My Homemade English Wheel

What started as a joke has become an indispensable piece of equipment.

I had been stalled for months with completing the belly pan, which meant I also could not attach the lower interior skins, since the C Channel on the floor/deck must be exposed in order to buck rivet the belly wraps to the Airstream properly (buck riveting requires access to both sides of the thing being riveted).

The original banana wraps (the curved pieces that go at all four corners of the belly) were extremely beat up.  I had a lot of trouble finding new ones, as I didn’t want to use the black plastic ABS banana wraps that are now being utilized on new-build Airstreams.

I made several attempts at smoothing out the original banana wraps with rollers, sandbags and hammers, etc., but nothing was making them look like they needed to.  I started researching English wheels to shape sheet metal, but they are incredibly expensive.

The aluminum banana wraps are quite soft (which is a huge part of why they are so banged up), so I knew I didn’t need a “proper” English wheel used to shape and form steel.  Thus, I started thinking about what I had lying around that might work in a similar way.

I have these huge, ancient casters that came from my grandfather’s farm.  I always thought they’d end up going on an industrial style coffee table or cart, but I realized they would be great for flattening aluminum.  As a bonus, they are made from really hard rubber, so they don’t cause creases or dents at the edge of the wheels like hard metal might.  I had an extra vice laying around, so I cobbled together this contraption:

It worked!  And while it wasn’t perfect, I was able to get the job done.

For this job, I placed the weights in the following picture over the wheels to get the pressure I needed, but a second vice on the opposite side of the current one will obviously be a more elegant solution.

 

Insulating an Airstream (part 2: practical application)

After weighing all my options (see part 1), I decided to go with Polyisocyanurate rigid panels for insulating the Airstream.  Both Lowe’s and Home Depot carry PIC, but I like the Home Depot brand better (Rmax, made in the USA).  The PIC panels are far superior to styrofoam and extruded polystyrene in just about every way (except price, but they’re actually only a few dollars more per sheet).  PIC is certainly more fire-retardant (though not fire proof), and definitely equally if not more moisture resistant.  They don’t call it moisture proof, but I assume that is for legal reasons only.

I actually did a test where I fully submerged pieces of PIC in sealed jars full of water and let them sit for extended periods of time.  After three days submerged, the PIC came out weighing exactly the same as when it went in (indicating that it took on little to no moisture, or it would have been heavier).

After two weeks the PIC did weigh a bit more when I first removed it from the water, but after letting it sit for around an hour, it returned to its original weight.  I did another check at 6 months and got the same results.  Maybe not the most scientific test in the world, but good enough for me.

I went a little crazy with the actual application of the PIC panels.  I decided the best method is to first cut the 1/2″ thick PIC panels into small pieces and then glue them with TremPro 635 to the exterior skins.  I tried a bunch of different stuff for adhesive (TremPro 635, Vulkem 116, Silicone, 3M VHF tape, etc.), but I think the TremPro 635 is best.  It works whether you’re applying it in hot/cold weather, and it’s definitely going to last.

At first I was cutting the 1/2″ thick PIC into tiny 1.5″x1.5″ pieces (see photos in gallery below), but that was taking too long, so I started using 1.5″ strips (at whatever length was good for the location).  I then cut sections from 1″ thick PIC panels to fit between ribs and cross members.  This leaves an air gap against the skin for airflow and moisture runoff (and the possibility of running more wire if I ever need to).  This method also makes it easier to repair damaged exterior panels if that dreaded moment ever arrives (vs. spray foam, which is crazy-hard to remove when repairing the exterior skins).

In places where there is a curve in the wall, you need to score the PIC to allow it to conform to the curve.  After I scored my PIC panels, I resealed the cuts with foil tape.  This is pretty easy where it’s just the simple curve of the upper side walls, but it gets tricky for the compound curves of both end caps.

Finally, I sealed everything up against the ribs and cross members and window frames with Nashua 324A Foil HVAC tape (see photos in gallery below).  Nashua 324a foil tape is my best friend.  Be careful though, it will slice you if you run your finger down the edge!

