Insulating a Burro

[Andy B]

I am restoring a 1980 Burro 13, although restoration has slowed down due to the cold weather. The cold has me thinking about adding insulation between the inner and outer shell. I am not a fan of Reflectix and was thinking of adding flexible closed cell foam insulation like polyethelene. It would be easy enough to glue 1/2" sheets of flexible foam to the outside walls below the cabinet level. Getting the insulation sheets between the shells up higher without leaving gaps would be more difficult. I am replacing all the windows so that may help with access.

I was also thinking of using "foam in place" insulation (like Great Stuff) between the shells, but I am not sure how I could tell if I got full coverage, or if there were gaps. The expanding foam might distort the shells, although there is foam available that expands less and is used around house windows and doors to avoid distortion.

The body is currently off the frame as part of a floor replacement and I was thinking of adding an insulating foam sheet between the floor and frame before putting the body back on the frame. Depending on the type of foam, I may add a plywood panel beneath the foam to protect it from road debris.

Has anyone used expanding foam in a double wall egg?

Anyone installed sheets of insulation between the double walls? If so how did you slide it up to the top, some places have a very tight fit.

Anyone add floor insulation between the frame and floor?

Thanks for any advice and insights.

Andy

[Kevin A]

I know this topic has come up before, so you want want to try a quick search for insulation/Burro/UHaul/double wall, etc. Some folks have tried the Great Stuff, but caution about the expansion and distortion. I think the toughest places are in the upper walls, since the two shells pinch together a bit. The best time to do all of this is when you have the shell as exposed as possible, with cabinets removed or at least opened up. Good luck!

(We have a similar construction in our UHaul VT, but find the air gap insulation good enough for our minor cold weather camping.)

[Andy B]

Originally Posted by Kevin A

I know this topic has come up before, so you want want to try a quick search for insulation/Burro/UHaul/double wall, etc.

Thanks Kevin, I had already searched and that is why I posted, to see if there was any additional experience.

In my search I did not find anything about anyone insulating between the floor and frame.

I saw some cautions that expanding foam could cause deformation of the shell but did not find any good or bad experience from people that had actually tried it.

Found some posts about sliding insulation between the shells, but no mention of how much coverage that they were able to get.

Thanks for the reply, Andy

[Robert Johans]

Originally Posted by Andy B

Thanks Kevin, I had already searched and that is why I posted, to see if there was any additional experience.

In my search I did not find anything about anyone insulating between the floor and frame.

I saw some cautions that expanding foam could cause deformation of the shell but did not find any good or bad experience from people that had actually tried it.

Found some posts about sliding insulation between the shells, but no mention of how much coverage that they were able to get.

Thanks for the reply, Andy

I have heard folks caution against using expanding spray foam for another reason: over time road vibration causes the foam to break down into dust. Trapped between walls, with no where to go, perhaps this isn't a big deal, but no doubt your insulation values will be lost.

[Andy B]

Originally Posted by Robert Johans

I have heard folks caution against using expanding spray foam for another reason: over time road vibration causes the foam to break down into dust. Trapped between walls, with no where to go, perhaps this isn't a big deal, but no doubt your insulation values will be lost.

Robert, thanks for the heads up about vibration, I will have look into that. The Great Stuff product description says "Seals and insulates vans and campers." So I expected that it would work in an egg, but maybe there are long term issues. There are also other types of foam in place materials, maybe some degrade and others do not.

Andy

[Andy B]

I did some searching and found a 10 page discussion about foam insulation deterioration to powder on an Airstream forum.

Spray Foam Insulation - Airstream Forums

After reading all 133 posts I came away with the following:

1) There are many different types of foam in place insulation.
2) Insulation foam technology has evolved and improved considerably over the years.
3) No mention was made of what type of foam turned to powder.
4) Some foams installed 20+ years ago look like new with no deterioration.
5) Some foam manufacturers when contacted say their foam will not powder.
6) This type of foam has some of the highest r-values available
7) The foam would bond the inner and outer shells together and increase strength considerably.

Andy

[Andrew Gibbens]

I presume the Airstream discussion was about spray insulating the inner side of their single-skin trailers, like a house. So the question about the durability of the foam is relevant, but not the installation process.

Inject/pour-in-place foam has long been used in the boat industry but only when both mouldings are clamped in heavily-reinforced moulds - the forces that can be produced during the foaming process are huge.

I wouldn't be surprised if injecting just one or two seconds too much foam between a Burro's skins would not only deform the exposed panels, but also break some of the weaker joints - for example, popping the furniture off the now-distorted walls.

If I were going to do this (which I wouldn't...) I would build a little test rig - something like a 24"x24" sandwich of 1/8" ply inner and outer skins screwed to 1x1 framing around three sides - and then try out injecting foam in the gap. A broken test rig is soo much better than a broken trailer.

[Andy B]

Originally Posted by Andrew Gibbens

I presume the Airstream discussion was about spray insulating the inner side of their single-skin trailers, like a house. So the question about the durability of the foam is relevant, but not the installation process.

Inject/pour-in-place foam has long been used in the boat industry but only when both mouldings are clamped in heavily-reinforced moulds - the forces that can be produced during the foaming process are huge.

