XPS doesn’t it? Whats the problem? It is a bit worse when the temp is about zero than at 140º but it beats about anything you can buy! Every H-D and/or Lowes seems to have polyiso. I have gotten it in AZ, NH, VT, ME, MA, KY no problem so I thought it was available everywhere????

 

Yeah I dunno...not finding it within 100 miles. But honestly after reading a few things about polyiso in the cold I would rather have xps and roll the dice on the 160F.

http://www.owenscorning.com/NetworkShare/EIS/10019950-FOAMULAR-XPS-vs-Poly-FAQ.pdf

 

hi there, can you tell me the exact "Touch 'N Foam" product you used?....there are so many on the shelf!

 

Please don’t buy any Touch’N Foam product. The can is a PIA and foam will be in all the wrong places and way too much too.
Buy this: [ame]https://www.amazon.com/Great-Stuff-Cracks-Sealant-Gloves/dp/B06WLLL11X/ref=sr_1_5?crid=E5LBQK6I6D7Z&keywords=great+stuff+gaps+and+cracks&qid=1554088785&s=hi&sprefix=great+suff+gaps%2Ctools%2C292&sr=1-5[/ame]

 

Please don’t buy any Touch’N Foam product. The can is a PIA and foam will be in all the wrong places and way too much too.
Buy this: https://www.amazon.com/Great-Stuff-...ff+gaps+and+cracks&qid=1554088785&s=hi&sprefix=great+suff+gaps,tools,292&sr=1-5

Thanks for the info !! that kit isn't available on Canadian Amazon, but looks like you can buy the gun and foam separately.

 

The vertical surfaces on a white van will never get to 165 F under normal exposure conditions at any locations in the US. So, you would be safe to use XPS in this situation. We do a lot of weathering where I work and the panels simply won't get that hot. The situation that Gary references - enclosed box, black backing can get very hot, over 100 C depending upon orientation. This type of situation is more along the lines of a solar cooker though, and not what the van surface will experience, especially a vertical one.

 

I bought a light colored VW Westy (1979 ish) that had a white top and heat drooping plastic trim around the windows. The previous owner told me it sat at San Diego airport for a few weeks out in the sun. He claimed it got to well over 150º in the van and his argument was the windows collect heat and over a few days of 100++ and nights near 100 the accumulated heat raises the temperature to that range. Since Polyiso won’t deform for sure, and it doesn’t absorb moisture due to the foil, and has higher insulating properties, price is too close to be an issue, so I don’t understand why anyone would suggest XPS is a good choice. Hey it’s your van put in whatever you want, we recommend something we know will be satisfactory, but really what do we know?.

 

I used the pink board I live in TX and have no issue with it. Try to pre-cut all your panels first before you start foaming. I used 1x2 furring strips, driveway fiberglass poles and tent poles as the spring boards to hold the panels up for the foam to cure. I used the 1/2" green board(king span) 25psi for the floor. It's at some northern lowes and holds up well.

 

Hi,
If you go back and search for some of the past posts on this subject on this forum, there are links to tests of actual measured temperatures on car bodies that are above 165F. It does happen.


There is no temperature cold enough that you will ever get into where the same thickness of XPS will outperform Polyiso. The Building Science site has the results from extensive testing on this -- go to their site and search for something line Polyiso vs XPS, or look up the link on my past post on this site. To get an accurate comparison you have to take into account the temperature throughout the thickness of the insulation, not just the coldest part next to the van skin. The testing referenced on the Building Science site does this.


Do you really trust Owens Corning to provide accurate comparison data on the XPS that they manufacture to the Polyiso they don't?



Gary

 

I don't fully trust any company but I have doubts that Owens Corning would publish a completely fraudulent document to sell foam.

I did find a document from the research company you recommend and everything points to polyiso r values taking a nose dive in the cold.

https://www.buildingscience.com/documents/information-sheets/info-502-temperature-dependent-r-value

 

So despite independent testing you prefer the Owens Corning data comparison that disagrees. The "nose dive” you talk about is mitigated as temperatures rise inside the insulation. Even with the “nose dive” polyiso is better according to independent testing than XPS. There is evidence the XPS is marginal in hot temperatures. But several posters want to instal it for no good reason I can think of. If you can’t find Polyiso you have no choice anyway. We have gone through this many times on this forum, we recommend a product we know will work well based on experience and research. Use what you want but please don’t make us go back through the same arguments we have made for 3-4 years.

Have you researched humidity and water vapor in the XPS? All foams absorb it and it degrades the R value and it may present an issue below freezing. Polyisocyanurate is coated with aluminum on both sides to prevent intrusion of humidity and offer a thermal reflective surface on both sides. Instal it with a dead air space and gain R value again. I could give a fig what you instal but I don’t feel we should ignore the opinion that XPS is as good when we know it is not.

Try these places: https://www.google.com/search?clien....9382!2d-84.82573909999999;tbs:lrf:!2m1!1e2!2m1!1e3!2m1!1e16!3sIAE,lf:1,lf_ui:2

 

Hi,

I don't mean to beat this to death, and if you are more comfortable with XPS, by all means go ahead and use it. But, just to try to clarify what I was saying before a little more...



Here is the link I mentioned for the testing shown on the Building Science site:
https://www.buildingscience.com/documents/information-sheets/info-502-temperature-dependent-r-value


If you look at figure 1, the Polyiso reaches an R value of 5 when the MEAN temperature of the insulation is about 30F. If you are going to maintain 70F inside the van, than a mean insulation temperature of 30F would mean an outside temperature of -10F. So, at -10F outside, the R value per inch of Polyiso and XPS are about the same -- at any temperature above -10F outside Polyiso is better than XPS.


Here is one link that shows measured temperatures on the outside surface of cars:
https://www.autogeekonline.net/foru...ow-to-articles-by-mike-phillips/51131-black-car-paint-temperature-full-sun.html


Some of the temperatures get above 165F, and while it was done on a warm 93F day in the sun, there was a 15 mph wind to provide some surface cooling -- you can certainly get worse conditions than this in real life. For example, I've been in 115F air temp with no wind in Las Vegas -- this would make for quite a bit higher surface temperatures. I think it's good to think about what the worst conditions your van will see in its 20 year life and try to be good for something a bit worse than that if you can.


Gary

 

Since to OP is talking about XPS on the wall, wouldn't the temperature of the metal be lower for a vertical surface vs horizontal one.

All the temps I've seem are done on horizontal surfaces.

I don't have the tool, maybe someone does and can do the comparison of the vert & horiz temps.

 

Hi,
If the elevation of the sun is 45 degs, then the angle of incidence with the roof and the wall facing the sun are the same -- both 45 degs.


If you are at a latitude of 40 degs(mid US), at the equinox, the max elevation of the sun at solar noon is 50 degs, so for most of the day the vertical wall facing the sun is getting more sun than the roof.
At the summer solstice, the max elevation of the sun is 72 degs, so for midday the roof gets more sun than vertical wall.


I guess other things may effect things, like vertical air currents along the wall?



When we get back home in a week, will take some measurements.


Sun charts are lots of fun: http://solardat.uoregon.edu/SunChartProgram.html
Gary

 

Don't forget being closer to heated roadway & sunlight reflection off concrete, surroundings, cars etc. can double up that late afternoon 112°F Kansas sunshine heat soak. Kansas? My first road trip I'd have sworn there was a lava flow in the cargo area. Mornings not so bad just that PM rush hour // evening furnace effect really tried cooking us.. .