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I'm using the 1" thick r5 foam board, I started gluing an forgot to measure the depth ribs in the van where ill be installing my wood walls to cover it up. iv got about 3/4" gap between the insulation and where the actual wall will be. will this cause a problem for moisture or anything ?
i will have the same problem with the roof seeing as its 2 1/4" depth from the van wall to the edge of the ribs.
The gap itself is not a problem if you have a completely sealed up moisture barrier that will prevent any moisture getting into the gap. However if warmer than the dew point moisture does get into that gap then it will develop condensation on the below dew point temperature metal surfaces.

For anyone who is seeking to understand this physics issue just do some edcational, internet research with the keywords....dew point condensation moisture barrier. That will help you understand how condensation happens and what can be done to prevent it. Those types of articles include illustrations and pictures are worth more than a thousand words in a forum posting.
so basically i have to put in a moisture barrier then on to of the insulation if theres going to be a gap.
Pretty much that is how it works. If moisture in the interior air hits the cold metal that is dew point or below in temperature it will condense. It will also do the same thing to the window glass. Or you can look at an alternative insulation that is adhered directly to the metal surface since that is both a moisture barrier as well as insulation.
I get the dew point stuff but I am not sure if it was me that I would worry too much about this gap, the ribs are metal so you will be moving cold air through them anyways, it is not as easy as in a house to stop all the condensation from forming, the best I think you could do is have good ventilation, opening windows and or vents, not use too much non vented propane and if possible use some kind of dry heat heater, vented propane, deisel or wood. If it is easy to put in a vapor barrier then by all means, I am sure it will help,
Use non expanding spray foam to fill thhe void. Easy & then it's done right.
(02-24-2019, 01:43 AM)flying kurbmaster Wrote: [ -> ]I get the dew point stuff but I am not sure if it was me that I would worry too much about this gap, the ribs are metal so you will be moving cold air through them anyways, it is not as easy as in a house to stop all the condensation from forming, the best I think you could do is have good ventilation, opening windows and or vents, not use too much non vented propane and if possible use some kind of dry heat heater, vented propane, deisel or wood. If it is easy to put in a vapor barrier then by all means, I am sure it will help,

ya i plan on keeping the windows open and always have some sort o wind flow going threw the van as much as possible. how ever i did stumble across this thread https://faroutride.com/condensation-mois...lUrL2npYC4
and it gives some pretty good insight, so i may pull out the little bit of foam board i have now, and buy rockwool boards, they are 2 inchs and i can just lightly compress them with the wall, this will help with the gap i think.
I posted somewhere elso on here to use Thermax as it's fire resistant & if you're asleep & a fire starts it's the fume that kill you before the fire does. Most non expanding spray foam won't burn wither.
(02-24-2019, 01:43 AM)flying kurbmaster Wrote: [ -> ]I get the dew point stuff but I am not sure if it was me that I would worry too much about this gap, the ribs are metal so you will be moving cold air through them anyways, it is not as easy as in a house to stop all the condensation from forming, the best I think you could do is have good ventilation, opening windows and or vents, not use too much non vented propane and if possible use some kind of dry heat heater, vented propane, deisel or wood. If it is easy to put in a vapor barrier then by all means, I am sure it will help,
I highly recomend the deluxe chinese (same place espars are made) , comes with all the parts you could ever need diesel 5kw heater with the digital contril & key fob controller you just point & shoot. Shipped &  got it in 2 dayscan't wait to install it.
(02-24-2019, 04:48 PM)Gr8ful Wrote: [ -> ]I highly recomend the deluxe chinese (same place espars are made) , comes with all the parts you could ever need diesel 5kw heater with the digital contril & key fob controller you just point & shoot. Shipped &  got it in 2 dayscan't wait to install it.

You shouldn’t be recommending something you haven;t even taken out of the box. It may very well be the best heater ever made for the lowest price, but you won;t know that for some time yet. Comparing it to an espar is a bit unfair to Espar as well as to the readers of this forum. Just because it’s cheap, has a lot of new shiny bits and arrived on time should not rate in highly recommended heater category. It may well get there but not as long as it is still in the box.  No one rates a new car by looking at their reflection in the chrome.
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