The varieties and qualities of insulation have changed a lot in recent years. For example, some spray foams expand very little because of complaints about ones that expanded so much they caused problems such as distorting vinyl windows. I have no idea about spray foam turning to dust, but perhaps newer ones don't do that.
Polyisocyanurate panels have been available for some time and have different qualities depending what you order. I'm not sure what you can get at places like Lowe's, but building supply stores should be able to advise you about what is available. Foam panels should be available with much better R value than the fiberglass Airstream uses. The hard part about foam panels is making exact fit because it's the air spaces that are the problem. The best insulation isn't worth much if there are air spaces and that's why people love spray foam. I like the idea of using aluminum tape. The metal ribs transmit so much heat, it's hard to insulate these trailers really well.
Streamline also used spray-in insulation by about 1970; it'd be nice to see how well or poorly this method worked if anyone has seen the interior panels of a Streamline or Avion. I'm guessing, based on the above comments, that it was not so effective long-term, but, still, it would be nice to put the idea to rest (short of modern-day alternatives).
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Just was at a home expo. They had a soybean based spray foam 100% edible!!! They had pieces of it you could taste (I passed) and NO there was no smell to attract rodents!!!
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I've seen this product used on the Green channel (my new favorite channel) on dish network. I think it was on one of the "Living with Ed" shows. (Ed Begley Jr.) It was awesome...for homes! Besides all the good things about the foam it has a good R rating as well.
Quote:
Originally Posted by DIMMER
Just was at a home expo. They had a soybean based spray foam 100% edible!!! They had pieces of it you could taste (I passed) and NO there was no smell to attract rodents!!!
Has anyone thought of using bedliner material over the interior of the outside skin and ribs to seal the gaps and seams? It bonds really well and is flexable. Just a thought.... Or a brain fart......
To most effectively stop leaks you really need to stop them completely on the outside of the vehicle. If the moisture can wick in between the aluminum sheets, or worse between aluminum and steel components, filiform corrosion is not far behind. Once the water starts inside it continues inside.
There could be a corrosion problem with applying the truck bed liner over aluminum. The product is made to go over painted steel. I would contact the manufacturer of the product prior to application; you certainly wouldn't want to cause any further problems.
There are already several products made specifically for making these modifications that have been proven over several years of service. Acryl-R, SikaFlex, and Parlastic are just a few. These products are available at many locations including Airstream.com and your local Airstream dealer.
Brett http://www.TimelessTravelTrailers.com
We like to stick to proven methods when we work on a client's coach. We do take innovative approaches and use new materials on a frequent basis. However, we spend a great deal of time in research and/or testing before we apply these solutions to client's vehicles.
Johns Manville makes polyisocyanurate board--usually 4'x8' sheets in varying thickness. Thermax is another made by Dow that comes the same way. I'm sure if you did some internet sniffing you could find something suitable to fit your requirements. I would suggest 1/2 inch thickness and also make sure you get the foil tape for all the joints.
Polyiso foam typically has an R value of about 7.5 per inch. To maintain the same insulation value as the original fiberglass you should install at least 3/4 inch. A full 1 1/2" thickness will improve thermal efficiency. The seams should be completely taped with aluminimum tape to create a vapor barrier. The disadvantage to the thicker foam is that you will have to carve an occasional path for wiring but if the wiring is planned before installation, the carving can be held to a minimum.
We have had two trailers in for segment replacement in which someone had installed spray foam for insulation during a restoration. In both cases the foam was very well bonded to the interior and exterior skins. In order to replace the damaged segments we had to disolve the foam using nasty chemicals. In one case the insurance company totaled the trailer rather than paying the cost to remove the foam. We also noted that there was heavy filiform corrosion on the backside of the aluminum in the places where water could accumulate.
We insulate with Polyisocyanurate foam panels to achieve about R-12 in our projects. The panels are faced with aluminum which allows us to use aluminum tape to form a sealed vapor barrier and keep the moisture away from the skin. We order a specific type of polyiso foam which contains a high number of glass fibers and a high carbon black content. The glass and the foil keep the foam from breaking down into the "dust" others have described. The cabon black significantly reduces the flammability of the foam. It is waterproof.
While "polyisocyanurate" is a terrible sounding name the product is quite green. It does not contain formaldahyde. It does not off-gas nasties into your confined cabin environment. In the event of a fire it does not off-gas toxins.
The main draw back is that it requires about 3 to 4 times longer to install than fiberglass.
Fiberglass is frequently treated with formadahyde to prevent mold formation and rodent and insect infestation. In year round use in cold climates fiberglass can become water laden through condensation and loose all of its insulating qualities.
The repair crew at the factory also said trying to replace panels and segments was just awful when expanding foam had been used. BUT then I had a thought (dangerous AND remarkable, I know) When I got my new one, it was very obvious that the interior panels had been covered with a tightly adhered plastic film that was removed AFTER the inside panels were pop riveted on. I probably spent a week pulling the leftovers off from behind the rivets. So if the aluminium comes from the factory with plastic to protect from scratches, why not leave it ON on the inside of the exterior skin and then adhere the foam to that. I wonder if Airstream would consider doing that.
Oh, BTW, also remember there have been a few people on the forum who used the foil bubble insulation spaced away from the outside skin with styrofoam spacers... that seemed to work very well. I haven't seen those threads for a year or so. Perhaps someone who did it can report on the long term effectiveness.
