Questions about styrofoam for insulation

[DudeInAVan]

Apologies if this has been covered somewhere but I've been reading past threads on using styrofoam boards for insulation, and can't find clear answers to the following questions:<br><br>1. Should the foil-backed side face the inside or outside of the van?<br>2. What do folks use to hold the styrofoam boards to the walls of the van -- some sort of adhesive?<br>3. Does there need to be an air gap on either side of the styrofoam, or can it be sandwiched snugly between the van's body and the interior paneling?<br><br>Thanks!

 

[akrvbob]

On mine, I put the foil side into the living area. My thinking was it would be a better vapor barrier. I also did not put up any covering so the shiny side reflects a lot of light making the van brighter.<br><br>You can use glue to attach it. Or you can run 1x3 boards the length of the van at the top and bottom of the wall (screw them into the rigs with sheet metal screws) and screw the styrofoam into the 1x3s. If you are covering it with paneling, the paneling will be the outside. If no paneling, use wide washers on the outside of the screws to keep the styrofoam from pulling through. <br><br>I've never left an airspace, to the best of my knowledge it isn't necessary. An airspace is critical with Reflectix, but not with styrofoam. <br><br>Insulating the roof/ceiling&nbsp; is more important than the walls since heat rises and goes up through the roof. Buy thin sheets of styrofoam 1/2 or 3/4 because it will bend to the shape of the roof. Add multiple layers to get enough. Keep it up there by bending it and then putting up the top 1x3 along the wall to hold it in place. After the styrofoam is up on the ceiling, you may need to run another 1x3 in the middle of the roof running the length of the roof front to back to keep it up there. Use sheet metal screws into the ribs to attach it.<br>Bob

 

[peacetara]

I used Silicone to attach it, I found every other kind of glue just ate the styrofoam.<br><br>I put the shiny side OUT, and had the kids paint/color/marker all over the white side.<br><br>I can't speak for which side is better facing inside or not, but I think I'd go crazy with all that shiny staring me in the face all day. <img src="/images/boards/smilies/smile.gif" border="0" align="absmiddle"><br><br>With Love,<br>Tara

 

[MrNoodly]

I was researching this last night. I found some interesting info on a site for van owners who were more interested in customizing and short term camping rather than full-time living. One guy said that most adhesives give off moisture and solvents as they dry. The moisture will find the easiest way to escape. So, say you glue foil backed insulation to a painted van wall. The paint is more permeable than the foil, so that's where the moisture and solvents will go, which can lead to the steel beneath rusting/corroding. One solution is to not glue anything to the van less absorbant than paint. The other is to use specially formulated adhesives, like M-1.&nbsp;<strong style="font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; text-shadow: none;"><span style="text-shadow: none;"><a class="smarterwiki-linkify" style="text-shadow: none;" href="http://tinyurl.com/d28ftkc" rel="nofollow">http://tinyurl.com/d28ftkc<br><br></a><span style="font-family: Verdana, Arial, Helvetica, sans-serif; font-weight: normal;">As far as the&nbsp;</span><strong style="text-shadow: none;"><span style="text-shadow: none;"><span style="font-family: Verdana, Arial, Helvetica, sans-serif; font-weight: normal;">foil backing goes, there's this:&nbsp;</span></span></strong><strong style="text-shadow: none;"><span style="text-shadow: none;"><a class="smarterwiki-linkify" style="text-shadow: none;" href="http://tinyurl.com/cuvbfxa" rel="nofollow">http://tinyurl.com/cuvbfxa<br><br></a></span></strong><span style="font-family: Verdana, Arial, Helvetica, sans-serif; font-weight: normal;">Consider this: metals transmit thermal changes easier than nonmetals -- foam for example. If you glue the foil to the steel, the outside temperature passes easily through the steel and into the foil, thereby making the the foil essentially useless. Foil facing in helps keep desired heat or coolness inside the van. <br><br>Concerning air space, the foam <em>is</em> the air space -- zillions of little bubbles of air. That's how insulation works.</span></span></strong><strong style="font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; text-shadow: none;"><span style="text-shadow: none;"><a class="smarterwiki-linkify" href="http://tinyurl.com/cuvbfxa" rel="nofollow"><span style="text-shadow: none; color: #000000; font-family: Verdana, Arial, Helvetica, sans-serif; font-weight: normal;"><br></span></a></span></strong>

 

[DudeInAVan]

Thanks for the great info, everyone!

 

[MrNoodly]

Oh, and many adhesives eat away at styrofoam.

 

[CarCampire]

I believe you're speaking about the 1/2" or 3/4" (white) styrofoam with a thin foil layer on one side...<br><br><img rel="lightbox" src="http://s8.postimage.org/hwf0lvmc1/IMG_1673.jpg?noCache=1356234275" class="bbc_img"> <img rel="lightbox" src="http://s12.postimage.org/ido0wyhfd/IMG_1669.jpg?noCache=1356234422" class="bbc_img"> <img rel="lightbox" src="http://s8.postimage.org/ly17c6xg1/IMG_1671.jpg?noCache=1356234602" class="bbc_img"><br><br>So from my experience with the stuff-<br>1. I would suggest having the foil-side face the interior of the van. If you later cover it with wood paneling or something else (coroplast or corrugated plastic is lighter and ads a little more R-value + extra vapor barrier)- you should leave 1/4" spacing between the wood paneling or coroplast. You should also seal the edges around your inner walls with 100% silicon all around to confine any moisture and also; 100% silicon is the only adhesive-like calk that I hear doesn't eat the Styrofoam.<br><br>2. For framing and spacing I would suggest 1"x1" (if you can find them their ideal!) or 1"x2"'s - PRE-DRILL screw holes in them so you don't split the wood and VERY CAREFULLY secure them to the walls of your van without breaching the outer metal skin. Once you have your framing in place - place the styrofoam inbetween it - cutting it with a 'box cutter' / exact o knife - fill in any gaps against the studs and styrofoam with 'great stuff' for small cracks. This will insure nothing get's behind the styrofoam and also fill in any holes you may have accidentally made while cutting it with a 'free hand' knife. I also hear - if it's not secured - the styrofoam will squeak against the van walls and make a terrible sound when theirs wind outside or your driving at high speeds. The more secure - the better.<br><br><br>3. You can also use the 1"x2"'s to leave a little gap inbetween the van walls and the styrofoam - might help with a little more insulation since trapped air is what insulations 'all about'. <img src="/images/boards/smilies/tongue.gif" border="0" align="absmiddle"> I don't believe you NEED to have a gap with styrofoam but it will help to have one for the reasons given above - less squeaking and more air trapped. <br><br>Good luck and let us know what you do. <img src="/images/boards/smilies/smile.gif" border="0" align="absmiddle"><br><br>

 

[MrNoodly]

Some info on different types of rigid foam insulation:&nbsp;http://www.homeconstructionimprovement.com/foam-board-insulation-values/