Insulation effectiveness tests

[boatdoc]

Originally Posted by filterman

Boatdoc thanks for this info "Prodex gives you R-14 with 1" air space for 1/10 of the cost and 1/50th in weight. I agree with you that aluminum tape will not always hold up, but 3M has adhesives that will. Adhesion depends on surface cleanliness especially when installing aluminum tape"
What is your recommendation for the minnesota mining and metal tape? Thanks Save your plans on those jacks I amy be interested in having you make me some in the future. And it really just about trying to make it perfect isnt it? Afterall its fun to create and experiment. Ok so I think I have rear end separation and found a 34 foot frame from a roll over for 300 bucks so I was thinking could I use that frame and my shell and have the extra three feet for a gene box? I am probably gonna have to replace the floor so I will have to raise the body and instead of working this frame I would just pull it out and use the other, it has new axels also. What you think?

ps airstream did make an arctic package in the 60's the floor was urethane foam sprayed; so I am told by Empire in Ca.

Hi filterman;
Sorry, but I am not familiar with the metal tape you talking about. In reference to frame replacement you need to consider weight balance. Larger frame may have axles too far back to have 10% tongue weight. Repositioning of axles may be necessary as moving the rear head shell mounting plate, possibly much of the plumbing and other items. Check the laws pertaining to overhang past the shell. You may have to cut the frame shorter pending length of your shell.

In reference to the Arctic package all I can say is that it can be done providing the frame is prepared for it, so that moisture cannot travel via steel frame in contact area between steel and foam. Final epoxy protective coating over foam can greatly reduce the moisture absorption.
Thanks, "Boatdoc"

[malconium]

I remain a strong advocate for the use of reflective foil insulation. I also have discovered an alternative supply for way cheaper foil and have a slightly modified approach that I would take if I were going to re-do the bubble foil in my Airstream - which I most certainly am not going to do.

The following website has a product called "Ra-flect Radiant Barrier"

Aluminum Radiant Barrier Insulation | Ra-flect Radiant Barrier

I am remodeling my back porch so that it is a glassed in sun room. I wanted to add reflective foil insulation and went to Lowe's to buy some more of the same type that I used for my Airstream - Refletix brand bubble pack. They currently no longer stock the product in 48" wide and 16" wide. I bought a couple of rolls of the 24" wide product because it would work for part of what I needed. I paid something like $25 for a roll that I think covers about 50 square feet. That makes it about 50 cents per square foot. I was going to need about 330 square feet of foil for the ceiling and I really wanted it in a 16" wide roll because of the ceiling joist spacing. At 50 cents per square foot that would run about $160. I started checking out other local stores and my Internet bookmarks. I ended up buying one roll of 16" wide Ra-flect foil for a total of $66.62 of which $20 was for shipping. The single roll was 333 square feet.That works out to just under 20 cents per square foot even with the shipping charge.

This particular product does not have a bubble pack core so it is thinner. The entire roll was only about 5" in diameter and weighed in at about 10 lbs for shipping. The core is a woven polyethylene material instead of bubble pack or foam.

So here is what I would do if I were going to do it again:

I would use 1/2" thick foam strips as spacers around the edges of the cavities and I would suspend two layers of the foil inside of my walls. So that would be spacer - foil - spacer - foil - spacer. I might leave out the last spacer if I was comfortable enough with the glue I used to hold the foil in place. Technically if I used all the spacers the glue would only need to hold the foil in place during the assembly. I think that the foam spacers would clamp the foil pretty well once the inner skins are back in place. Two layers of reflective foil surrounded by air gaps would make a very good reflective insulator. I have a 31' Airstream and I think that the 48" x 250' roll might just about be enough for two full layers. At a base price of $126.96 that could be a pretty good deal even with the extra shipping charge. That is only about 13 cents per square foot for one layer. Even with two layers that works out to be 26 cents per square foot. I checked and the shipping charge for the big roll is the same as what I paid for my small roll - namely $20. That amounts to only 2 cents more per square foot. I think that would be a great way to go...

Malcolm

[Wabbiteer]

Not to be a naysayer but 1 - 4 ft x 175 ft roll (700 sq ft) of Prodex comes in at 38¢ sqft delivered, absorbs some sound and does not completely depend on reflective properties to insulate...

[filterman]

What about sandwich reflect with half inch foam then prodex then reflect then prodex etc. But what would then be the best adhesive to use and do you want to seal airtight against the skin or allow the outter skin to breathe a little so to speak. Dont want to trap moisture in the outter layer and the as skin. And how do you get straight foam sheet to comply with the curves of the shell of the as?

[Zeppelinium]

Originally Posted by malconium

...
The following website has a product called "Ra-flect Radiant Barrier"

Aluminum Radiant Barrier Insulation | Ra-flect Radiant Barrier

...

