Insulation preference

[Andy Moreau]

Hello,

We are renovating our '76 sovereign from the ground up. We are almost to the point of putting the walls back onto the skins and are debating which type of insulation to use.

Has anyone used reflectix before? Pros/cons?
If you have used it have you been happy with it?

We live in North Florida and will probably not be doing any extreme cold weather camping with our airstream.

Any advice is appreciated,
Thank you!

[batman]

Hello Andy,
I am sure there are existing threads on this subject already.
However, I used a combination of Prodex and Johns Manville blue fiberglass (no formaldehyde) like a sandwich.
Here is a review of Prodex vs Refletix, etc. https://www.insulation4less.com/insu...hield-etc.aspx

Regardless of which product you use you will have to use foil tape to create a sealed air space between the ribs. Even then we AS owners have the distinct disadvantage of having metal (aluminum) ribs that will transfer cold or heat from the outside skin to the inside skin regardless of all the insulation in the world between the skins. Plus having NO double pane windows is another source of cold/heat transfer. Prodex or reflectix can be easily cut to fit the windows and vents.

P.S. Don't forget the underside of the sub-floor I used 2" of foil backed foam board, glued and screwed( 2 1/2" screws with 1/4" fender washers) to the bottom of the ply.

Best of luck,
-Dennis

[Bubba L]

We did basically what Dennis did. I think Prodex is far more superior than Reflectix. We placed one layer against the outer skin using 3M spray adhesive and ran all the wiring noting wire locations on a drawing. Then we cut some 1/4” x 1” foam strips on the table say. We stuck the strips to the first layer of Prodex with double sided tape to create a dead air space. Then stuck the last sheet of Prodex and sealed with aluminum tape. So far so good. Some have coated the ribs as a thermal break. As Dennis said, insulating underneath the subfloor is important. Good luck

[skyguyscott]

Asking on this form which insulation is best is a little bit like asking which is the true God, or what is the best tow vehicle.

Dennis is steering you true: If you do a search on this forum you will uncover many long and fascinating threads, including those who have renovated with great pictures.

Among the insulating materials used, you have fiberglass, rock wool,, bubble foil like prodix and reflectix, Various flavors of spray foam, various types of closed cell foam panels And discussions of more exotic material like aircraft insulation and aerogel.

I encourage you to do some research because you will undoubtably learn a lot. But the bottom line is that there’s only so much that you can do in the one and a half inches of space airstream gives you, and even if you were to find the perfect insulator, which does not exist, you would still have the aforementioned substantial thermal bridging between the outer aluminum skin thru the aluminum ribs to the aluminum inner skin. Some have suggested using some sort of double sided foam tape on the ribs to act as a thermal break to help mitigate the very substantial problem. But even then there are still the large single pane windows.

Make sure you understand the difference between radiated heat and Infared. The type and method of installation will also depend if you were more concerned about keeping it cool or about keeping it warm.

The bottom line is: select the best insulation your time and budget and patience will allow, but not to expect too very much because airstream trailers are fundamentally not four season trailers due to their aluminum construction and single pane windows.

[Andy Moreau]

Thank you Dennis! I have 3 or 4 inch foam board on the bottom. Also, I keep hearing about this air gap. Could you explain this a little more for me? I will use the Prodex. I've seen a few different thicknesses. I would imagine the thicker the better? like .4" was "thick".

[Andy Moreau]

Originally Posted by Bubba L

We stuck the strips to the first layer of Prodex with double sided tape to create a dead air space. Then stuck the last sheet of Prodex and sealed with aluminum tape. So far so good. Some have coated the ribs as a thermal break. As Dennis said, insulating underneath the subfloor is important. Good luck

I see! so when you sealed with aluminum tape, you sealed it all away from the inner skin? Last question, Did the thermal break work good enough to actually go through it again? Thank you Bubba

[Bubba L]

Originally Posted by Andy Moreau

I see! so when you sealed with aluminum tape, you sealed it all away from the inner skin? Last question, Did the thermal break work good enough to actually go through it again? Thank you Bubba

Prodex has aluminum foil on each side. My intention was to tape all the joints with aluminum tape to create a dead air space within the wall cavity. If I remember correctly, we may have coated the rib face for a thermal break, but don’t remember. If I find it in my notes I’ll let you know. Thanks

[Lumatic]

Reflectix has no insulating value but it does reflect radiant heat. Use it next to the inside and outside walls. For the insulation a foam core insulation is about twice as effective as the pink stuff or rock wool but does not bend around curves easily.

[skyguyscott]

Originally Posted by Lumatic

Reflectix has no insulating value but it does reflect radiant heat. Use it next to the inside and outside walls. For the insulation a foam core insulation is about twice as effective as the pink stuff or rock wool but does not bend around curves easily.

Exactly. Think of reflective bubble wrap as an umbrella. It creates some shade that will help a little bit to keep you cooler. But, like a real umbrella, it will do nothing to help keep you warm.

What is happening is that it is reflecting the infrared radiation from outside, but you must have a gap between the reflective material and the inside of the outer skin for it to work.

[batman]

Originally Posted by Andy Moreau

Thank you Dennis! I have 3 or 4 inch foam board on the bottom. Also, I keep hearing about this air gap. Could you explain this a little more for me? I will use the Prodex. I've seen a few different thicknesses. I would imagine the thicker the better? like .4" was "thick".

