Foil Bubble Insulation Methods

[steve O]

Spray Foam sounds great but.... what if you develop a leak....will that foam soak
up the water? Then how do you get it out???? If i was to use spary foam on a vehicle
of any kind i would use the closed cell type (One advantage with the FG batts they
will dry out and can be re used). If one wants a superinsulated travel trailer i think
one would have to re think the basic Airstream design and start from fresh. Its a great unit but not built to heat efficiently in really cold weather. Living in Michigan its easy to pump the propane in and/or run a little electric heat.
Couple of years ago I cranked up the heat inside my trailer, had the temps up to
60 along the top middle. Skins were 60 and the rivits were 40! The outside temps were in the mid 20's. Thats a big loss of heat. Temps were take with an ir thermometer. I have a 72 safari and love it!

[j54mark]

Originally Posted by steve O

If one wants a superinsulated travel trailer i think one would have to re think the basic Airstream design and start from fresh.

Avions, at least the last years anyway, had foam insulation sandwiched between the inner and outer panels. However, with the aluminum framing connecting the two they apparently suffered from the same heat loss/gain as Airstream.

It is difficult to imagine a superinsulated trailer that would yet retain its character as a recreational vehicle. However, I'm not at all sure a complete rethink would be required to acheive a significant improvement. A simple thermal break would be of immense value. This could be done with that blue closed cell foam that is sold at home centers in 4X8 panels. Putting an 1/8th, or even better, a 1/4 inch thickness up on the ribs before adding the interior panels would have, I believe, a dramatic effect at a negligable loss of interior room. At that point the only point of high conductivity would be the rivets themselves.

Before anyone asks the factory to do this for them, it would require thicker door and window frames, so much retooling would be required.

Mark

[malconium]

What I am thinking of doing is adding strips of flexible foam to the ribs before I re-attach the skins. I have some foundation sill sealer foam strips left over from a previous project that I think would be just the thing to try. These strips are 6" wide and perhaps 1/4" thick un-compressed. I anticipate that they would compress some with the installation but I need to see if the aluminum inner skins are stiff enough to still lie flat over the ribs in between rivits. My plan is to glue them on enough to stay in place until I get the inner skin in place. Also I guess that I would not want to put any on the window frames but I will have to see what that part looks like when I get to it.

On another note I mentioned that I was trying an experiment using Polyurethane glue that needs moisture to cure. I took a couple of wire tie down attachements, added a dab of the glue and stuck them on a decidedly damp ceiling (without prepping the surface in any way). They were light enough that their weight did not make them fall off while the glue set. The next day they were glued on solid as a rock. I was able to tie two romex 120volt wires to each and they held fast just fine.

I also did some looking around at Home Depot yesterday to see what other types of glue I could find that were not bothered by water. Unfortunately I have not been able to find any fast curing glue that needs water. I did find a roofing cement product that claims to be able to stick even with damp conditions. I thought I would try some on the foam strips and foil insulation to see if it would work better than the Vulkem. I will see what happens and report back here.

In the meantime I am still open to other suggestions for glue types. I did install an electric heater yesterday to see what would happen. It looks like I can drive the moisture off of the walls and maybe normal things will stick under those conditions. I will have to do more experiments and see. Actually I want the walls to be dry before I put the foam in place anyway I think. I will also try some alcohol to wip the aluminum off with before I try sticking the wire ties on with their normal adhesive.

Malcolm

[malconium]

I never would have thought that I would need more rain to continue my AS work. I want to confirm that I have all the leaks fixed in a given area of wall before I fill it up with foil insulation. The really hard rain we were having recently was giving me a very clear picture of what was leaking. There are specific areas that I think I have fixed but the rain stopped before I could do a final verification. Sure I could get a hose out but it would be a lot more realistic to have a full blown rain storm to do a final verification.

On another note I had an idea that I think I am going to pursue. I was somewhat bothered by the fact that if I put my wiring between the outter skin and the foil that I would have to carefully check my inner skin pieces before I could decide where to attach the wires and where I was going to need to cut a hole in the foil to let them through. I did not really want to have to drag out the inner skin pieces until I was closer to ready for them. So it occurred to me that there might be a way that I could fasten the wires on the inside side of the foil, make the positional adjustments as needed at the time I am installing the inner skins and maybe not have to puncture the foil in as many places. Here is what I thought to do.

1.) Attach some sort of strapping or wire between the ribs (from rib to rib) at the same level as the inner skin.

2.) Use nylon wire ties to attach the wiring bundles on the wall side of these straps wherever it seems desirable to do so.

