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Old 01-05-2013, 01:48 PM   #169
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I'm not convinced by the anti foam arguments since they are primarily anecdotal and there are so many different kinds of foam available. I've been reading about polyisocyanurate insulation and it is impressive. You can buy 1" or 1 1/2" thickness sheets from Home Despot for $20-30 http://www.homedepot.com/Building-Ma...1#.UOiPpny9KSM a 4x8 sheet so I am estimating $200-$300 for my 16' long shell. I may do the 1" thickness with the foil on the outside with a 1/2" standoff to the outer skin. That will provide an air gap that will help provide a radiant barrier toward the outer skin and a conductive barrier next to the inner skin hopefully to reduce condensation on the inner skin. I may do canned spray foam at the seams to try to create a continuous vapor barrier to further help with condensation. The 1" is R 5.9 and the 1.5" is R 9.4. I kind of like the idea of an outer 1/2" for venting and draining. With a couple of weep holes at the outside bottom of the C channel, water would have a place to go besides on my furniture.
One other thing about polyisocyanurate is that Timeless Travel Trailers uses it. Brett from TTT posts on this forum sometimes and I have seen them to be very conservative in their uses of materials. They used to build custom rail cars before airstreams-talk about constant vibration- so I think they know what they are doing.
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Old 01-05-2013, 08:13 PM   #170
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Since I haven't read those same insulation threads for about 16 months now, I don't recall the specific details, but I thought there were some pretty significant arguments against the spray foam. My recollection was concerns over the stuff falling apart in the walls due to vibration and rapid temperature changes as the metal expands and contracts, pulling away the bonds between the foam particles.

If I had to do it all over again, I would go with Darkspeed's ceramic insulator. I am sold on that stuff. I wish he was still around the forums to talk about it's road worthiness, but I would be willing to pay the money for it to give it a shot. I guess I'll wait for the next trailer.

The biggest thing I've learned for insulation is dead air is a problem in our trailer. When it has been 90F out but there is even a slight breeze, we open the windows and the trailer is nice and cool inside. When there is no wind and it is 90F out, it is upwards of 80F inside the trailer. We have one layer of 3/4" rigid foam as spacers (covering 50% of the area), one layer of reflectix, and on the roof we have the foam sandwiched between two layers of reflectix.

And re: keeping the ribs covered, I wish I could have done more of that. I was reusing hte existing metal, so I couldn't get even a single layer of 1/8" foam tape (which compresses to 1/16") on the ribs, or else the original skins wouldn't line up to the right holes on the interior. If I was installing all new metal, I would put thick cork everywhere.

Even without feeling the rivets, I could do blind tests with my hands on the trailer walls and tell you with exact precision where all the ribs are due to the extreme temperature differences. Pretty incredible.

Ok I think I'm done forcing my opinions down your throat. Good Luck!

Did you see this thread?
http://www.airforums.com/forums/f478...ide-86901.html

Basically FC7039 tested Darkspeeds magic coating and concluded that it actually trapped heat and would raise the temp in the trailer. Good for cold climates but otherwise not. I also wish Darkspeed had stuck around longer! He certainly thought outside the box!

I still don't think there's a magic insulation..... I'm currently looking for a thermal break for the ribs. I think the HSC might work for that.

I was talking to Colin Hyde once and remember him saying that he saw a severely corroded aluminum panel that was behind some spray in foam insulation. Probably the foam had trapped condensation right against the skin and the inability of the water to drain away or evaporate had made matters worse. Rest of the trailer was ok but the panel where the owner had spayed in foam was a mess.
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Old 01-05-2013, 10:46 PM   #171
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Did you see this thread?
http://www.airforums.com/forums/f478...ide-86901.html

Basically FC7039 tested Darkspeeds magic coating and concluded that it actually trapped heat and would raise the temp in the trailer. Good for cold climates but otherwise not. I also wish Darkspeed had stuck around longer! He certainly thought outside the box!

I still don't think there's a magic insulation..... I'm currently looking for a thermal break for the ribs. I think the HSC might work for that.