 

I purchased two 3″ wide rolls at Goodwill for $10 about a decade ago.  When I ran out of that, I was worried because all I was finding online was a 60yd. roll for around $40, but luckily after checking the big box stores I found it at Home Depot for $17/roll (60yds., 2.5 inches wide).  It’s rated to hold from -25F to 325F.  That wouldn’t work if it were applied directly to the exterior skins (they actually get hotter than that in the sun), but it’s fine for using to seal the interior of the PIC panels.  It sticks in the extreme cold, and it sticks REALLY well (even during application, which works all the way down to -10F).  I’ve got a roll of some other non-marked foil tape (thought the cardboard roll does say Nashua), but it may as well have NO adhesive whatsoever compared to the 324a.

I also decided it was a worthwhile endeavor to put a thermal barrier between the ribs and the interior skins.  The interior skins are aluminum like the exterior.  The ribs are also aluminum.  That means when the sun is baking the exterior of the Airstream, all that exterior heat is transferred via the ribs to the interior skins and basically turns your Airstream into a toaster oven.  I have NO IDEA why Airstream doesn’t utilize a thermal barrier on the ribs from the factory.  I did some research on materials (using EPDM rubber, rolled polysterene, etc. –I even researched aerogel) and found that the best bang-for-the-buck solution is the blue polystyrene you use when laying framing on a foundation.  It’s only $6 a roll at the big box stores, but I often find new rolls at salvage places for $2.  It’s light, it’s thin, rivets obviously go through very easily, and it makes a HUGE difference to the interior temperature.  I used an infrared temp. gun to take some readings of the interior skin over the ribs with and without the polystyrene barrier, and on an 80 degree, sunny, Colorado day, there was up to a 120F difference!

Regarding the idea of a moisture barrier… The PIC is foil faced on both sides and then sealed with foil tape on the interior.  I think that is plenty for the “exterior” moisture barrier, not to mention the gap between the exterior skin and PIC panels for moisture to shed.  Regarding the idea of this causing too much moisture to be trapped inside the Airstream (especially when using the propane appliances and heat)… I guess time will tell how bad it could get.  One can always open vents/windows, so we’ll see how it goes.  Luckily I’m not too worried about moisture collecting in/on the PIC panels, after doing my fully-submerged panel tests.

Finally, I am using two 2″ layers of PIC with air gaps between the panels and at the decking for insulating the belly. In addition to acting as a thermal gap, the air gap between the underside of the decking (floor) and the first layer of PIC also helps eliminate floor rot from moisture collection.

Removing the Old Air Conditioner

Every time I looked at the Airstream, I wanted to immediately take the old, rusty a/c off.  I resisted doing it last fall (so there wasn’t a gaping hole all winter), but even though it’s now Spring and raining quite a bit, I just couldn’t hold myself back any longer.

Someone installed the a/c that was up there with about a million tiny screws (vs. rivets)  and a WHOLE lot of goo.  The installation included two aluminum “L” rails running the length of the a/c unit.  I’m not sure what they were for (condensation?), but to me they were just more garbage to remove.  I waited till the hottest part of the day and peeled back as much goo from where I could tell the screws were, and then unscrewed as many as I could.  I think I got pretty lucky, ’cause there were only about 4 that didn’t back out.  Those four I grabbed with a vice grip from below to turn, and once they were backed out enough, I grabbed them from above.

I probably should have waited and gotten some help from a friend to bring the a/c down, but I was on a rampage, so I just laid some old sleeping bags on the Airstream skin to avoid scratching anything, and then slid the unit over and down the rails of my ladder.  That thing was heavy.  I texted my dad a pic to show him how strong I am.

So what was left was a gaping hole and a lot of nasty goo (from the looks of it, silicone, latex, vulkem, and butyl tape).  I waited till the hottest part of the next day and scraped as much off as I could with a dull chisel (to avoid scratches).  Then I used Goof Off, a scotch brite sponge, a rough rag, and a brass wire brush on the end of my drill to remove a sufficient amount of what was left.  I didn’t go to town getting it spic ‘n’ span because I still don’t know what I’m going to do up there to finish things off (bubble sky light?  gunner’s touret?  sunbathing deck?), so I’ll wait until then to make things pretty.

Once the skin was cleaned up, E and I buck riveted all the screw holes closed.  I put a dab of TremPro 635 on each hole before setting the rivet, so I’m pretty confident that everything is water tight.

There were a couple screw holes that were actually “double drilled” (two holes right on top of each other, but simply putting two rivets right on top of each other seemed to do the trick (luckily you can’t really see this stuff from the ground).