I wouldn't be surprised if injecting just one or two seconds too much foam between a Burro's skins would not only deform the exposed panels, but also break some of the weaker joints - for example, popping the furniture off the now-distorted walls.

If I were going to do this (which I wouldn't...) I would build a little test rig - something like a 24"x24" sandwich of 1/8" ply inner and outer skins screwed to 1x1 framing around three sides - and then try out injecting foam in the gap. A broken test rig is soo much better than a broken trailer.

Andrew, the test rig is a good suggestion, but even with good test rig results with a uniform gap, the gap between the trailer shells varies in size considerably in different areas and would produce different results. My major concerns are not the powdering of the foam, as some types remain flexible, but rather how to effectively fill the gap between the shells without over filling. Most of the areas to be filled have no visual access and I can not think of a way to insure they get filled but not over filled. If someone has tried it, I would love to hear their experiences, good or bad.

There is a similar issue if sheets of flexible foam are inserted between the shells. Visual access is limited and there are compound curves involved. It would be difficult to insert sheets of foam without leaving large gaps between sheets and no way to fill those gaps. Getting sheets of insulation to some areas would be very difficult. It would be great to hear from anyone that has tried this and any methods used to get the insulation to some of the more difficult areas.

Thanks,
Andy

[Matt in SV]

I was in Orchard Supply today and they were selling bags of large bean bag pellets. Theirs are much bigger than the old tiny pellet size I'm familiar with. They're about 3/16" and about $12 for maybe 2 or 3 cubic feet. I wonder if you could seal the lower edge with expanding foam and then blow these things in through the roof fan access, or up from the bottom. They should find their own level and fill all the available space, and they wouldn't stop you from running wires or making panel repairs down the road. You could add more beans as they settle out, too. I think it might take a half dozen bags to fill the gaps, but it seems doable. You'd want to seal around the closet area I think, or you could have an avalanche of beans if you ever pull the closet out. What do you think?

[Gina D.]

It is doubtful that anyone would pull the closet, or any other bit of furniture out of a Burro. It is molded and is part of the inside shell. Nothing is riveted on.. its basically all one piece. The only attachment points are on the floor, under a flange. They screw into the subfloor.

I thought Uhauls were the same? I haven't looked that close at any of them.

It could be done, I suppose, but it would take a lot of effort and skill, or a really big budget.

Andy, both my 13 and 17 foot Burros came with the factory insulation, so I had no need to find the way to do this, but I will tell you that I insulated where they didn't and it made a difference. This would be lining all the cubbies under the seats and back walls of the closet and kitchen cabinets with reflectix. Basically..anywhere it was only a single layer of glass. I know you don't like it, but it did work well. It was easy to do with a box knife and foil tape.

You may have to live with some gaps and just shove as much up into the walls as you can.. but some is better than none.

[Andy B]

Originally Posted by Matt in SV

I was in Orchard Supply today and they were selling bags of large bean bag pellets. Theirs are much bigger than the old tiny pellet size I'm familiar with. They're about 3/16" and about $12 for maybe 2 or 3 cubic feet. I wonder if you could seal the lower edge with expanding foam and then blow these things in through the roof fan access, or up from the bottom. They should find their own level and fill all the available space, and they wouldn't stop you from running wires or making panel repairs down the road. You could add more beans as they settle out, too. I think it might take a half dozen bags to fill the gaps, but it seems doable. You'd want to seal around the closet area I think, or you could have an avalanche of beans if you ever pull the closet out. What do you think?

Matt, that is an interesting idea! I had not thought about blown in insulation at all. In some places the gap between the shells is small, so maybe the smaller pellet size would work better. I wonder if static electricity would be an issue trying to blow them in. I will have to think about it some more, maybe get some R-value information.

Thanks,
Andy

[Andy B]

Originally Posted by Gina D.

Andy, both my 13 and 17 foot Burros came with the factory insulation, so I had no need to find the way to do this, but I will tell you that I insulated where they didn't and it made a difference. This would be lining all the cubbies under the seats and back walls of the closet and kitchen cabinets with reflectix. Basically..anywhere it was only a single layer of glass. I know you don't like it, but it did work well. It was easy to do with a box knife and foil tape.

You may have to live with some gaps and just shove as much up into the walls as you can.. but some is better than none.

Gina, Thanks for your Burro insulating experience. I am planning on using closed cell foam sheets on the outside walls behind the cabinets, etc. like you did with the Reflectix. Closed cell foam sheets should be easy to work with like Reflectix, it is good to hear that it makes a difference. When I remove the windows next spring I will find out if that gives me access to cavities at a higher level. Does anyone know if the Burro inner and outer shells are bonded together at the window openings? If the shells will come apart a bit with the windows out, I could slide some insulation into the cavities through the edges of the window openings.
Thanks,
Andy

[Matt in SV]

Originally Posted by Andy B

Matt, that is an interesting idea! I had not thought about blown in insulation at all. In some places the gap between the shells is small, so maybe the smaller pellet size would work better. I wonder if static electricity would be an issue trying to blow them in. I will have to think about it some more, maybe get some R-value information.

