Volara insulation inside camper
I saw an earlier question re: potentially using Volara foam insulation inside a camper van, but I can’t find any conclusions to that conversation. If the poster is reading this (“smoojee”), I’m curious if you used it?
We plan to use it to create a thermal break in the interior of a teardrop camper (under construction as I type). So the “sandwich” is: Aluminum skin > HDPE (hard plastic layer sealed to aluminum skin > Thinsulate 600L > Volara > Maple hardwood veneer (Soystrong).
I am chemically sensitive, so I like the more healthy factors of Volara compared to other insulations you might use for a thermal break.
But in reviewing the issue of vapor permeability, it seems to rate as near zero. The question is: Will we be trapping moisture vapor in the wall that then can’t get back out? We need to ensure that the “sandwich” can breathe to the interior of the camper, since the exterior is well sealed (complete vapor barrier).
Should we only use it on the interior face of the aluminum framing, that is, as a thermal break? Or should we keep it as one membrane throughout, right below the plywood to prevent moisture vapor from even entering the walls (or to slow down its entrance into and exit from the wall cavity)?
I would very much appreciate any input on how to think this through. URL for Volara: https://www.sekisuivoltek.com/products/volara-polyolefin-foams/
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Replies
Caweeber,
If the Volara insulation is truly airtight, and is installed with carefully sealed seams, you probably won't have any moisture problems. But if the Volara insulation isn't airtight, and interior air gets past the Volara, then you'll get condensation on the aluminum skin of your camper in cold weather.
Thanks, Martin Holladay. I appreciate your input on this. That makes sense. We can try to make sure the folks who are building it make the Volara insulation air tight. Just thinking through the other option: Do you think the opposite approach, of using Volara only as a thermal break (so in some parts of the wall/ceiling but not others) would allow for more breathability and prevent moisture from getting trapped? We have 1 1/2" of Thinsulate in the walls, so it's not a lot of insulation to prevent condensation if the wall sandwich were more open. To me, even if more "breathable," we might still get condensation on the walls. Do you have any insights on that scenario? Thanks so much.
Caweeber -
If I understand your question above to Martin, the answer is no, you can't make a camper assembly "breathable" in a patchwork fashion. You need a continuous air barrier.
Tiny homes and campers are pretty special in terms of hygrothermal management. You have such a tiny volume and very little hygric capacity that you really need to manage interior moisture keenly. That means ventilation or dehumidification or both, but how to do that for such a tiny space? In the winter or cold weather, that may be simply cracking a window to bring in cold dry air, but at that opening be prepared for surface condensation that you manage manually each morning.
Peter
Peter,
Thanks so much for weighing in. I greatly appreciate your thoughts on this. I guess I'm just concerned that they won't be able to create a *tight* seal around the Volara, so I thought not having it between the Thinsulate and the hardwood veneer at all might be better (except as thermal breaks, as mentioned, since the framing is aluminum). To clarify that approach: Would it be better to have the wall more breathable throughout than to use the Volara across all walls/ceiling (behind the hardwood plywood)?
We will have this fan: MaxxAir MaxxFan Deluxe. And can open windows. We also plan on using a small dehumidifier.
I guess the key is to not let moisture be driven into the walls. Is that the bottom line? And thus the Volara would help prevent that.
Appreciate any further thoughts you have!
Thanks much.