I first thought that I could use aluminum or galvenised steel wire for this purpose but it occurred to me that the wire bundles might be able to slide back and forth some during travel. This could perhaps eventually saw into the insulation and cause shorts. It might be OK if I add some sort of sleave around the wire bundle first. I thought I would check out the garden supply section of Home Depot or Lowes to see what kind of plant strapping tape I can find that could work for this purpose. I might also consider using some of the nylon netting that I remember using in the past to hold up fiberglass insulation underneath a floor in house construction. Maybe packaging banding strapping would work if I can find some.

Anyone have any suggestions or thoughts about this? I need to find the right type of material and I need a good way to attach it to the body ribs.

Thanks,

Malcolm

[malconium]

I thought it was time to give some update on my progress and techniques with the foil insulation...

I have finally installed insulation in the entire back end cap area of my AS and have re-installed the skins and end cap back there. I have attached several photos of the process. As I explained before I have been using strips of foam insulation around the edges of a given wall cavity to suspend the foil insulation with an air gap on both sides of the foil. I found a black roofing adhesive that I have been using to glue it in place until I get the skins back in. The stuff is a bit messy to work with and I must admit I forgot to check to make sure that it does not have outgassing problems which I will have to do before I use more of it. I did also use some Vulkem 116 (relatively cheap at Home Depot) which also seems to work although it is not quite as sticky as the black glop.

One of the photos show how I drilled some 1/4" holes and glued screen over them to keep any insects out. Another photo shows the foam just around the edges of the cavity before I add the foil. It does have a bead of the goop around the edges in preparation for adding the foil. There are 3 photos that show the installed foil in place. What is harder to see is that I used foil tape as necessary if there was a joint that I needed to cover. The last photo shows the end panels and end cap re-installed at the back end.

The technique does seem to work fine but is definitely more time consuming than just stuffing the cavities with fiberglass. I will add more photos when I get futher along with the process. In the meantime I would be happy to answer any questions that anyone has about the process.

Malcolm

[malconium]

I spent some more time this last weekend installing foil insulation. I think I have the technique all worked out now. My son-in-law was able to give me a hand and between the two of use it took maybe 5 hours to do the following:

1.) Saw about 3 sheets of foam insulation board up into 1" wide strips on the table saw.

2.) Make a trip to Home Depot for more adhesive (while the sawing was going on). This time I decided to look again at paneling adhesives and etc. I had picked the black gloppy roofing adhesive before because it was the only product I could find that said it was tolerant of damp surfaces. My walls are no longer damp so I decided to try "Liquid Nails" general purpose construction adhesive. It works just great! It grabs a lot faster than the roofing adhesive and is a lot less messy to work with. I bought a box of 12 tubes for $21+ which makes it less than $2 per caulking gun tube.

3.) Install all the 1" thick foam strips around all the cavities in the front end area. Drill some drain holes along the bottom of the wall and glue on some pieces of screen.

4.) Cut, fit and glue the foil insulation in the entire front end cap area. I had been using a utility knife for cutting the foil before but found that a pair of scissors worked a lot better. This included using foil tape as necessary on joints in the foil. It was interesting to me to notice that there are a lot less framing members in the wall in the front area compared to the rear area. I can only assume that this was stock.

5.) Scrub all the aluminum inner skins that fit the front area in preparation for installing them.

That was all the time we had but I felt that the process went very well and was encouraged with the process overall. Also interestingly enough we could actually feel our body heat radiating back into the AS from the foil as we installed it.

It should take maybe a max of 1 hour to put the aluminum panels and the fiberglass end cap back in place in the front area. I also now have a big pile of foam strips to use for continuing the process along the sides of the AS. I am still happy with the choice of foil insulation and feel better about the time it takes to install and my choice of adhesive.

Malcolm

[jcferguson]

Malcom,

I am thinking of using your technique - a couple questions

Is it better for cold climates to have the larger air gap on the inside?

You used liquid nails to attach the first piece of foam directly to the outer skin, then again to attach the foil, then again to attach the inner piece of foam?

What did you decide about the spacer between the ribs and the interior skin?

Thanks for any help,

Carlos Ferguson

[malconium]

Carlos,

I am not really sure if it matters much which side has the larger air gap. I had wanted to make them both the same but I could not find any foam insulation that was 3/4" thick at Lowes. Thats why I went with 1" and 1/2". The reason that I put the 1" cavity on the outside was because I originally thought that I would put the wiring in the outer part. I have since decided to put the wiring in the inner side. I have completed both the ends of my AS with the 1" to the outside. I may very well switch for the rest of the insulation.