Now I just have to decide what to do with the hole that’s left.  There’s a tiny chance that I’ll put a new, smaller a/c back on the roof, but I really like the clean look not having the a/c on the roof, and I’m considering installing a split on the tongue.  For camping this summer (in our friend’s yards), I’m actually just going to put a window unit in the access opening where the water heater used to be.

airstream-a-c-01

Temporary A/C Set Up

Oddly enough, the highly rated, *almost* EnergyStar (missed the mark by .1 points –so essentially EnergyStar rated without the upcharge) window unit I found is EXACTLY the same size as the hole that already existed for the old water heater.  How lucky is that?  I will be making a sliding system from heavy duty computer-rack sliding rails so the unit can simply slide out when we reach our destination, and then back in when we’re ready to go!  I’m not sure yet if this will be just an auxiliary unit to cool the bedroom and complement a “whole trailer” unit or if it will work (in tandem with some fans and perhaps even some ducting) to cool the whole Airstream.

TremPro 635

All Kinds of Goo (Poly Caulk and Other Seam and Leak Sealers)

There are SO MANY different kinds of stuff to use for sealing seems and leaks in an Airstream.  The Original stuff used in manufacturing was called Vulkem 116, and it’s still available (either as Vulkem 116 or TremPro 626), but the original Vulkem company was bought out by TremPro.  Vulkem 116 is gritty and will stick to EVERYTHING.  It also takes FOREVER to cure (so cleanup rags will remain gooey for days).

There are a LOT of varying opinions about what’s best to use for what, so I am posting what I’ve learned from researching and using the various products.

The original factory “caulk” is Vulkem 116 (gray), and is now marketed as either Vulkem 116 (the original name) or TremPro 626.  It’s a texturized (gritty, like it contains sand) poly that takes FOREVER to cure (which can be a good thing when you’re talking Airstream).  The “official” cure rate is 48-72 hours, but it can take a lot longer than that, depending on the actual environmental conditions.  Vulkem 116 also cures fairly hard when completely cured, and is thus best for exterior panel seals, a/c installation, setting window frames, etc.

Vulkem 631 is Vulkem 116 but in different colors.

TrempPro 636 (gray) has a slow cure rate (4 hours), has more solvent (better for exterior applications), and is non-textured (smooth).

TremPro 635 (gray) has a faster cure time (90 minutes), and is a low VOC/solvent free silane terminate poly.  So far, this stuff is my favorite, especially for things on the inside.  If you’re doing Airstream restoration, I recommend having at least two tubes of this stuff around, as it’s not available from a lot of places and often takes a while to ship and arrive.

Sikaflex 221  (black) has a fast cure time (60 min.), but seems to require a cleaner surface for adhesions, whereas the Vulkem and TremPro will stick to just about anything.  Some people think it looks better (smoother, more like typical caulk) and is a little easier to work with (doesn’t stick to everything).  It’s typically used for things like interior vent, window, latch, etc., applications.

The products above are for more “construction” type applications.  There are several products like that can be used to seal tiny cracks and leaks around rivets, etc.  These sealers actually wick into the cracks and crevices, whereas the products above are more for adhesion and filling larger gaps and holes.

Acryl-R seems to be a lot of people’s favorite for a wicking sealant, but it takes a special applicator.  The “go to” product for sealing on the road seems to be Captain Tolley’s Creeping Crack Cure.

Parbond from Parr is a sort of “in between” product that comes in a “roll-up” tube (like toothpaste) instead of a caulking tube. It is silver, so shows less than something like Sikaflex on exterior applications.  This is a good product to have with you on the road when you don’t want to store a caulking gun and larger amounts of sealant.

Butyl Putty Tape is what you need to use when setting windows, a/c, vents, and other things that have a collar and set in to a hole in your Airstream exterior.  This soft, flexible product is like a roll of flat Silly-Puddy that will seal two surfaces together and keep them that way.

Walbernizer specifically formulated for Airstream coated aluminum surface.

 

BAL Stabilizer Jacks for Leveling Airstream

When you park your Airstream, it’s rarely on perfectly level ground.  Chocks and blocks of wood or rubber under and around the wheels can help even things out and keep the trailer from moving, but stabilizer jacks are best for keeping your home on wheels from wobbling all over the place while you walk around inside.

The Airstream part number for the original jacks is 400093-A, and the manufacturer’s number for the replacements (which are pretty much identical) is 20-8-T.

