Spray Foam Insulation

[drewboy70]

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.

[Brett - TTT]

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.

Brett
www.TimelessTravelTrailers.com

[Foiled Again]

Originally Posted by Brett - TTT

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.

Brett Hall
Timeless Travel Trailers

Timeless Travel Trailers

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

[Mrcrowley]

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.

[bhpowell]

Originally Posted by chriscrimmin

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.

BH

[Inland RV Center, In]

Originally Posted by bhpowell

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.

Andy

[Wabbiteer]

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.

Just say NO to spray in foam.

[easyride]

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

[Inland RV Center, In]

Originally Posted by easyride

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

That thickness is fine, but leave any and all backing off.

The insulation must breathe.

Andy

[Wabbiteer]

Andy has great insight - the itchless style bagged insulation is great stuff, and the bag itself is perforated but not nearly enough to stand humidity and moisture it was never meant to see when correctly installed inside someones house. Remember towing the trailer in rainstorms and hitting standing water, windows - door -vents left open in wind storm downbursts, leaks. Once fiberglass gets wet it only takes two forevers to dry out, three if its in the tube rolls

Our trailers had 2" bat insulation laid over the frame and crushed down in place by the flooring. Not really duplicatable, and I wish I could rid the entire frame of that glass wick, I had floor damage six feet from the rear compartment where the crushed glass drew moisture along the rusting ladder frame rail.

What the fiberglass is especially good at is dampening sound - but after dealing with Norway Rat & Mouse nests under the floor I swore it off, out, away, gone, repeatedly. The Reflectix type bubble foil is transparent to sound, a similar product Prodex Products : Prodex Total Insulation : Insulation Wrap : Bubble Wrap Insulation : Insulation4less.com does dampen sound somewhat so I got the big roll.

Living in Minnesota I'm more concerned keeping heat in, the foil bounces heat back up almost three times better than bouncing heat down like air-conditioning the interior in Florida would need but it's still pretty good at R6 single layer.

I used foil-foam-foil Prodex with a 1/4 to 1/2 inch air gap - painted flooring for odor block and hygiene, put in single thickness Prodex 2-inch border strips at edges of frame cavities, glued & sealed the strips on both sides with Vulkem and fastened the cover layer of Prodex with monel rustproof staples, to get a larger airspace I set a small island of two layers of prodex in the center, attached the same. Sealing with polyurethane caulk made it a super neat job. I can also see using sheet foam, the fanfold 1/2" thick sheathing type, as another layer below the foil. That style foam is scissors cutable and easily set in...

[Brett - TTT]

The spray foam is a REALLY big problem if you every need body work. The foam sticks to the aluminum and will need to be disolved out of the wall with nasty chemicals before a segment or panel can be removed. This removal can add enough time and cost that an insurance company might total the trailer rather than repair it.

We had a 1969 Safari which someone had replaced the original under-floor fiberglass with spray foam. The chassis was badly corroded, in part from the water which worked its way between the foam and the steel and stayed there. In order to do any welding repairs we would have had to disolve large areas of foam with chemical solvents. It was decided to build an entirely new chassis to replace it.

Fiberglass in the belly is an exellent nesting and food storage place for critters. See our Common Defects page for some ugly photos. Fiberglass in the belly also collects gallons of water in wet or snowy driving conditions which, even in a dry climate. will take months to dry out in the relatively closed environment of the belly pan.

The mylar bubble wrap is fine for reflecting infrared wave heat but does very, very little for the prevention of thermal heat transfer.

In our rebuilds and new buildouts we use Polyisocyanurate closed cell, aluminum faced, board insulation of 1.5" thickness and tape the seams with an aluminum foil tape. Critters and insects will not burrow or nest in this material and it will not collect or hold water. If repairs are needed it is easy to remove. It can be scored on the backside and bent to fit in the compound curves of the upper body. In these locations we use the foil tape to make a complete seal to act as a vapor barrier which prevents the accumulation of condensation on the inside of the walls during cold weather use. In the upper bodies we also offer formaldehyde free fiberglass but it does not form a vapor barrier and will collect a great deal of water from condensation. Most people who can afford the polyiso foam board opt to install it.

About condensation during cold weather use: The water vapor travels throug the seams in the inner liner and condenses on the inside of the outer skin. It then soaks the fiberglass insulation which reduces the effectiveness of the insulation. It also runs down the inside of the skin to the sill and the plywood deck causing wood rot. Where does this much water come from? Cooking, burning propane in the cooktop and oven, local humidity, water vapor from showering, water vapor from washing dishes, and, the biggest contributor, people breathing. The average human body gives of 2 liters of water durning an 8 hour sleep period. We have had fiberglass insulated trailers come into our shop during winter use which have had to be dried out by bring them inside, raising the building temp, opening all of the trailer windows, vents, hatches, and doors and running large electric heaters 24 hours a day for two to three days.