I did use the liquid nails as you described:

1.) glue foam strips to outer skin
2.) glue foil to foam strips
3.) glue foam strips to foil

I always put foam around the edges of a given cavity. I then tried to use some common sense as to where else to put foam in the middle. On the curved ends I was basically trying to help make the foil follow the contour of the body.

So far I have not used any kind of spacer between the inner skin and the ribs. I think that it would still be a good idea but had not made up my mind what to use. I wanted to be able to see where the rivet holes were in re-attaching the inner skin and was concerned that would be a problem if I used something opaque. Ideally what I would like is something clear like maybe a thick vinyl tape. I had thought about using thin foam sill-sealer insulation (used between the mudsill and the top of the foundation in building a house) along the ribs. It would be perfect for the job except for the fact that I could not find the rivet hole very well. I could attach it with a little liquid nails. It does occur to me that some of it is white and maybe a little transparent. Perhaps I could use marker pen around the rivit holes and it would show through the foam. I will have to try that.

Alternatively I suppose that a thin foam blanket of the same type of foam could be glued to the back side of the inner skin before it was put on. It would add to the overall insulation effect too.

What do you think?

Malcolm

P.S. I am attaching some photos of the latest progress on the front end. I found that the cabinet in the end cap was easy to remove - held in with only about 5 screws that are all accessible from inside the cabinet. I want to work on it a bit and it did make the end cap easier to lift into place. I am working on the vista view window frames before I continue with the foil. The next part of the foil is to do the street side at least up to the center channel.

[jcferguson]

Looks good Malcolm. I went to a Lowes near my home today and looked at materials - I found the insulfoam material you are talking about - they 3/8", 1/2", 1" I believe. I would like to get as much insulating as possible in my trailer as I may spend some cold periods in there.

What about that thin cork underlayment material for the spacer? You could either cover the entire backside (I think it comes in 1/8") and just drill through from the front (assuming you are re-using your interior panels... Contact cement or even spray adhesive would seem to give you enough stick to get it onto the wall, then the rivets would hold it in place. This would also seem to add a bit more insulation, as well as deaden the sound some - though for me sound isn't an issue, I "lived" in a dodge caravan last summer working on a house renovation in Catskill, NY, and I loved it when it rained, it was like sleeping in a drum, insect sounds too, cacophony!

if you stuck the spacer to the panels instead of the ribs (which would take some measuring, but nothing more than what you are already doing) you could just drill from the front side, couldn't you? Wouldn't this solve the "hole" problem? actually you wouldn't even need to measure, just cover the existing holes on the interior skin panels with the spacer and then drill, then attach...

I am going to look into the cork - I am thinking I will put in on the floor anyway. I was talking with a friend and he though of just using 1/2 inch foam over all the ribs and spaces (where the interior skin usually goes) and then attaching the interior skin over this, through to the ribs, basically add 1/2 inch the walls - I thought that getting the rivets to work through that muich stuff would be troublesome though, probably be to wavy and bumpy where the foam compressed too much.

Keep posting your progress, I well send some pictures when I decide what to do.

Thanks,

Carlos Ferguson

[jcferguson]

Just re-read your post and realized you had suggested what I just suggested back to you about the foam on the inside! I should read carefully..

I don't see a spacer on the interior of the end part there, is it just not in place yet or was it not necessary there?

Carlos

[malconium]

Carlos,

The photos I furnished are indeed before I added the spacers on the inside side. I must not have taken my camera out to the AS during that part of the session. I did add the 1/2" spacers before putting the skin on.

I don't think it would be a good idea to put foam as thick as 1/2" over the ribs before putting the skin back on. The inner skins do furnish some structural value which might not work too well with too much mushy material between the skin and the ribs.

Cork underlayment might be a good choice depending on cost. It occurred to me that thin foam is also available in the form of underlayment for floating floors. I bet it is a lot cheaper than the cork and maybe easier to punch a hole in. Spray ahesive sounds like a good idea for attachment. If I just wanted strips along the ribs I don't suppose it would be all that hard to locate them on the back side of the skin. If I used 5" or 6" wide sill sealer I could miss exact centering a bit and still be fine. One place to check for relative costs of the underlayment materials is the following:

http://www.ifloor.com/productdisplay...4455&N=9%20121

The various underlayment options are shown at the bottom of the page.

I think I will have to think more seriously about adding something. I am not too sure I want to take the end skins back off to install it there though.