You can weld the jacks to the frame, but it’s much easier (and equally effective) to simply bolt each jack to the frame of the Airstream (be sure to bolt to the appropriate cross members).  I used self-threading bolts and drove them directly through each jack’s 1/4″ holes and into the Airstream frame.  The bolts are really only holding the jacks to the frame; once opened, the jacks stay in place because the weight of the trailer is bearing down upon them (gravity!).

You will want to be sure you are getting jacks with the extended operating arm, as it protrudes farther to the edge of the trailer than the “normal” operating arm.  If you have the shorter arm, you will have to crawl under your Airstream every time you need to extend the jack.  The operating arm is turned by a crank, but I plan on keeping a socket in my Airstream toolkit so I can operate the jack with my drill (manual cranking is for chumps).

installing stabilizers

installing stabilizers (they are on blocks because the entire Airstream is currently lifted for working on the tanks and bellypan)

20151208_110345

I have heard many tales of people forgetting to crank up their jacks when they leave a site.  As you can imagine, this could cause some pretty serious damage to your trailer’s underside, not to mention destruction of the jacks themselves.

Also, NEVER use your jacks to lift the trailer.  They are rated for 2,000#’s (static load) each, but they are NOT meant to lift your Airstream off the ground.

Manual:
Deluxe BAL “T” Type Stabilizing Jack (20-8-T) mounting and operation manual via Norco Industries
http://norcoind.com/bal/downloads/manuals/T-Type%20Stabilizing%20Jack%20%2820-8-T%29.pdf

Purchasing options:
http://www.vintagetrailersupply.com/BAL_Deluxe_Stabilizing_Jack_p/vts-739.htm

http://odmrv.com/catalog/index.php?main_page=product_info&products_id=369

Discussion:
http://www.airforums.com/forums/f43/bal-stabilizer-jacks-7640.html

Rivets!

If you’re going to work on an Airstream, you have to know about rivets.  Here is some basic information to get you started.

You “pull” a blind rivet.  You “buck” a solid rivet.

First of all, there really shouldn’t be any screws on an Airstream.  Screws will back out of their holes with the constant road vibration that an Airstream experiences, so eventually a screw will no longer be holding whatever it was screwed into.  Rivets are more “permanent” in that they stay put.  But don’t worry, they are easy to drill out if you need to change something you’ve riveted.

Blind Rivets

There are two types of rivets on an Airstream: bucked rivets and blind rivets.  Airstreams use only two sizes:  1/8″ and 5/32.”  The 1/8″ rivets are generally used for trim on the exterior, and to hold the skins to the ribs on the interior.  The 5/32″ rivets actually hold the Airstream together (panels and ribs).

Blind rivets get their name because you can install them in situations where you can’t see both sides of the surface being riveted (there is a blind side).  So if you are fastening something to another surface without being able to see the back (like skins or trim), you would use a blind rivet.

There are two types of blind rivets, often referred to as “Olympic” and “pop” rivets.

blind rivet (olympic rivet)

blind rivet (pop rivet)

The pop rivet is a pin with a bulb head (the mandrel) inserted through a cylindrical shaft.  The rivet is “pulled” with either a manual or pneumatic puller.  The center pin pulls into the shaft which in turn expands and keeps the rivet in place.  The pulling tool cuts the pin at the head once it pulls into the shaft leaving a dimple in the head where the pin has been cut off.

manual rivet puller

manual rivet puller

pneumatic rivet puller

pneumatic rivet puller

You can get a manual rivet puller from Harbor Freight for under $10.  This is pretty nice to have on the road, as you can pull rivets without needing an air compressor.  The pneumatic rivet puller is a bit nicer, especially if you are doing a LOT of rivets, but obviously it requires a compressor, so it isn’t as portable for road repairs.

The Olympic rivet operates on similar principal to the pop rivet, but the containing shaft splits into three arms that hold the rivet from behind the sheet being riveted (like a drywall anchor).  You can machine/shave a blind rivet to make it look like a bucked rivet with a smooth head (see photos below).

Here is a good thread on Airforums containing the photos below regarding how Olympic rivets work (the photos are from user flyfshr).
http://www.airforums.com/forums/f381/olympic-rivet-removal-and-installation-23.html

photo credit: flyfshr on airforums

expanded Olympic rivet

photo credit: flyfshr on airforums

rivet shaving tool

photo credit: flyfshr on airforums

unshaved Olympic rivet

photo credit: flyfshr on airforums

shaved/machined Olympic rivet

For the record, Olympic is actually a brand name, not a type of rivet (like Kleenex is synonymous with tissue).  There are many types of rivets made under the Olympic name. Only one type is originally used on Airstreams. They’re called Olympic Bulb-Tite Shaveable Head rivets, either 1/8″ in size or 5/32″.