Hi Andy,
"Air gap" may be a misnomer, but in the case of using a foil backed insulator (thicker is better) it referrers to the space created by sealing the area between the ribs. For example If you are inside the trailer looking at the inside of the outer skin with a vertical rib on the left and one on the right. The C-channel on the floor and a horizontal spacer somewhere toward the top or middle of the wall. I cut a piece of Prodex to fit in that space against the outer skin, Johns Manville fiberglass in the middle "air gap", then cut a piece of Prodex that fits the inside and seal with foil tape at all sides of ribs , C-channel and cross members and you have created a sealed air space, "air gap". Thus utilizing both types of insulating properties in a very limited space.


I am not an expert on thermal dynamics and I am sure some one else here can explain it much better. Hope that helped.

-Dennis

[kidjedi]

My research and thoughts...

http://beahmstream.com/insulating-an...ch-and-theory/

http://beahmstream.com/insulating-an...l-application/

[Bubba L]

Originally Posted by kidjedi

My research and thoughts...

http://beahmstream.com/insulating-an...ch-and-theory/

http://beahmstream.com/insulating-an...l-application/

Good information. Thanks

[skyguyscott]

Originally Posted by kidjedi

My research and thoughts...

http://beahmstream.com/insulating-an...ch-and-theory/

http://beahmstream.com/insulating-an...l-application/

This is the most thoroughly researched and practical report I have ever read on the subject. Unless and until anyone goes to the bother of doing exhaustive testing with tons of data points, this will be my authoritative article on the subject of insulating airstreams. This should be required reading for anyone serious about how best to insulate their trailer. I hereby nominate you for the Nobel prize in airstream research!

By the way, do you plan to do anything about the single pane windows?

[batman]

Originally Posted by kidjedi

My research and thoughts...

http://beahmstream.com/insulating-an...ch-and-theory/

http://beahmstream.com/insulating-an...l-application/

Well done. I wish I had this when I did my renovation.
Thank you master jedi.

-Dennis

[perryg114]

I used 2 layers of 1/2" RMAX. This works well and does not suck up water like the stink pink fiberglass stuff. This already has an aluminum skin so it also acts as a radiation barrier. Best R value is spray urethane foam.



Perry

[kidjedi]

Originally Posted by skyguyscott

By the way, do you plan to do anything about the single pane windows?

First, thanks, all, for the positive comments. It's good to know that the extra work of researching and sharing information is being put to use and helping others.

In regard to the single pane windows... my center end and curved panoramic windows are double pane, so ahead of the game a bit there. With the others, I currently have custom made "pads" (ripstop water proofed nylon over quilted padding with a flexible sheet core) that I place in the windows during the winter, and in the summer the single pane with awnings or shades have sufficed so far.

I've been working on a couple of magnet based panel systems (basically storm windows), and have some ideas I like, but I'm still working on aesthetics and the supply line (to keep cost down).

It's worth mentioning that for keeping out summer heat, a simple do-it-yourself reflective window tint (film) will make a *huge* difference.

[Hein]

We sell A LOT of 3M Thinsulate SM600L automotive grade acoustic/thermal insulation to the van conversion market. It would be an excellent product for an Airstream renovation. We would be honored to work with you and can offer you some special pricing. Please reach out if interested.


All the best,
Hein
DIYvan
541 490 5098

[Hein]

We sell A LOT of 3M Thinsulate SM600L automotive grade acoustic/thermal insulation to the van conversion market. It would be an excellent product for an Airstream renovation. We would be honored to work with you and can offer you some special pricing. Please reach out if interested.

We also stock Low-E in a 72" width. It is similar to Prodex and made here in the US.

All the best,
Hein
DIYvan
541 490 5098

[batman]

Originally Posted by Hein

We sell A LOT of 3M Thinsulate SM600L automotive grade acoustic/thermal insulation to the van conversion market. It would be an excellent product for an Airstream renovation. We would be honored to work with you and can offer you some special pricing. Please reach out if interested.

We also stock Low-E in a 72" width. It is similar to Prodex and made here in the US.

All the best,
Hein
DIYvan
541 490 5098

3M Thinsulate seams like a almost perfect product for AS use. 1 3/4" thick fully expanded, Hydrophobic and sound absorbing but only R-5.2. I think it was designed for acoustic use more than insulating. It would probably be better used in conjunction with something like a Prodex type product to be an efficient insulator. It sounds like it could get quite expensive.

-Dennis

[malconium]

The following threads are relatively old but have a lot of good information about foil insulation and even about some tests that were conducted to attempt to asses the relative merits of different types of insulation.



http://www.airforums.com/forums/f46/...cks-30196.html


http://www.airforums.com/forums/f4/i...lts-13953.html


http://www.airforums.com/forums/f474...red-13363.html


Especially check out post #59 in the above thread where I seem to have waxed somewhat eloquent regarding the topic of insulation.



I would also like to say that the techniques I used and documented in the first thread above have proven to be fairly effective. My wife and I have been living full time in our Airstream for a bit over 2-1/2 years now while I build our permanent retirement home in Central Oregon. Its taking a while to build mostly because I am doing most of the work myself. Anyway we are now in our third winter here and find that we can keep our Airstream comfortable enough with a combination of a coupe of electric radiator heaters and a backup "Little Buddy" propane heater. We have found that a dehumidifier is sometimes needed to manage the moisture levels. We also have a 2" rigid foam skirt built around the bottom of the trailer with a small heater underneath to help keep our drain plumbing from freezing.