Malcolm

[Foiled Again]

I get some extremely wierd ideas from time to time, so here's a strange idea I had. I'm planning on fulltiming. I'm not retired so I'll be in the trailer is some COLD weather. Now I've heard about skirting the trailer with hay bales, 2 inch styrofoam, etc. I don't think that's an idea I can use because I won't be able to leave my trailer stationary for the whole winter. If I have to go to Lynchburg or Ohio for a couple of weeks I need a "skirt" I can take with me - so weight & space are considerations. I am maintaining a storage locker where I'll stow it in the summer.

I sew.

Here's the whacked out idea. Could I really make a skirt - like a real skirt for my trailer using foil bubble insulation? I thought about using canvas and "hose carriers" straight cast iron stakes with a loop or hook on the top to carry a hose above the ground or over a flower bead. I thought I'd make a pocket at the top and stick flexible pipe insulation inside the pocket - pushing that into the lower sidewall of my trailer with the hose carriers holding up the top of the skirt and holding the skirt tight against the sidewall. I could have a bottom pocket that I'd run a garden hose through - full of water, (or Ice) that should hold the bottom of the skirt to the ground. Is the foam bubble insulation flexible enough to line the skirt with? Would it give me passable protection and help reduce heat loss under the trailer.

I also thought I could keep the underside slightly warm by throwing some lights under there, possibly even fluorescent grow lights so a campground couldn't complain that I was killing grass?

I've got a 22ft CCD so circumference would be about 56 ft, max drop 3 feet?

Comments?

Tin Lizziie

[Over59]

I would think anything that blocks the wind would help. Heat loss is by the "wind chill" not the temperature. It's hard to follow your design but the concept sounds sound. You could use snap fasterners like the boats use.

[AirConditioner]

If you like wild ideas: Howabout buying the cheap inflatable boat fenders or an adaptation of the inflatable long pillows used to surround oil spills.

Place them continuously under your Airstream, inflate them carefully, and you have a dead air space underneath.

No structural challanges.

Put a couple 100 watt shatter-resistant bulbs under there and you have further pre-heated the under chassis space. The inflated materials will not easily be blown out, and will provide great overall support for the entire rim of the unit. You'll never sink in the mud! This approach was used often by travellers with AVON Inflatables many years back to ferry cars and trucks across rivers where no bridge crossed.

[Foiled Again]

Originally Posted by AirConditioner

If you like wild ideas: Howabout buying the cheap inflatable boat fenders or an adaptation of the inflatable long pillows used to surround oil spills.

Place them continuously under your Airstream, inflate them carefully, and you have a dead air space underneath.

Interesting - sounds easy. Any idea of what cost? Where would you find these?

Thanks, Tin Lizzie

[malconium]

A couple of thoughts occur to me about your wild ideas. First of all the foil is relatively flexible but about like lighter weight cardboard. The foil would work best if it is exposed on the inside for best reflective action. You could perhaps attach it to the back side of some sort of fabric depending on the look you were after. I would guess you could sew through it if you wanted to. Some sort of glue would also work.

If you like the idea of inflatables maybe the thing to do is to consider using inexpensive air mattresses. You could perhaps make a fabric sleave to put them in that you could attach along the bottom of your AS. I don't know for sure if you can get ones that are wide enough to fill the space from the AS to the ground though.

Malcolm

[Travis_in_MD]

Hi all-

I just bought a Globetrotter because my daughter wants to travel with me this season- and I started gutting it because the interior was already missing. I want to try and update the insulation and wiring (first time for this sort of thing..) and I am amazed to say the least. I have many years experience in residential remodeling and commercial construction yet these things are very unique!


I have numerous questions I hope can be answered by the members of this forum; I will ask them one at a time in hopes of not taking up too much space.



#1 Why isn’t there a vapor barrier on these things??? I am most surprised to see that the most common of all modern building and construction products cannot be found in any form on Airstreams. Why? Aside from keeping out the moisture in your precious insulating endeavors- it blocks a lot of wind! Translation: it helps preserve internal temperature. Granted, it would be difficult to install Tyvek (or similar) around all the framing members- especially when you consider that it should (ideally) be located on the outside of your insulation. Why not just a simple plastic or Mylar sheet taped to the inner skin before insulating- Or even one located just beneath the interior skin? Am I missing something here? Please help me understand…



I was interested to read that others have considered a ‘from scratch’ approach to help reach better thermal efficiency (hay bales HAS to help somewhat! - clever). The biggest problem I see is the fundamental design itself: metal framing. In a residential basement- you must space out a metal framed wall away from the exterior wall (block, stone, concrete…) because the moisture condenses on the inside due to thermal migration. The properties of a metal framed wall, despite how well insulated they are, include “cold spots” that will migrate on the inside because metal studs conduct heat and cold much faster than the insulation. I don’t know how efficient an Airstream could ever become without encroaching on the inside space.