Bucked Rivets

buck rivets

buck rivets

Bucked rivets look like tiny metal mushrooms.  There are no moving parts.  A bucked rivet is hammered with a pneumatic riveting gun, and the soft aluminum mushrooms out to hold the rivet in place.  Buck riveting usually takes two people, because someone needs to hammer one side while someone else “backs” the rivet by holding a small anvil (the buck bar) against it.

Advice on rivet length from this thread:

Always try to use the correct length rivet. It should be long enough to penetrate the parts to be riveted and still protrude to a length approximately 1-1/2 times the rivet diameter. In other words, a 1/8″ diameter rivet should stick out about 3/16″ (certainly not less than 1/8″) before it is bucked.

buck riveting gun

buck riveting gun

bucking bar

bucking bar

 

The rivets on my Airstream aren’t all perfect (some are far from it, in fact).  There seem to be a lot of factory rivets that were skipped or at least skimped on.  Below you can see some examples of what I’m talking about.

Before (through the holes, but not really mushroomed and holding anything together):20151206_140752

20151206_140801

After (mushroomed out and actually holding the two pieces of aluminum together):20151206_140811

Clecos

clecos

clecos

I love clecos.  Mostly just because they look cool.  They are like clamps for riveting.  Basically they are temporary rivets.  You place clecos in rivet holes using a special cleco tool (cleco pliers) that makes the spring-loaded cleco grab and release by pushing on the end of it.

cleco pliers

cleco pliers

clecoed in place

vista vue window clecoed in place

Removing Rivets

Rivets are removed by drilling them out.

Sometimes you will see/hear people using a number instead of a size (inches or millimeters) for a drill bit.

5/32″ is .15625 and a #21 is .159; thus the #21 drill bit gives a 5/32″ rivet a little clearance to slide into the hole.

#40 = 3/32”

#30 = 1/8” (which is the shank size of the rivets used most extensively in assembling the interior of an Airstream)

#10 = 3/16”

For removing Olympic rivets, Andy from Inland RV says:

An Olympic rivet is 5/32 which is .15625 inches

 

#20 is .161
#21 is .159
#22 is .157

 

The best drill bit size to use is a #21, since a hole will not be perfectly round, unless using a drill press.

Andy also says:

Olympic rivets for Airstream usage have always been 5/32 shank, but with the same size “brazier head” as the 1/8 buck rivets.

That is so the looks do not basically change and the strength of the shank was maximized, so as to be similair to the buck rivets shan strength.

For what it’s worth, I have just been using 1/8″ and 5/32″ drill bits to remove rivets and to install rivets.  I simply use the bit to route out the head, and when that pops off (sometimes you might want to use a sharp chisel to carefully shave the head if it’s being stubborn), I make sure to be centered and drill out the old rivet body.

Other links used for this post:

Removing a solid rivet: http://wiki.matronics.com/wiki/index.php/Removing_Solid_Rivets

http://www.airforums.com/forums/f381/right-size-drill-bit-for-olympic-rivets-85451.html

http://www.airforums.com/forums/f381/factory-rivet-vs-repair-rivet-6368.html#post49015
post #14 = pics of all the rivets

http://www.airforums.com/forums/f381/buck-rivets-or-olympic-rivets-32693.html

http://www.airforums.com/forums/f381/buck-rivets-look-wrong-using-wrong-air-hammer-bit-120715.html

Insulating an Airstream (part 1: research and theory)

Sprayed Foam vs. Rigid Panel vs. Batt vs. Bubble/Foam Foil

I had quite a few questions to answer before deciding how I would insulate our Airstream.  I was lucky enough to get our trailer with the interior already removed, which means I didn’t have to deal with the toxic mess of removing the original fiberglass batt, which is almost ALWAYS infested with rodents, their homes and tunnels, and their droppings in these older Airstreams.  Not only that, but the batt is usually wet and filled with mold, and often still glued to the skins and difficult to remove completely.