We have the benefit of reverse engineering many trailers of all vintages each year and seeing the benefits and problems with many different methods of insulation methods, chassis construction, window design, maintenance, uses and operation which have been used over the years. With this experience we work with our vendors to come up with better methods and material solutions and attempt to solve the problems in the present and future.

[Aerowood]

One question Brett, Are you installing the polyico contacting the outer skin or spaced away.

Kip
Just up Ward from you.

[bhpowell]

With so many concerns about 2-part urethane, closed cell foam turning to powder in a trailer, I posed the question to Tiger Foam, who advertises on this site. The response from Allison follows:

BH,
I am not sure of other foams, but our foam will not turn to powder due to the motion of the trailer.
Allison

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Commercial Thermal Solutions, Inc.
800-664-0063 x1
877-415-1185 Fax
001 + 1.732-927-2090 International
001 + 1.732-927-2091 Fax
allison@tigerfoam.com
www.tigerfoam.com

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'Nuff Said


BH

[Brett - TTT]

Kip -

We install the polyiso between the inner and the outer skin. We do not intentionally pack it tight to the outer skin but incidnetal contact is unavoidable. The foam we use has thin aluminum layers bonded to each side.

The perfect install would allow an evenly spaced dead air space on either side. We opt for the minimum movement and the maximum vapor barrier effect.

For a simple test of how fiberglass holds water, take a small piece of it and dip it in a container of water.

[chriscrimmin]

Perhaps experimenting with a release agent on the skin being sprayed on would be ideal. It seems if there is no bond with the skin, closed cell foam will form after being shaved a much better fitting panel filling the crevices. If not adhered on either panels, it might make sense that the panel would float. At the same time, closed cell foam being impervious to water still has flex. It will move and adjust. If properly applied, a great foam job should get us 30-50 years anyhow of great insulation. Sounds like a plan, lets see i would be 82 by then. Sounds good!

[Wabbiteer]

Here is my 'Post' to no one in particular..

Lets go over this one more time, just for the health and hygiene aspect. This is NOT a hermetically sealed container to fill with foam like a surfboard or a thermos jug. This is an aging trailer that has seen life, the good and the bad, cycles of vermin and insects, careful housekeeping by bipedal hominids and spring break benders by wilding monkeys (sorry monkeys) with everything in between.

A fellow above mentioned a DIY kit provides 600 board-feet or 50 cubic feet of foam. At 99% closed cell that leaves 1/2 cubic foot of open pores which equals 3.74 gallons of water by volume. Okay, not all that volume is gas voids, the thin bubble walls account for some, and not all those open bubble cells will ever see humid air for condensation to occur or catch liquid water but those that do will never dry out, and the walls seperating open cells from closed can often be measured in molecular layer thicknesses, again not the armor we think of since it is such a microscopic scale so an 'open cell' is the gateway to a whole chain of voids.

I could go on about Nature abhoring a vacuum, the worlds micro-organisms attaching themselves, living in moisture pockets, or even feeding on the foam itself during the daily sun heating incubation bop. Or about the moisture attacking aluminum and iron. Or needing access to things, even with a release agent, and tearing the foam apart, or enlarging the moisture holding tendencies by cutting excess away or with every gouge, scrape and scratch.

Combine moisture, no/low fresh air (oxygen) no sunlight and one has a giant petri dish awaiting whatever is or has been in (the last 35 years on my trailer) the breeze down by the lake, on the freeway, sitting alongside the city alley, etc. and thats not counting black or grey tank slosh, sanitary hose storage, road kill lint, forgotten trash, sour ice-boxes, fish cleaning, pet dander, ad infintum. Maybe some brands of foam have been treated to not feed some molds, but the mold can simply lounge on it waiting for the next meal to be cooked to get a few whiffs of bacon grease, etc.

Sheet or roll foam or fiberglass that has enough airspace around it to 'breath' if/when moisture occurs is key, remember with 20~% Oxygen in the air around us it constantly bleaches every surface it touches.

Also - replacing simple fiberglass is a breeze if you don't try to do the whole trailer at once...

[ticki2]

Originally Posted by REDNAX

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).

FWIW
I am in the process of reviving a "68 Avion truck camper . It has original sprayed in insulation . I have not seen any sign of deterioration in the insulation or the inner or outer skin.

I also have an old military box trailer 1959 that has alum skins in and out with faom insulation sandwiched between. There has been no deterioration of the insulation or the inner and outer skin. This thing was built to travel where there were no roads and/or dropped from a chopper.