Thanks for any input!

[uwe]

Malcolm,

Your insulation idea makes sense. I am thinking of ripping off your idea to use on my 1963 Overlander project.
Where did you buy the foil? ( pm me if you don't want to plug the company you bought it from)
How much did you end up using? ( My trailer is 26ft, bumper to tongue, about a 22/23ft tube)

I like the idea of fiberglass insulation making contact with the interior skin for noise reduction reasons. I am thinking of closing cabinet or entry doors, general mechanical noises, as well as outside noise reduction. Do you think that the interior mechanical noise will be louder than before?
I would install thin square foot sections of noise reduction panels to the back of the interior skin.

Your project looks great! Nice job. Thanks for the updates.

[malconium]

Thoughts about moisture barriers...

I think the aluminum outer skin is going to be pretty much wind proof eliminating the need for a moisture barrier to help in that area. Also it is pretty hard to envision tyvek blocking moisture from the inside of the AS better than the inner aluminum skin does (except where there are seams and holes). The biggest problem with the potential for moisture getting into the insulation might very well be leaks from the outside. I guess the various issues about moisture in the walls is part of what lead me to decide to use foil insulation instead of fiberglass. I also drilled small drain holes in the bottom of the wall cavities to provide a way for larger amounts of moisture to get out if they ever get in.

About the metal frame...

You are absolutely right about the metal frame being a problem with achieving maximimum insulation in an AS wall. Of course so is the fact that the walls are only 1-1/2" thick. It is, first of all, unreasonable to think that we can acheive the types of insulation values that are typical in residential construction. I think the idea is to do the best we can given the starting conditions. It is, of course, true that the aluminum frame members are not as good of an insulator as fiberglass. In residential construction it is also true that the wood frame members are not as good of an insulator as fiberglass or other types of insulation. Of course wood is a better insulator than the aluminum framing. The point, however, is that in residential construction the idea is to get the best average insulation per square foot of wall given a particular type of construction that might very well have different insulation values for the different parts of the wall assembly. I think the same is true for an AS. I also think that providing some form of thermal break between the frame and the inner skin would help a lot.

Malcolm

[malconium]

Originally Posted by uwe

Malcolm,

Your insulation idea makes sense. I am thinking of ripping off your idea to use on my 1963 Overlander project.
Where did you buy the foil? ( pm me if you don't want to plug the company you bought it from)
How much did you end up using? ( My trailer is 26ft, bumper to tongue, about a 22/23ft tube)

I like the idea of fiberglass insulation making contact with the interior skin for noise reduction reasons. I am thinking of closing cabinet or entry doors, general mechanical noises, as well as outside noise reduction. Do you think that the interior mechanical noise will be louder than before?
I would install thin square foot sections of noise reduction panels to the back of the interior skin.

Your project looks great! Nice job. Thanks for the updates.

Uwe,

I found my insulation at Lowes. It is the Reflectix brand. I bought 4' wide rolls. I don't have my calculations in front of me relative to how much I bought but I can give you a hint as to how I calculated the amount to start with (I have not finished installation so I might be off). I measured the distance from the floor to the center of the ceiling (along the wall and in feet) and multiplied that by 2. I then took the entire length of the inside of the trailer (in your case about 23') and multiplied it by the above measurement to get an aproximate area to buy. I thought that would be enough to do the end caps since I would not need to use foil where the window, door, wheel wells and other openings were. Since I found my foil locally I thought it would be pretty easy to buy a little more later if I ran out before I was finished. If I remember correctly the distance from the floor to the center of the ceiling is about 8 feet. That means 8' * 2 * 23' = 368 sq feet. You will have to round off to the nearest roll amount and thats where I would start if I were you.

I frankly don't know about the noise issues with the foil as compared to fiberglass. I have no experience with how it sounds in normal conditions so I will have no metric for noticing any difference. Ignorance is bliss they say. As a practical matter adding the fiberglass might reduce the effectiveness of the foil a little bit since it seems to do better with an air gap next to it. How much reduction I don't know. What you might consider doing is to do what I have done in the larger cavities (not particulary on purpose for sound reduction but to help keep the foil centered). I glued 1" wide foam strips or even just smaller pieces of foam on both the outside skin and on the inside of the foil. That might very well do the same thing as you are thinking about with the fiberglass.

Malcolm