I knew I wouldn’t be reinstalling fiberglass (it’s AWFUL to work with, and doesn’t hold up as well as a lot of the newer alternatives), but I wasn’t certain as to which option would be best for us.  My initial thoughts revolved around using Spray Foam, but I did a lot of research and eventually decided to go a different route.

Here were my areas of concern when thinking about insulation for the Airstream:

  • maximizing R value
  • containing heat while allowing vapor/moisture to escape (we plan on using our Airstream all four seasons)
  • ease of installation
  • cost
  • availability
  • durability and endurance (how long the insulation will last)

Spray Foam

As mentioned, Spray Foam was my initial choice for insulating the Airstream.  The thought of using a very light product that not only gets into EVERY nook and cranny, but also seals things up and ads structural integrity to the trailer just seemed like a no brainer.  However, there were some issues I uncovered that eventually caused me to go in another direction.

Spray Foam Cons (for my Airstream):

  • Harder to find material or someone to do it
  • Commercial sprayers create heat than can warp skins and ribs
  • You have to do it all at once (nozzles are one time use, rented equipment or someone else doing it, etc.)
  • Even though it’s not necessarily toxic (depending on the specific product), it makes a mess
  • Once installed, repairs are very difficult because the foam is bonded to the skin and must be removed with chemicals –this is the main reason Timeless Travel Trailers doesn’t use spray foam in their trailers

A lot of people on the Airstream forums expressed concerns with Spray Foam breaking down into “fine powder” because of road vibration, but I think there are enough examples of places it has been used successfully (factory installed in various Argosy and other brand trailers, most modern refrigerated trucks, people who’ve done it themselves, etc.), to eradicate those concerns.  Perhaps the cheap “canned foam” options from big box stores would break down, but I think commercial products will hold up to the rigors of the road.

Bear in mind, if you go the Spray Foam route, you need to make sure the product is closed-cell foam (not open cell, like the canned stuff at the big box stores, which will take on and retain moisture).

Also, spray foam seams like a bad idea for the chassis (insulating the underside), as it will retain water between the floor and the foam and thus contribute to floor rot, not to mention it prevents access to all the stuff down there that might need regular access (wiring, plumbing, holding tanks, etc.).

Fiberglass Batt or Rockwool

If the state of the original fiberglass or rockwool that you see when removing your panels isn’t enough to assure you that there are now better choices, here are some other reasons fiberglass batt sucks:

  • collects and retains moisture that turns into mold
  • moisture greatly reduces R value
  • is easily penetrated (inviting even) and harbors vermin
  • awful to work with (incredibly itchy in your skin)
  • settles in the walls to reduce R values over time much more so than rigid panels or spray foam

Foil-faced Foam and/or Bubble Wrap

A lot of people go with Reflectix or Prodex. And though the two products look similar, they are actually quite different.  Reflectix is foil-faced bubble wrap (yes, that bubble wrap).  It’s fairly worthless.  Prodex is actually foil faced closed-cell polyethylene foam, which has a greater R value than bubble wrap (meaning a “real” R value).

Reflectix is more readily available; you can pick it up at your local big box store, but it doesn’t do much for you.  Your Airstream is already made of a reflective material (shiny aluminum!), and the bubble wrap doesn’t really insulate anything (very minimal air contained within the thin layer of “bubble”).

Prodex must be ordered, it’s relatively expensive, and I’ve read in quite a few places about Prodex delaminating (the layers coming apart). 700 square ft. (two, 24 inch wide x 175 ft. rolls) is around $250.  Most variations on size still come in around $250 for 700 sq. ft., so the product is around $2.80/sq. ft. (right around the same price as Rigid PIC Panels).

Many people will point out Prodex’s claim of an R-16 rating, but that rating comes with some pretty unattainable parameters (at least in an Airstream).  From their product spec sheet:

Parameters of test: 24-inch on center 2″ x 6″ wood assembly. Roof application. Test method ASTM 1116. Airspace of 2.64 inch on each side of product. Heat-flow direction down. Interior side of product exposed.

To get an R-16 rating from a 3/16″ sheet of Prodex, you need more than two-and-a-half inches of air space on either side of the material, PLUS air flow (venting).  I can’t seem to find an R value for the product without the air space on either side.

Prodex is extremely easy to install and they claim it is self-sealing, so that’s great, but cost and availability (and the fact that the Airstream doesn’t have 5 inch walls) knocked it out of the running for me.

Polyisocyanurate Rigid Panels

There are several types of “rigid panel” foam products.