I was talking to Colin Hyde once and remember him saying that he saw a severely corroded aluminum panel that was behind some spray in foam insulation. Probably the foam had trapped condensation right against the skin and the inability of the water to drain away or evaporate had made matters worse. Rest of the trailer was ok but the panel where the owner had spayed in foam was a mess.
I am probably not going to use spray foam either, but I do think that one spray foam application with bad results does not mean that all spray foams are bad. There is a spectrum of different chemistry for spray foam and they will all behave differently. I am too cheap to do it but I bet that the right foam with the right application would be amazing. I don't want to debate spray foam on this thread since it has been discussed a lot in other threads, but I hope that the people who tried different types can report back and let us know what happens in real life. Thanks for sharing the info on the testing of HSC. I'm still looking for a thermal break for the ribs so any additional suggestions there are appreciated.
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Old 01-06-2013, 08:22 AM   #172
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Leaning towards the-foam-that-must-not-be-named myself, not the whole shell cavity but just the ceiling/roof where the angle gets within 45 of horizontal. I'll be treating the bare aluminum, then glazing everything by adding layers of bonding paint with insulation beads in it, then doing the insulation.

Problems any insulation types face: The pre-stamped rivet holes on the roof section that end up misaligned & unfilled every xx inches, relaxed rivets siphoning water in, windows/vents/seams puckered from travel & accidents or other oddities of 30,000 expansion & contraction cycles... all should be sealed from the inside as extra insurance from a leak developing during tropical depressions or gully-buster rains somewhen. The positive-pressure forced air leak check will catch 98% of current leaks, I'm talking a hour, day or year or two down the road.

Go take a long look at how many rib and brace pieces cross or completely conceal the seams & rivet lines. Maybe time to invent a nozzle for a thin-bodied resin or sealer (HSX?) to fill those spaces with a high pressure applicator, so it extrudes a thin ribbon two inches wide in free air but would nest against the rib/shell and positively inject airgaps with a sealer/adhesive.

Even at 80% success it would go a long way to making each cavity section a better vapor-tight compartment - since we can't pull the external shell and relay it over a dinosaur killer double-sided tape.

One thing the foam-board and spray-can foam can do well is make baffles to reduce the chimney effect of convecting or recirculating air.

Structure the layup with horizontal baffles similar to fire stops in a framed building wall to keep sun heating on the wall from rolling up to the roof or propane heat trapped against the roof from getting the surface areas of the walls to escape from. If the rib cavity has air-gaps open from floor to roof then heat and cold will be waltzing between the extremes 24/7 and radiating in/out energy better conserved in a smaller zone.
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Old 01-07-2013, 07:09 PM   #173
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Leaning towards the-foam-that-must-not-be-named myself, not the whole shell cavity but just the ceiling/roof where the angle gets within 45 of horizontal. I'll be treating the bare aluminum, then glazing everything by adding layers of bonding paint with insulation beads in it, then doing the insulation.
So would you install this yourself with something like Tiger foam or have somebody do it for you? The two part urethane is way better than the spray can stuff.
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Old 01-08-2013, 07:40 PM   #174
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Nope, this is not the place to discuss insulation, nuh-uh, not. (sorry)

Most likely candidate is the anti-microbial Sprayfoamdirect product.

Yet - I'm researching foam aging "Thermal Drift" at the moment.

Dow 'Froth' literature being up front with their drift specifications made me blink... A decrease of 21% R-value per inch (ft2hF/Btu) aging 90 days at 140F!

Applied that loss to Sprayfoamdirect's product R-6.7 means a drop to 5.3 with R-8 total for the full 1-1/2" cavity.... which brings it back down to earth and comparable to XPS, except the speed of installation, moisture barrier and complete space filling advantages. The drift is inherent to all two-part foams. Polyisocyan foam eventually will reduce to Styrofoam values of R4.8-R5.3 per inch as the foaming gas agent gets replaced with air.

Extruded polystyrene (NOT expanded) is said to be R-value labeled at the aged value so I know what I will be using on the walls.

Note there are cold weather formulations for the foams so the foaming gas will not condense out leaving only air at arctic low temperatures! The best will actually gain R-2 in value going from 20C to -20C, R-6 to R-8~. How we can compare products and get that HFC-134a foaming agent I have no clue.

To dress out the wall foam board it looks like air-cure canned foam: Dow Enerfoam Adhesive PRO FOAM (R-5.2 initial) is sold in 24 and 30 ounce cans ($10, $13 amazon) and uses a reusable spray gun (get the semi-metallic '14' one?) that has near infinite control for accurate delivery, unlike the 'straw' nozzle big-box stores varieties. I think it would be neat to use the thin ribbons of adhesive foam to tack up foam blocks or even a layer of Prodex with plenty of baffle lines then the foam board.... or even a layer of spray foam over the air-gap/prodex..