Don't confuse a radiant barrier with insulation. You will regret it when your air conditioner is working it's butt off in Georgia in the middle of the night when it's still 95 degrees and 95% humidity.

Zep

[malconium]

Originally Posted by Zeppelinium

Don't confuse a radiant barrier with insulation. You will regret it when your air conditioner is working it's butt off in Georgia in the middle of the night when it's still 95 degrees and 95% humidity.

Zep

Zep,

Wow - I don't believe that you just said that! I hope NASA didn't read that!

Insulation by definition should include any approach that reduces the flow of heat from one location to another. Heat can move from one space to another by three different methods of heat transfer: conduction, convection and radiation. In a typical house or trailer more heat is lost through the walls, roof and floor by radiation than by any other means. If I recall the numbers correctly something like 80% to 90% of the heat loss through the roof and walls is by radiant energy transfer. It is more like 95% through the floors. Reflective foil has the ability to block as much as 95% of the radiant energy that is trying to get past it. If you can block 95% of 80% to 90% of the heat that is trying to move from one space to another I contend that should qualify as insulation.

The radiant principle works both ways too - namely heat trying to get out or heat trying to get in. My guess is that and even larger portion of the heat trying to get into our Airstream during a hot day is of type radiant - unless we are parked under shade. The key to the effective use of reflective foil is to have reflective surfaces pointing both inward as well as outward with an air gap in front of them. The air gaps also provide some blockage to heat transfer by both conduction and by convection if the cavities are sealed. Having two layers of reflective foil with a 1/2" air gap in between should be at least as good as having a single layer of reflective foil with either a foam or bubble core. You also end up with more reflective surfaces to block the flow of radiant energy with the two layers.

Any kind of insulation has one problem during hot nights. If you do not have air conditioning and you allowed the interior to heat up during the day the insulation will make it harder to get the heat out even if the outside temperature drops quite a bit at night. The best we can do under that condition is to pull cooler air from the outside into our units using the ceiling fans. If it is 95 degrees outside the best we can do for the inside without AC is 95 degrees. If you do have AC the reflective foil is still going to keep the outside heat from coming in at night.

Here is a site that has a great explanation of the physics of reflective foil. I see that this site put radiant transfer up and out more like 70%. That is still quite a bit. Further down in the writeup is case #3 that is very much like the two layers of foil that I described wanting to do. It seems to be a pretty effective barrier to heat transfer.

http://www.radiantbarrier.com/physics-of-foil.htm

Malcolm

[Zeppelinium]

Originally Posted by malconium

.. My guess is that and even larger portion of the heat trying to get into our Airstream during a hot day is of type radiant - ...

The opperative term is "during the day." You better watch out, I'll get out my 1968 thermo book and start expounding on the balance between radiant, convective, and conductive heat transfer...

Hey, I'll loan you the test aparatus and computer I used--you make up the test cell and run the test. We are all anxious for the data! I'd love it this foil beats out glass batts.

Zep

[Jammer]

Here we go again...

[malconium]

Originally Posted by Zeppelinium

The opperative term is "during the day." You better watch out, I'll get out my 1968 thermo book and start expounding on the balance between radiant, convective, and conductive heat transfer...

Hey, I'll loan you the test aparatus and computer I used--you make up the test cell and run the test. We are all anxious for the data! I'd love it this foil beats out glass batts.

Zep

Zep,

I am completely willing to participate in whatever way makes sense to do some testing. I did however notice the following quote in the explanation of the physics of reflective foil that gives me some pause:

"In spite of the advances made by space technology in insulation systems based on understanding and modifying the effects of radiation, no universally accepted laboratory method has yet been devised to measure and report the resistance to heat flow of multi-layer foil. Until such a method that will satisfy rigorous laboratory demands is devised, we must be content to make our judgments on the basis of common sense and experience."

So the big question is how best to formulate a real world enough test within which we can properly compare my suggested two layers of foil with the other approaches that have been discussed. Over a long period of time I have tried to read up on everything that comes my way relative to the effectiveness of reflective insulation and feel like there is a lot of compelling information on the subject. Given the above quote I am not sure how the testing was done for this writeup though. The article shows some diagrams that supposedly represent a wall cavity that is only 1-1/2" thick - exactly what we have in our Airstream walls. The diagram with two layers of foil includes the following comentary:

CASE 3, TWO SHEETS OF (5% EMISSIVE) ALUMINUM FOIL divide the wall space into 3 reflective compartments. Heat loss by radiation drops 94% from Case 1. The 2 interior sheets retard convection so that its flow falls 75%. Conduction rises only 2 BTUs; from 21 BTUs to 23 BTUs. The total heat loss drops 85% from Case 1.

Case 1 has nothing but air in the wall space.