Polyisocyanurate (PIC) panels are rigid foam panels that are quite water resistant and sport an R value of 6.5 per one inch of thickness.

Thermasheath Rmax is sold in 4’x8′ sheets and is readily available at Home Depot (Lowe’s does not carry any PIC panels, only extruded poly and Styrofoam).  At the time of this posting, here in Colorado a 1/2″ thick panel (R 3.2) is $11.97, a 1″ thick panel (R 6.5) is $16.35, and a 2″ thick (R 13.1) panel is $28.85.  Obviously the 2″ thick product is too thick for the Airstream wall cavity, so you’ll either need to go with the 1″ thick product or multiple layers of the 1/2″.

The 1″ thick panels will need to be scored to follow the contour of the Airstream walls, and the scores then need to be resealed with foil tape to maintain the moisture/radiant barrier of the foil facing.  The 1/2″ panels will actually bend enough to follow the contour of an Airstream (though not the compound curves of the end caps) without scoring the backside of the panel.  If cost is not an issue (the half inch panels are more expensive in regard to total volume), multiple layers of 1/2″ panels are easiest to install since they don’t need to be scored.  And in the grand scheme of things, the extra $8 per 1 inch thickness in a 4’x8′ panel is probably well-worth the extra cost in saved time and the fact that there are no voids from scoring and bending like the ones that will be created in the 1″ panels.

An added advantage of both rigid panels and foil faced flexible foam is you can run wires in the voids.

Other

FWIW, I’ve not heard of anyone using “blown-in” cellulose or recycled denim, but I would think potential moisture penetration would make that a bad choice, as well as major settling of the material from the motion and vibration of the trailer.

Thermal Bridge

Finally, something to consider is the thermal bridge… anywhere things “touch” from outside to inside will conduct heat/cold.  Insulation can help mitigate this effect between exterior skin and interior skin, but the major problem area is the ribs, which touch both the exterior skin and interior skin, and are made from highly conductive aluminum!

I tried looking in to Aerogel/Thermagel for the Thermal Bridge.  Specifically I e-mailed, called, and even snail-mailed Aspen Aerogels in Massachusetts, but I never received a response.  I assume this is because I’m “small beans,” and they deal with only multi-million dollar outfits.  Considering they seem to be marketing mostly to the oil industry, I am almost certain that Aerogel is cost prohibitive.  I have a cousin in green tech and solar who let me know that Aerogel in it’s original form is pretty hard to work with.  It was described to me as tapioca-like goo inside a thin wrapper.  I would think punching a bunch of rivets through a bag full of pudding wouldn’t work so well.

I have wondered about using neoprene, some left over EPDM rubber I have from the roof on my studio, or even just the blue role of closed-cell poly material that you use between a house’s framing sill plate and the concrete foundation when building a house (i.e. something like Dow Weathermate Polystyrene which is readily available at Lowe’s/Home Depot).  I’m not sure if such a thin layer of material would really help prevent heat transfer at the ribs.  And even though it’s thin, I’m wondering if it would be a problem (an extra layer of material) between the ribs and skin.

On to part 2: practical application (what I actually did)…

Exterior Running Lights

Our Airstream came to us with the exterior running lights already wired (a mixed blessing: they don’t look as cool as I’d like, but I didn’t have to do anything with the lights to drive it home).  Some (not all) of the lights had been replaced with LED, but the housing on those new LED lights doesn’t have a gasket at the base; rather, it looks like it’s missing a gasket around the base of the light.

Evidently this is how they are supposed to look, but I wish it looked a little more integrated.  I’m going to leave them as-is for now (they work and they don’t let water in), but maybe someday I’ll make them a little more “fancy.”

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Removing and Re-installing a VistaVue Window

Today I removed, cleaned, and reinstalled a VistaVue Window.  Someone had tried to “repair” the leaks in the window with about a gallon of silicon (only a slight exaggeration).  Don’t EVER use silicon to “fix” leaks on an Airstream.  It looks awful and is impossible to remove if you need to redo the seal.  The only place you should use silicone is to adhere weather stripping gasket (around doors, windows, and hatches) and where glass is in direct contact with something (meaning, a window gasket).  Instead of using silicone, use a polyurethane caulk.  I really like TremPro 635.  Parabond comes in a container that’s more like a toothpaste tube, so it might be easier to take with you for mobile repairs.

removing rivets (check out that crazy silicone mess!)

removing rivets (check out that crazy silicone mess!)