The technology has been around for at least 1/2 a century.

Cavity insulation such as fiberglas when installed properly should have a vapor barrier on the inside to prevent the moisture from the living space from getting into it , hopfully the outer skin is waterproof. It is not ment to breath , it is ment to stop air movement .

[bhpowell]

Originally Posted by easyride

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

That would probably work well. After treating my frame and trusses with the POR-15 system, I obtained some 1" thick and 2" thick extruded polystyrene foam sheet, cut it to fit the voids between the trusses.

BH

[FC7039]

For the record I too am considering using spray foam (closed). I am considering it for two properties. One is the void filling of the expansion, especially around windows, doors, hatches, vents, ribs and Olympic rivets where most leaking occures. The other property is its adhesion to the aluminum forming a seal. I would spray it with the internal skin off and not try to fill between walls.

On the show, How Its Made, they show Airstream sealing rivets and seams from the inside using what appeared to be a paste/caulk, probably polyurethane based (just a guess, please correct if you know). Why? Sealling the outside, good, sealing both the outside and inside, better.

I concede that no matter how much you seal and try to prevent water from seeping into seams and around rivets, it will eventually happen. The older the trailer the more it will happen. Either foam or caulk will loose adhesion over time, maybe one more than the other. I do not suspect it will fail all together and if it did I do not think once detached from what it was adhered to it would continue to crumble at an accelerated pace. Some (Overlander 63) say it will others (Brett TTT) say it adhears too well. I will also concede where ever the water sits, corrosion will happen. (You can treat the inside of your aluminum to help retard this corrosion).

The issue to me is what becomes of this water once it enters. If sealed from the inside, whether with a caulk or foam, the water will be contained near the point of entry. Without this sealing, the water will travel downhill once its weight is greater than its surface tension. This usually ends up in the channel sitting on the floor. All renovators of older trailers will tell you the condition of their channels and floor. I have a 59 year old trailer. Almost all the channel and the floor were rotten beyond reuse. Most of the internal skins have corrosion issues at the base. At some time a repair was made where a skin was riveted over the damaged skin. There was corrosion where moisture would form between the skins but not where the integrity of the skin was affected, mostly just cosmetic.

Back to water getting in, and it will, I know. I do not believe that if water can get in, it can no longer get out. Now I am going to speculate. If water can enter, maybe do to the internal void cooling causing suction, that when heated by the sun, expansion will happen and water will be expelled. I don’t know anything about what attracts mold (or any of God’s other microscopic creatures) and what repels it, but I don’t think that its toxic properties will migrate through the sealant and into the cabin. So it should only be exterior. Don’t lick your seams J

I am going to trust Tiger Foam and their claims about its toxic properties (or lack of them).

Bret –TTT makes a good point about the issues of repair. This is a first hand fact offered up in this discussion.

My thought is that I would spray the foam around all windows, doors, hatches, vents, seams and rivets. This would include the ribs and channels. I would fill the open areas with another type of insulation and now hearing of Polyisocyanurate (origin please, can you use it in a sentence, “The insulation of choice by some Airstream renovators is Polyisocyanurate.”) Hopefully should I need to repair a panel I can detach the foam from the damaged panel without solvents but by inserting a flat cutting tool into the seam.

I have not done it yet but have not been convinced by recent first hand arguments against it. I have made many mistakes and this may just be another.

Gene

[Wabbiteer]

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.

First hand? The sub-floor cavity looked like odd chunks of rust-brown & blackend Styrofoam left randomly at a high water line eddy in a nest of rusted iron spar twigs, just like an urban storm drain after the rain. Its a slippery slope, outdoor storage and/or one or two years missed maintenance and there is going to be trouble.

Good point about seams breathing - only trouble is they easily 'inhale' liquid via siphon and vacuum but have to 'exhale' vapor unless it pours straight through...

I understand there are many successful spray foam installations - if you start with new materials & methods that were all chosen for that particular installation ie: the Avion P/U camper or a mil-spec sandwiched panel, both of which are framed considerably stiffer than old Airstreams ever were. I wonder if the Tiger Foam people would buy a 2010 Airstream, or a 1970, just for the joy of retrofitting it

And about seams and Vulkem? I had factory caulking at/under the taillights holding liquid water, when I jacked up the rear bumper to level ladder frame and went to insert the flooring it squirted out at me like a clown-flower gag as the shell twisted from the tourqe. (I couldn't make this stuff up, I'm not that bright) . ...Old trailer caulking is not to be trusted!!

I'll shut up about it now. Good luck~!!