The two-part foam cures from the inside out so it will do large voids, the air-dry one-part foams cures from the outside in so its limited to an inch thickness at a time.
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Old 01-09-2013, 10:00 PM   #175
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Maybe just a few more insulation posts:)

Wabbiteer, you have a great gift for changing my mind about stuff. I had to go and look at that aging information and it looks like you may be right about polyisocyanurate. The extruded polystyrene does look promising too. I know that southwestern summers are going to cook the crap out of that stuff so anything that can outgas, will and if that lowers the R factor that much, it could suck! This kind of info is greatly appreciated until the day that I buy the stuff and after that I don't want to hear it, OK!!
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Old 01-10-2013, 10:01 AM   #176
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This kind of info is greatly appreciated until the day that I buy the stuff and after that I don't want to hear it, OK!!
Yes'm, I am with you on that!! <let us please ignore the hooting and thrown popcorn falling from the balcony>

Your mentioning urethane foams got me spinning my wheels again.

Reading one online installers description puts the kal in kaleidoscope for my quaint DIY study. "When first installed, spray polyurethane foam's R-value is about 10 for a one-inch thickness. Over time, the R-value drops to about 6.5 (per inch) and stabilizes at that value."

Okay, so that outfit is a mere 5 hour drive away so I've found three installers of urethane foams within 20 miles of Twin Cities. I sure want to appear in one of their equipment lots with the trailer shell on a slow Friday afternoon and have them shoot an inch in just to test their equipment!

One little problem is the poison gases and such an interior fire would produce from any foam products. "Spray polyurethane Foam is to be separated from the interior of the building by a fifteen minute thermal barrier or other approved covering." I don't imagine .032" aluminum sheet to be an approved covering - which leads to a question, would the genius coyote put a layer of paint-on barrier on the exterior metal bonding primer to protect the interior spray foam against a nearby grass/vehicle fire?

I can see where an interior ignition or thermal barrier coating for spray polyurethane foam insulation would be an huge asset - trimming overfilled foam to make the liner sheet mount cleanly would bust up the 'glazed' surface of the foam leaving squatrillions of Nooks 'n' Crannies that a laytex based paint would reglaze and reduce surface area for moisture and odor trapping problems. I look at the '73 trailer outside and can not guess how many pound of fried foods were cooked up in it.

Anyhow - errands and chores are bleating at me. To be continued
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Old 01-10-2013, 05:17 PM   #177
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This camper won't be getting skimpy with insulation, MN cold has turned lethal with a wrong turn on someones own driveway in snow, it sure has me fixated on warmth. I've seen the heat in Arkansas go from 115 and maximum humidity midday out in the fields and not lift to cool off below 90 until 2AM... and it felt good!

Back to the urethane foam - complicated application requiring heated hoses to dispense; could it be the metal warping hot spray folks warn about? I think plan on a 1/4" to 1/2" flash coat allowed to cure so the thermal shock may be more easily absorbed by the shell structure?

And keeping the glazed foam surface on the liner-sheet side untouched, not being greedy then grinding it away willy-nilly might be a worthy plan so only specify in contract an inch thick layer or less and later on filling in the air gap with reflective prodex or extruded polystyrene would make a good hybrid insulation package, and make it easy to fit wiring as needed later on.

I'll be visiting the local foam installers in the next couple of days - be interesting to hear what they have to say especially money wise with all prep work and masking done by myself and delivering the trailer to the work site of their choice...

The super deluxe mail-order double DIY package will run at $1400-plus, half that and finishing with prodex or sheathing may run $1000-plus. I'll pop out tonight in the rain (imagine soft water in Minnesota in January!) and get some measurements for square footage required on my 27' Overlander.
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Old 01-25-2013, 09:58 AM   #178
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This camper won't be getting skimpy with insulation, MN cold has turned lethal with a wrong turn on someones own driveway in snow, it sure has me fixated on warmth. I've seen the heat in Arkansas go from 115 and maximum humidity midday out in the fields and not lift to cool off below 90 until 2AM... and it felt good!

Back to the urethane foam - complicated application requiring heated hoses to dispense; could it be the metal warping hot spray folks warn about? I think plan on a 1/4" to 1/2" flash coat allowed to cure so the thermal shock may be more easily absorbed by the shell structure?

And keeping the glazed foam surface on the liner-sheet side untouched, not being greedy then grinding it away willy-nilly might be a worthy plan so only specify in contract an inch thick layer or less and later on filling in the air gap with reflective prodex or extruded polystyrene would make a good hybrid insulation package, and make it easy to fit wiring as needed later on.