I would suggest that we collectively do some Internet surfing to see if we can find other well founded articles that talk about the relative merits of different insulation types - articles that are based on actual testing. I also suggest that we rule out very expensive types of insulation as being impractical.

I am also open to suggestions on what kind of test I could do to validate my suggestion for the two layers of foil that would adequately compare it with other types. Zep - is your test box still set up? Could I perhaps furnish panel materials for you to use with the set up? Should I consider dusting off the test panels that I used out in the sunshine and modifying them so that I can re-run some test with my IR thermometer? What do we think would be sufficiently conclusive?

Maybe some of you folks that have installed foil insulation in your Airstream could give us some feedback on how you think it is working. That would be especially useful if you can somehow give us a before and after comparison. My unit is still not road worthy yet so I don't have any good way to do report on its success. I also do not have any before information.

Malcolm

[malconium]

Originally Posted by Wabbiteer

Not to be a naysayer but 1 - 4 ft x 175 ft roll (700 sq ft) of Prodex comes in at 38¢ sqft delivered, absorbs some sound and does not completely depend on reflective properties to insulate...

Wabbiteer,

I like the Prodex product. It is a better deal from a price point of view than the bubble foil that is typically available from HD or Lowes. I would also expect it to perform better. I in fact wish that I had known about it when I was putting bubble foil in my Airstream walls. In my opinion going with a single layer of it would be a very good choice. The following website claims
an R value of 15.67 for it which is definitely better than 1-1/2" of fiberglass.

Insulation for Less : Prodex : Reflective Insulation : Pole Barn Insulation : Metal Building Insulation : Bubble Insulation

At 38 cents per sqft it is still more expensive than 28 cents for two layers of the Ra-flect foil though. I am not sure but it seems like a 1/2" air gap between the two layers of foil would provide some noise abatement. Whether or not it is as much as what the Prodex product offers I don't know. I would feel comfortable going with either Prodex or with Ra-flect but I am still inclined to favor the two layers of Ra-flect over a single layer of Prodex. The air gap between the two layers does by the way mean that the Ra-flect is not only working to stop radiant energy. The article about the physics of foil says that it pretty significantly reduces heat flow by convection too.

Malcolm

[malconium]

I just noticed that the Ra-flect type of reflective insulation is available in a version that is laser perforated with small holes to allow breathing. I remember that Andy from Inland once said that using foil insulation was not a good idea because he thought that it would trap moisture in the walls. Because of his comment I drilled some holes in the base of my walls that I lined with some screen to keep insects out so that if any moisture did accumulate it might have a way of draining out. I think this perforated Ra-flect might very well be a good way to go in that it would allow the wall to breathe better perhaps eliminating Andy's concern in that regard. The price is the same for the perforated variety too by the way.

Malcolm

[Wabbiteer]

The following website claims an R value of 15.67

That is in their absolutely perfect test conditions - " Prodex with an airspace of 2.64 inch on each side of product." <-- read that as perfectly dead lab conditions airspace.

Mostly what their advertising points out (hype) is that hot air naturally wants to rise so at deflecting heat upwards its a super product - but not so good when the heat snuggles against it trying to rise past it as it is in a heated interior in cold weather.

- single layer R value of 6 trying to block 'heat up' transfer (or cool down)
- single layer R value of 7 trying to block heat 'horizontal' xfr.
- single layer R value of 15 trying to block heat 'down' xfr. (or cool up)

Mostly we need to think compartmentalization, with less than their tested air space then installing baffles in dead air spaces is important. That is to keep the vertical chimney effect from allowing superheated air from collecting at the very peak or super-chilled air from gathering at wall bases.

Also, point of context - the foil is tested 'clean'. Add pollen, road dust, oxidation, cooking fumes, anything that deposits on the reflector and the insulative properties crash. I read somewhere the rippled surface of Prodex might fare better over time with not exposing 100% of the surface to every draft of air leaving behind residues.

I committed to using the bifold pink-foam sheathing insulation (70% off at HD store closing) and prodex plus blue-foam sheet under roof proper and some fiberglass in certain areas to block sound in the next month - trailers stripped except liner sheets right now...

[filterman]

Hummmmmm

Originally Posted by Zeppelinium

The opperative term is "during the day." You better watch out, I'll get out my 1968 thermo book and start expounding on the balance between radiant, convective, and conductive heat transfer...

Hey, I'll loan you the test aparatus and computer I used--you make up the test cell and run the test. We are all anxious for the data! I'd love it this foil beats out glass batts.

Zep

[filterman]

Well???? Do we glue to the AS walls. Wouldnt the bubbles in the bubble insulation work to help hold therms and if used with the raflect work better than either product by itself. Cant we combine the two and get a better result and yes with air pockets between them?

