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Is fiberglass bat insulation a bad idea for a campervan? I think it has a bad reputation here and on the sprinter forum, but is it deserved?
  • Some say it will absorb moisture. Any worse than 3M thinsulate? The fibers themselves don't absorb moisture, so it would be the air spaces. Seems like the thinsulate would be the same?

  • Some say it will degrade & turn to dust. True or an internet rumor?
I'm asking because I may hire a van converter to finish the ceiling and upper walls & he wants to use it.
 

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Is fiberglass bat insulation a bad idea for a campervan? I think it has a bad reputation here and on the sprinter forum, but is it deserved?
  • Some say it will absorb moisture. Any worse than 3M thinsulate? The fibers themselves don't absorb moisture, so it would be the air spaces. Seems like the thinsulate would be the same?

  • Some say it will degrade & turn to dust. True or an internet rumor?
I'm asking because I may hire a van converter to finish the ceiling and upper walls & he wants to use it.
I don't like it because it will hold moisture on the fibers of spun glass and act like a wet towel until air moves through it and finally dries it out. It tends to mat down when wet too and in house construction has proven to be a good surface for mold to grow on. Hein will know more about Thinsulate but one thing it has going for it is it will not hold the liquid water and will let it move down through due to its Hydrophobic property. Glass fibre will not degrade over time as it is just fine strands of glass which are very flexible. All woven fibres that are not encapsulated tend to attract and hold dust which will enter the van walls from the holes along the pinch weld on the bottom and through openings like the air escape flaps at the back. This is not to be avoided anyway. The thing fiberglass has going for it is it is CHEAP. Thus the motivation for using it by installers. Disclaimer: I have only one experience using fiberglass in vehicles but much in homes.
 

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papab,
I stand corrected on the fiberglass being hydrophobic, thanks- I won't spread that myth anymore. (EDIT I just reread my post and I didn't say fiberglass was not hydrophobic just that it fills with water and mats down- which it does. If pushed I would have not known it is hydrophobic... ah well.) My mistaken belief is from pulling wet matted insulation from the bottom of walls of a building and literally being able to wring moisture from them. The building was a high humidity structure with no internal vapor barrier and painted sheathing on the outside. The sheathing was mold filled, as was the fiberglass and the sill was rotted as was the sheathing and the internal sheet rock was soft, degraded and had surface stains. In the vehicle I removed it from it was slumped into the bottom of the sidewall, wet and rusty as was the drain channel due to its having matted and closed off the drains. These situations have no way for the fiberglass to dry in any reasonable time. You are doing due diligence, good for you.
 

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papab,

If your converter wants to use fiberglass insulation it's time to look for another converter. Fiberglass is the worst thing you could use in an RV for all the reasons stated above plus the fact the particle tend to settle in a vehicle. Just because something is cheap and easy to use doesn't make it suitable.
 

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This link doesn't address moisture issues but I found it pretty informative https://www.youtube.com/watch?t=156&v=zzD1TPJq_OQ
I think that the term "dead air space" is poorly understood and assumed to be present where it is not. An example is attic insulation and wall insulation in homes. Often the ceiling of trussed buildings is filled (from below) with 10-16 inches of fiberglass batts and a vapor barrier is added below. Dead air space? NO! The air is free to move through the batts from above in the crawl space between the trusses. The R value of the insulation is severely compromised. In Walls the air is allowed to chimney up the batts with no firestops installed. Dead air? Of course not! Fiberglass batts work if all 6 (count 'em) sides are encapsulated with an air barrier and walls have no more than a few feet of vertical between barriers. At least one side of these barriers must be a non vapor barrier to allow the air in the dead air space to free itself of the inherent vapor content of air.
In our vans we get the vapor free barrier by not putting a vapor barrier towards the interior- as the exterior is a vapor barrier (steel). Fiberglass is a poor choice because the condensation produced on the vans interior surface is not vapor but is liquid water and unless it is re-evaporated and allowed to drain it remains in the insulation as liquid and corrodes the van, mold and mildew grows on its fibers as dust accumulates. Solid sheeting, non-absorbing panels (like Dow Tuff R) attached to the van's exterior with a small space to allow draining seems like a good choice. The foam can be sprayed-in place foam as well since the surface of the steel is not going to have vapor laden air against it there will be no condensation, no liquid and so no problem. The reflectivity barrier is not going to do us much good except to seal the insulation against absorbing moisture in our application as we cannot easily produce a dead air space.
 

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My first class B was a coachmen. I had it about 10 years. It has fiberglass insulation and worked well and never had a moisture or rust problem. My second van was a sprinter I converted myself. I used fiberglass insulation and had it for about 10 years. I stripped it before selling it and there was not problem with the fiberglass. No moisture or rust or other problems.

I put fiberglass in my new Promaster and home it gives me good results also. There may be better insulation but the fiberglass seems to work pretty good and is easy to install and cheap. It seems to have good sound proofing qualities.

Just completed a 3300 mile trip and stayed in several rv parks. I have added toilet/shower combo, sink, micro, etc. Sleeps 2. One bed folds up to a seat for traveling and I have added seatbelts for two passengers. 2500, 159 inch wheelbase. The Promaster is the best van ever. I had many vans of various brands in my business before I retired and nothing comes close to the Promaster. Averaged 18.1 MPG on the highway and 16.9 combined.
 

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My first class B was a coachmen. I had it about 10 years. It has fiberglass insulation and worked well and never had a moisture or rust problem. My second van was a sprinter I converted myself. I used fiberglass insulation and had it for about 10 years. I stripped it before selling it and there was not problem with the fiberglass. No moisture or rust or other problems.



I put fiberglass in my new Promaster and home it gives me good results also. There may be better insulation but the fiberglass seems to work pretty good and is easy to install and cheap. It seems to have good sound proofing qualities.



Just completed a 3300 mile trip and stayed in several rv parks. I have added toilet/shower combo, sink, micro, etc. Sleeps 2. One bed folds up to a seat for traveling and I have added seatbelts for two passengers. 2500, 159 inch wheelbase. The Promaster is the best van ever. I had many vans of various brands in my business before I retired and nothing comes close to the Promaster. Averaged 18.1 MPG on the highway and 16.9 combined.

Will you please create a build thread?! Would love to see your work


Sent from AutoGuide.com Free App
 

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Unless I read the description wrong the eBay seller is offering 1" thick insulate and Hein sells 1 3/4" thick insulate for only a little more. I paid about the same for 20 feet. All things considered his is much better for the price, imho
 

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papab,

If your converter wants to use fiberglass insulation it's time to look for another converter. Fiberglass is the worst thing you could use in an RV for all the reasons stated above plus the fact the particle tend to settle in a vehicle. Just because something is cheap and easy to use doesn't make it suitable.
Airstream does and has used fiberglass insulation for many, many years. Don't believe me? Just go to their Jackson Center, Ohio factory and take the tour.

Their is a lot of misinformation being presented on this forumn.
 
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