I'll be visiting the local foam installers in the next couple of days - be interesting to hear what they have to say especially money wise with all prep work and masking done by myself and delivering the trailer to the work site of their choice...

The super deluxe mail-order double DIY package will run at $1400-plus, half that and finishing with prodex or sheathing may run $1000-plus. I'll pop out tonight in the rain (imagine soft water in Minnesota in January!) and get some measurements for square footage required on my 27' Overlander.
So we're you able to get a quote on spray foam? We've had deep snow and ice storms around here so not a lot getting done.
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Old 02-09-2013, 10:18 PM   #179
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shopping!

I did some shopping today. I ordered two of the aluminum vent caps from this store in Florida. They are described in detail in this thread: http://www.airforums.com/forums/f455...cap-60573.html One will go on the plumbing vent stack and the other will be for the composting toilet vent.
I also bought new LED stop/tail/turn/reverse, clearance and marker lights. The tail lights look pretty cool and at only $29.95, seem like a good deal Hybrid Series LED Round Red Stop Tail Rear Turn and Back-Up Light - Raney's Truck Parts

I am trying to figure out all the exterior penetrations now before I start putting in insulation. I'm still thinking about an active vent for the bathroom
either a fantastic fan or some other kind of vent system. I wish there was a fan that would increase headroom instead of decrease it.
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Old 02-23-2013, 08:39 PM   #180
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Still looking for a simple solution to a thermal break between the ribs and interior skin...
I found an interesting article dealing with thermal breaks in steel framing construction. http://www.homeenergy.org/show/article/id/249

The basic idea is that you can reduce the contact area between the steel stud and the interior surface of the wall by dimpling, cutting out some of the material, or changing the geometry in some way.
I think the the dimpling idea may be the easiest one to carry out. If you took something like a bucking bar with a 1 mm high small bump on it, you could hit the outside of the rib with a rivet gun with a rounded head and make a small bump on the rib wherever you wanted. It seems that enough of these along the ribs could result in a significant decrease in the contact area between the ribs and the inner skin. A 1 mm air gap would do wonders.
Any thoughts...
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Old 02-28-2013, 09:28 AM   #181
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Point: Since aluminum is such a great thermal conductor even a ribbon of thin gasket paper would stagger heat gain/loss.

Aluminum is soft enough - and aluminum oxide gnarly enough - that simple metal-to-metal texture will quickly erode from vibration and heave & shrink.

As a parallel example think liner rivet 'black ring' from fasteners loosing their stretch so the metal shows slipping, the aluminum oxide black dust just keeps regenerating itself while the metal wears away.

Reducing the liner metal contact area is a good idea but there needs to be friction/binding area all along the original contact radius, having a .010 non-compressible shim under rivet attach points and your choice of insulation under the remaining areas might be ideal but a real PITA to pull off unless the liners are pre-drilled to flag where the shims need to be.

The rivet bores will still drift meandering the radius with shims - but anything, even paint will try and cause the bores to keyhole, the effect may be to ripple the liners as they seat, or expand when they heat up.

One odd thing occurred to me - pallet banding strap as a constant thermal break - stand off - incompressible and weather-proof - cheap - available - may be a decent compromise.

The lowest quality strap is polypropylene, it creeps with temperature changes but won't shatter under extreme cold, then polyester and nylon with nylon being the most inert and strongest but can turn glassy under extreme cold and might spiderweb crack around the rivets.

On a wild hunch I looked up a few details on thermal conduction:

304 Stainless: 16.2 W/m-K (112.4 BTU-in/hr-ft-F)
6061-T6: 167 W/m-K (1160 BTU-in/hr-ft-F)

Even running eBay 304 SS pallet banding tape ($250/400') as the thermal break would reduce heat xfr by ~90%. So don't get too obsessive, anything gnarly will do - I'm doing paint as the thermal break.
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Old 02-28-2013, 11:38 AM   #182
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That thin white foam material that is commonly used for packing stuff would make a good thermal barrier. The problem with aluminum is that it has such high thermal conductivity that even if it touches in a few places it is still going to conduct heat well. I would use twice the number of pop rivets since the rivets will be able to float more with a barrier between. You could use just about any plastic sheet material between the skins and the ribs. You can get rolls of Mylar etc. You could glue it to the ribs. You going to use the old skins or make new ones?

Perry
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