[filterman]

It is terrible. i would rather use horse manure to insulate. I have a customer who lost his vision due to an infection from fiberglass intrusion into his eye through his protective eyewear. It is made of glass which the body cant dissolve or absorb, it gets into everything permanently and is a respiratory irritant, it absorbs water and allows for mold, fungus and who knows what else to grow. Absolute garbage! sorry I have had bad experiences with this stuff I would rather loose the r value to not have it especially in a small trailer. Just me two cents. he he AND when it gets into the living quarters it is pulverized into smaller particles so it can be passed through almost all conventional heating system filters to be breathed in and scratch away at the cilia of the lungs and inpregnate itself into the : aievoli of the lungs causing scar tissue and on and on. I would never ahndle this stuff without complete eye protection sealed and repiratory filters that are at least HEPA or better and a painters suit. Ok I feel better now.

[boatdoc]

Originally Posted by filterman

What about sandwich reflect with half inch foam then prodex then reflect then prodex etc. But what would then be the best adhesive to use and do you want to seal airtight against the skin or allow the outter skin to breathe a little so to speak. Dont want to trap moisture in the outter layer and the as skin. And how do you get straight foam sheet to comply with the curves of the shell of the as?

Hi fliterman;
There are two things you can try to form a straight sheet of foam into the curve of the end caps. Try threat by destruction, or have one custom made if the money is no object. One of them is guaranteed to work. "Boatdoc"

[filterman]

I am on the road a lot and used to drink about two to three mountain dews in the twenty ounce plastic bottle and when done toss it sealed on the passenger floor at the end of the week it was full of bottles. Now when I lived in Minnesota the winters would be cold and I remember that when I cleaned my car out at the end of the week heating it up between apointments was taking longer than without the bottles in the front seat than with soooo the bottles were holding the warmer air in them and releasing it slowly into the cab of the car thereby allowing for more heat to remain in the car. Sooo then if that theory applies to the bubble wrap wouldnt the little airpockets in the bubble wrap do the same thing? I am thinking so and with the combination of other materials maybe we can come up with a sandwich that would work really well.

[ticki2]

Originally Posted by filterman

I am on the road a lot and used to drink about two to three mountain dews in the twenty ounce plastic bottle and when done toss it sealed on the passenger floor at the end of the week it was full of bottles. Now when I lived in Minnesota the winters would be cold and I remember that when I cleaned my car out at the end of the week heating it up between apointments was taking longer than without the bottles in the front seat than with soooo the bottles were holding the warmer air in them and releasing it slowly into the cab of the car thereby allowing for more heat to remain in the car. Sooo then if that theory applies to the bubble wrap wouldnt the little airpockets in the bubble wrap do the same thing? I am thinking so and with the combination of other materials maybe we can come up with a sandwich that would work really well.

Did it also heat up sooner for the first appointment in the morning ?

[ddstech]

Originally Posted by boatdoc

Hi filterman;
Sorry, I was under impression that you were promoting the use of 16 lbs density.
I was told that the foam used in my Race Boat weighted 2.5 lbs per cub/ft, but it was crossed linked with undisclosed but very expensive component.

All and all I do not see how you can install a pour foam on a vertical surface. It would have to be sprayed and that is not a DIY job. Constant moisture will eventually penetrate the surface with time. In addition, IMHO 2 lbs density foam is much too fragile to be installed under flexing condition. Zep has done plenty of extensive research on this subject, pointing the way to what works and does not. I respect his findings. One should also consider the cost vs the value in effectiveness. Thanks, "Boatdoc"

Boatdoc, the solution is simple, put entire trailer on a rotisserie and pour away.

[filterman]

you just gotta hang upside down in the trailer and start pouring into a fan.Or send the materials to Tiger foam and have them put into a pressurized tank or make your own and use inert gas to pressurize system for spraying you would still have to deal with the curing temps being high however I have found flooring that can withstand the heat. Plastic Lumber Depot offers Plastic lumber Plastic wood Composite decking Recycled plastic lumber decking maintenance free decks maintenance free decking pvc decks pvc decking composite decks recycled decks recycled decking patio decking backyard dec look at the specs on the fireboard. Now I am only talking about foaming the bottom of the floor. So only the frame and flooring and pipes would be subject to the heat I can insulate the pipes against the heat somehow or use metal going through the floor. Thats it, use metal pipe thin walled for all floor cutouts and flip the frame and pour away. I recall hearing it takes about six people to do this.
tiki2 I think so. I just remember it not being cold as much got me thinking about recycling plastic bottles into buildings. I knew a cust who used bottles for a wall ite cas concrete and bottles very cool. they were not sealed so it was just neat looking, the bottle tops I mean they were open. I think I will go with the foil in the walls with airspace and boxed with foam and sikaflexed together, two layers. 'The bottom I am thinking still. I like the structural foam because it would strenthen the frame somewhat but i will handle that one later.