Paula
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Ok I have to admit I used expanding foam around my HW heater it was smaller than the HW heater I had, so I filled in the sides to make it air tight. This foam is rubberized type will not go solid I hope I wont have the problem described .. ... Ill let you know.
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I am wondering if anyone has used open or closed spray foam insulation in their trailer. I am speaking of the professionally applied foam such as Demilic Sealection. In construction we use it to insulate and it is trimmed with shears after being sprayed in place. The closed cell insulation is obviously mostly water impermeable so I am not sure how that would affect things, although the R value for closed is R7 per inch. I think the R value of open cell is R3 or close to that. Although the performance value is higher. If I am not mistaken, open cell foam is R27 performance wise on a 3.5 inch stud wall. We don't use closed cell on exterior attics and walls because it would not let moisture out.
So just wondering if anyong had any thoughts!
Chris Crimmins
There seems to be quite a diversity of opinion on this topic but if anyone mentioned the differences in open cell or closed cell foams, I must have missed it. I have a 1972-27' Overlander ready for insulation and have been trying to do my homework, as well. Perhaps you might want to start with an excellent article in Fine Homebuilding #204, July 2009. Of course, an Airstream is not like a stationary house but checking out all the references in this very complete article, you will find vendors who use spray foam insulation in refrigerated trailers and other applications. There was no mention of the insulation turning to powder. To be sure, the spray-in insulation of the late 1960 and 1970s is not the same stuff as that available today, fortunately. Today's product is chemically inert, will not grow or support mold growth (as will fiberglass), will not evolve formaldehyde, etc. There is a huge difference in open cell and closed cell foams with the latter being a much better performer in terms of application and final R-value. Closed cell foams, when fully cured, end up with an R-value of a bit less than 6 per inch. There are several DIY foam kits available online and mentioned in the Fine Homebuilding article. The most economical seems to be Tiger Foam. For my 27' Overlander, I have calculated that the number of "board feet" of volume required for the job is about 358. That would provide a 1" layer overall. The kits come in 200 and 600 board foot amounts, with the larger quantity a significant value. A full 600 board foot kit would completely fill the wall space in a 27' Overlander and cost about $610.
Like you, I've got to do lots more research but what I've found looks quite promising. I even spoke to an Airstream dealer who repair lots and lots of Airstreams. His comment was that spray-in foam would be an excellent insulator. He made no mention of it turning into a powder. From my experience, I suspect that the foam-to-powder transformation occurred with an open cell foam.
There seems to be quite a diversity of opinion on this topic but if anyone mentioned the differences in open cell or closed cell foams, I must have missed it. I have a 1972-27' Overlander ready for insulation and have been trying to do my homework, as well. Perhaps you might want to start with an excellent article in Fine Homebuilding #204, July 2009. Of course, an Airstream is not like a stationary house but checking out all the references in this very complete article, you will find vendors who use spray foam insulation in refrigerated trailers and other applications. There was no mention of the insulation turning to powder. To be sure, the spray-in insulation of the late 1960 and 1970s is not the same stuff as that available today, fortunately. Today's product is chemically inert, will not grow or support mold growth (as will fiberglass), will not evolve formaldehyde, etc. There is a huge difference in open cell and closed cell foams with the latter being a much better performer in terms of application and final R-value. Closed cell foams, when fully cured, end up with an R-value of a bit less than 6 per inch. There are several DIY foam kits available online and mentioned in the Fine Homebuilding article. The most economical seems to be Tiger Foam. For my 27' Overlander, I have calculated that the number of "board feet" of volume required for the job is about 358. That would provide a 1" layer overall. The kits come in 200 and 600 board foot amounts, with the larger quantity a significant value. A full 600 board foot kit would completely fill the wall space in a 27' Overlander and cost about $610.
Like you, I've got to do lots more research but what I've found looks quite promising. I even spoke to an Airstream dealer who repair lots and lots of Airstreams. His comment was that spray-in foam would be an excellent insulator. He made no mention of it turning into a powder. From my experience, I suspect that the foam-to-powder transformation occurred with an open cell foam.
BH
Spray in, spray on, foam is an excellent insulator.
But, only for something that doesn't move.
When an Airstream moves, it twists.
When the twisting takes place, it grinds that foam, to a powder, rendering it useless.
Dometic found out the hard way, and quit it, and so did Airstream.
Closed cell urethane foam won't absorb much water.
By the OEM specs a reasonable expectation is 97-99% closed cells after foaming reactions complete;
then add any abrasion or cutting of previously closed cells;
add in the thermal heave and shrink of Aluminum tearing cells;
add in vibration harmonics and oscillations from traveling cleaving foam bonds;
add in the flex from people romping and stomping;
And you have sponge waiting for condensation and leaks.
Fine, any insulation will be susceptible to humidity and leaks, but spray in is permanent, no hustling it out in a trash bag, cleaning the cavity and replacing...
I toured a project trailer with old spray in foam supporting many cultures, algae & bacteria & molds. The metals were rapidly disappearing where it existed, and the anguish of the restorer was plain to see. He recently called me asking if someone wanted a 30% complete 1969, the extra work foam caused staggered him back from the project.
OK,enough of the spray foam what is recommended for the floor ,my trailer came with maybe 1" insulation under plywood.I`m thinking of installing bagged 3.5 under the floor ,taping the ends,any imput. Dve
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... Ill let you know.
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