Thanks,
Andy

I found this:

The thermal resistance or R-value of polystyrene foam board depends on its density. They typically range from R-3.8 to R-5.0 per inch. Polystyrene loose-fill or bead insulation typically has a relatively lower R-value (around R-2.3 per inch) compared to the foam board.

Energy Savers: Polystyrene Insulation Materials.

I think the big benefit will be cutting convection currents in the wall. I am pretty sure mine's a draft magnet!

[Matt in SV]

Originally Posted by Gina D.

It is doubtful that anyone would pull the closet, or any other bit of furniture out of a Burro. It is molded and is part of the inside shell. Nothing is riveted on.. its basically all one piece. The only attachment points are on the floor, under a flange. They screw into the subfloor.

I thought Uhauls were the same? I haven't looked that close at any of them.

The U-hauls have the overhead cubbies glassed-in but the closets and cabinets have liners that come out - after 1984 according to the guide. I have had my closet out a couple times to pull wires. Makes a nice tub!

Regards,

Matt

[Andy B]

Matt, Thanks for the R-value information for the beads. One of the biggest advantages of blown in or foam in place insulation is the ability to get insulation into limited access locations. One reservation I have about the polystyrene beads is how they are such a pain if they get loose. They stick to everything when the air is dry. I have never used them for insulation, but it seems that if they were blown through a hose into the cavities that they would get a static charge and stick to the cavity walls rather than fill the far ends of the cavities. I guess after some time the static charge would drain and more beads could be blown in.

Andy

[Rusty01]

Andy, I am in agreement with Gina. I used Reflectix in my uninsulated Burro. It was difficult to get it into some spaces especially where the corners are on the roof. For the most part friction holds it in place and it has not moved since I installed it. When the sun is shining I can see two different spots about 1" x 8" where there is no coverage but I just consider them a beneficial air space. When I took my windows out I was surprised to see that only the top halves of the side window area had the fiberglass fused. I used this opportunity to jam the reflectix into and around the windows. As I recall, the glass in the front and back windows are not fused together making it easy to get the reflectix into those areas.
Like Gina, I used the reflectix over all of the exposed fiberglass on the cubby floors and behind cabinets. I used the 1/2 inch blue sleeping mats(from Wally) over that in the floor of the storage areas to hold the insulation and to minimize the vibration of the stuff riding on the top.
I used one layer of the blue closed cell underlayment for pergo type floors under the linoleum for insulation. This does not insulate very well but is probably better than nothing. I am now thinking of replacing that with spongy playroom jigsaw floor tiles and then placing the linoleum over that.
Without the Refectix insulation, the Burro would not hold the heat. With the insulation it heats very easily and stays warm. Like you I considered the different options and if I had to do it over I would do it the same way again. rb

[Andy B]

Originally Posted by Rusty Baker

Andy, I am in agreement with Gina. I used Reflectix in my uninsulated Burro. It was difficult to get it into some spaces especially where the corners are on the roof. For the most part friction holds it in place and it has not moved since I installed it. When the sun is shining I can see two different spots about 1" x 8" where there is no coverage but I just consider them a beneficial air space. When I took my windows out I was surprised to see that only the top halves of the side window area had the fiberglass fused. I used this opportunity to jam the reflectix into and around the windows. As I recall, the glass in the front and back windows are not fused together making it easy to get the reflectix into those areas.
Like Gina, I used the reflectix over all of the exposed fiberglass on the cubby floors and behind cabinets. I used the 1/2 inch blue sleeping mats(from Wally) over that in the floor of the storage areas to hold the insulation and to minimize the vibration of the stuff riding on the top.
I used one layer of the blue closed cell underlayment for pergo type floors under the linoleum for insulation. This does not insulate very well but is probably better than nothing. I am now thinking of replacing that with spongy playroom jigsaw floor tiles and then placing the linoleum over that.
Without the Refectix insulation, the Burro would not hold the heat. With the insulation it heats very easily and stays warm. Like you I considered the different options and if I had to do it over I would do it the same way again. rb

Thanks Rusty, That is just the type of information I was looking for! If I could get similar coverage using insulation sheets, with only a couple of 1"x8" areas missing insulation that would be great. I don't think that foam in place or blown in insulation could get better coverage than that!

I would most likely use foam sheets (sleeping mats or yoga mats or polyethelene sheets) instead of Reflectix. I would glue the foam to the outer walls and floor in the cabinets and cubbies and hopefully friction would hold it in the other areas. The foam sheets are cheaper per square foot and have a higher R-value than Reflectix although they do not have the radiant barrier. Reflectix might also be better at sliding into difficult to reach areas than the foam sheets would be.

Great information about access at the window areas, that should make a huge difference in getting insulation into some areas. The upper corners, with the compound curves seem like they would be the most difficult areas to reach.

Since the body of my Burro is off the frame for the floor replacement, I was thinking of putting a sheet of foam insulation between the floor and frame. A concern would be trapping moisture between the foam and the floor leading to floor rot. I was careful to seal the plywood floor well with fiberglass and resin but there are about 30 bolts that hold the floor to the frame and they are potential leakage areas.

Thanks for your experience and insight,
Andy