I drilled out all the bucked rivets, removed the tons and tons of silicon and other adhesives from the resulting hole in the Airstream as well as the window bracket (the aluminum around the glass), then I went the extra step and removed the bracket from the glass and cleaned the gasket that was in between the glass and aluminum frame.  Getting the frame off of the glass can be tricky.  There are actually metal pins in each channel where the two pieces of the frame come together in the center.

the metal pins holding the two pieces of frame together

See the metal pins holding the two pieces of frame together?

you can see the pins a little better here

you can see the pins a little better here

The bottom pins had rusted away completely from water sitting inside the window frame, but the top pins were still there (and very strong).  I ended up prying the two frame pieces apart slightly with a chisel, then I cut the two pins with a Dremel cut-off wheel.

another close up of the frame pins

another close up of the frame pins

These pins will slide in their respective channels (though it’s hard to move them), so I ended up leaving them in place, then pushed them back over to function as they original did once I put the two pieces of aluminum frame back together.  One half of each pin will still work even though they are shorter now from being cut.  I thought about trying to get the second half of each pin out to use on the other side, but they are in there REALLY tightly and the small channels for the pins in the other side were too badly corroded to accommodate the pins anyway.

I used a brass wire brush (gentler than steel so it doesn’t deep-scratch and ruin the soft aluminum) to clean the big stuff off of the aluminum surfaces of the Airstream body and window frame, then mineral spirits and a rough rag to remove the smaller left over gunk.   I used a razor blade to carefully remove silicone from the surface of the glass, then went over the glass with mineral spirits and a rough rag.  I also found that if I was gentle I could use super fine (0000) steel wool to help get off the really tenacious stuff without scratching the glass.

cleaning off more silicone

cleaning off more silicone

I washed the gasket with warm, soapy water.

washing the gasket

washing the gasket

The gasket had hardened a bit on the lower side (where water and minerals had sat in the frame), but there was only one small split in the actual material, so I decided to reuse the gasket instead of ordering more and having to wait for it to arrive (VTS: 70’s Window Gasket).  This also meant the gasket would be a single, continuous piece and already sized for the window so I didn’t need to worry about over stretching the gasket material.

I have read on other blogs that people have forgone the gasket and just set the glass inside the frame after applying liberal amounts of silicone, but I like that I don’t have to  worry about the glass touching the metal frame, and the gasket gives it a firmer hold (it is tight in the frame channel).

After washing the gasket thoroughly and cleaning out the window frame channel with a brass wire brush and mineral spirits, I squeezed clear 3M Marine Silicone (purchased at the local big box store) into the gasket and slipped the gasket over the edge of the window glass.  I then squeezed a liberal amount of the clear silicone into the two pieces of window frame and slid the two pieces of the aluminum frame over the glass and gasket.

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You need to clamp the frame onto the glass while it dries.  I used a ratched strap for the long axis, and cheap Harbor Freight grip clamps for the shorter axis.

clamping while the silicone dries (note: don't clamp the center too tight!!)

clamping while the silicone dries (note: don’t clamp the center too tight!!)

Unfortunately, I made the mistake of clamping the center of the frame too tight and ended up with a slightly “bow tie” shaped window frame; the added bonus here was that the center holes no longer lined up to the skin for riveting.  What this means is that the corners of the frame are not snug against the glass, thus you shouldn’t try to make the center of the frame snug against the glass or you will end up with the bow tie like I did.

I solved the problem by using a clamp (reversed) to stretch out the center of the frame and am just crossing my fingers that the seal holds up (I re-siliconed the gaps where the gasket pulled away from the frame, but I’m hoping there was enough silicone in the channel that it wouldn’t have leaked anyway).

Butyl tape (that stuff is GREAT) was placed around the perimeter of the window frame before riveting the window back in place.  I am leaving the butyl tape “squished out” for a while so it can shrink and expand in the sun, then I’ll trim it with a utility knife.

showing the butyl tape

showing the butyl tape

Hopefully the leaks are now banished forever!  See the complete photo gallery from the job below.

Others Who’ve Done It (Airstream Restovations)

Here are some links to other Airstream renovators who’s posts I’ve found helpful.  There’s no way I could do what I’m doing without these people having posted their experiences (and advice).  I’ll try to keep adding to this list as I find and use more and more threads/blog.: