[BadWolf]

I’ve been looking at ways to reduce weight and improve R-Value in my build.

I came across the polyethene used in green house exterior walls(tech sheet attached), which is close to the same price as the 1/4 birch. Where it gets interesting is the 0.16lbs per sq ft weight and 2.1 R-Value. Also it comes in sheets or rolls, i know the roll option would reduce waste and possibly even cost.

My walls and ceiling are currently ~300sqft of ¼ birch plywood, which at ~0.9lbs per sq ft. I’ve got ~275lbs of dead weight there, with an R-Value of ~0.3.

The other major perk would be moisture, or lack thereof. The poly won’t absorb any water/humidity or rot over time. My walls are covered in fabric/stick on wall paper so I don’t have to worry about the color.

Has anyone used anything like this on a large scale in their builds?

 

[orton]

I used something similar for the ceiling and the shower walls. 8mm Macrolux polycarbonate.

Ceiling | Orton Travel Transit (ortontransit.info)

Worked well for the ceiling. The issue is the mounting screws require a fender washer or the material compresses at the bolt location. Did not like the end result on the shower walls so removed it and replaced it with painted plywood. Did not like the color or the large fender washers. Was excellent choice for a white ceiling. Since it was somewhat translucent, I added a thin layer of white Insulate on top of the panel. Without the Thinsulate a person could add LED light strips to have the whole ceiling illuminated.

Get a sample from the vender so you can determine how to bolt panel to the walls and what the joints would look like. I would not want to use it for wall coverings.due to what it would look like. The other issue is what the joint would look like where two panels meet. For the ceiling I made square plastic pins that fit in the panel holes to make the two panels height match. That worked very well but you can see the pins.

 

[joe.horton.jr]

I’ve been looking at ways to reduce weight and improve R-Value in my build.

I came across the polyethene used in green house exterior walls(tech sheet attached), which is close to the same price as the 1/4 birch. Where it gets interesting is the 0.16lbs per sq ft weight and 2.1 R-Value. Also it comes in sheets or rolls, i know the roll option would reduce waste and possibly even cost.

My walls and ceiling are currently ~300sqft of ¼ birch plywood, which at ~0.9lbs per sq ft. I’ve got ~275lbs of dead weight there, with an R-Value of ~0.3.

The other major perk would be moisture, or lack thereof. The poly won’t absorb any water/humidity or rot over time. My walls are covered in fabric/stick on wall paper so I don’t have to worry about the color.

Has anyone used anything like this on a large scale in their builds?

Look at Coroplast at the orange Big Box store. A friend used that in her Transit conversion for any interior surface covering. Looks like $30.5 vs $44.5 and 10 lbs vs 29 lbs for 4x8 sheets.

 

[MMc45414]

I think if you like the Solex idea but it doesn't need to be translucent and you will cover it, might just be simple corrugated plastic sheet. My wife runs a small large format (intentional oxymoron... ) print shop and they use the stuff extensively. This is the stuff those crappy yard signs are made from, but it is also available in thicker thicknesses:

Another good aspect could be is that it is a common product that is probably availably locally no matter where you live, to avoid shipping 4x8 sheets. If you look up a local distributor that sells plastic sheets the lingo will be "CoroPlast".

There is also a nice tool called a flute cutter, that makes it easy to make rip cuts in line with the estrusion, including cutting only one side so you can bend and shape it.

And there is an alternative product called Alumacore, that adds a thin veneer of aluminum to both side. Will be stronger but will dent easily.

 

[jcbarr23]

In our town after local elections, the campaigns work together to pick up the signs. Usually, the losing side never wants theirs back and there'll be a big pile for a couple of weeks available for anyone who wants before they go to the landfill (I don't think they are recyclable). Sometimes artists or teachers will collect for projects as well. If you're still building in November, worth asking around what folks are doing with those eyesores!

 

[MMc45414]

Sometimes artists or teachers will collect for projects as well.

And target shooters..

 

[AzB]

And target shooters..

They make great target stands!

 

[kenryan]

When considering alternatives, look closely at the R-value. The only way to achieve R-values like that in a thin material is by achieving a near vacuum. Any thin plastic product that does not somehow incorporate the benefits of a vacuum is going to have negligible insulating value.

 

[njvagabond]

Solex is a brand name for corrugated polyethylene (PE)
Coroplast is a brand name for corrugated polypropylene (PP) (has become a genericized trademark)
The Macrolux is a brand name for polycarbonate. Multiwall (in this case) is their twinwall product
FWIW - these material are actually extruded, not a laminate of corrugated sheet(s) like corrugated fiberboard (AKA corrugated cardboard ) inferred by the naming in the first two cases.

The Solex literature compares their product to twinwall polycarbonate but not to the hdpe corrugate. I suspect the R valuse for those two might be very similar. I'd also guess that they don't make the call out because maybe PP is not typically use in greenhouse applications?? The PP in the comparison chart is just thin sheeting. The specs get a lot into light transmission, so that seem to be one of the reasons for PE in the greenhouse application. UV stability might be another issue.

l thing PE may be it is more flexible than PP which would be good for the semi-circular framed greenhouses that the Solex is often shown on. It comes in rolls whereas the PP comes in sheets. If this is the case it would seem that the PP would be better for paneling a van. Maybe the PE would be good for the front ceiling in a HR or as a stiffener in window cover or to sheath a cool rounded end cabinet. Would be interesting to find some for a touch test.

Here is a site with a wide variety of corrugated plastic materials.Corrugated Plastic sheets, panels, pads, rolls, Corrugated plastic sheeting, 2mm 3mm 4mm 6mm 8mm 10mm corrugated plastic sheeting, bins, single face corrugated plastic white clear plastic corrugated sheets
The physical location is really close to me. I really should go there one day to see what material they may actually stock in this location.

 

[perchancetodream]

I used 1/8" Baltic Birch. So half the weight. Half the insulation value too, but really...the panel R is insignificant relative to the foam and 3M SM-600 batting behind it.

 

[surly Bill]

I like the idea of translucent extruded plastics as a wall, but personally I would go with 1/8-1/4" melamine coated MDF for the durability.
But, if reduced weight is the goal, the plastics are great, won't rot (but may "dry out" and crack), and the captured air inside provides good insulation.

You can use the translucence by installing LED light strips around the edges, making the whole panel glow (use white backer or paint).
Or you can adhere a fabric or vinyl to the cab side to make it pretty. That might get it back to the weight of 1/4" ply, though. BUT, it would have the superior properties of the plastic.

jcbarr; I was going to go around and remove the big 4x8' campaign coroplast signs to use for projects, but forgot. Many were up for literally a month or more after the elections, some of the little 1x2' signs are STILL up. Good call on saving these for projects rather than having them go to the dump to not decompose forever.

 

[rustythorn]

another option is Corrugated FRP it uses the same 'tech' of dead air spaces so it should also have a slightly higher r-value than a solid sheet but i doubt anyone has put any effort into measuring its insulation values. regular plastic is around 1.5 r-value and since we are are talking about 1/8 - 1/4" thick sheets that would be a total insulation value of 0.1875 to 0.375. with corrugated air gaps Solexx is listing 2.1 - 2.3 so the total insulation would be 0.289370079 to 0.4527559055 so a maximum gain of 0.077755905 that is not much relatively if your van has an total r-value of 5-10. frp also has a higher strength to weight ratio and i imagine the corrugated would be even higher.

while i'm planning on using some kind of plastic sheeting in my van, there are some woods with the same r-values as plastic but are lighter for example cedar although it seems that bark has twice the r-value so you could make a very rustic van?

 

[Rolf]

1/4 wall panels is thick and sturdy enough to attach small shelving…clothing hooks and such and
additional support from ceiling mounted L Track to beams or solid furring mounted to beams via
rivet nuts…then you can just get very lite 1/8 veneer or what ever for ceiling…….I got 5 ply 1/4
for walls and it got really good screw retention hold… the cheap 3 ply at big box stores not so
much. Anyone shopping for quality ply , you will be surprised that the specialty lumber stores
will sell the high quality plywoods for not much more and sometimes less than the box stores
cheap stuff, maybe I got lucky but my local special lumber store sold the good stuff and was
in fact cheaper than the crappy Home Depot stuff.

 

[BadWolf]

Did not expect that many/quick responses.

@kenryan I do take the quoted R-Value with a gain of salt but should be at least a small improvement going from 0.3 to 2.0, its more of a bonus to me.

@orton Aesthetics don’t matter since I’m going to cover/wall paper it, and planned on the fender washers after handling it. If possible i was thinking i could cut 2 sides of a cell off and make a lip (L shape) and have a little overlap.

So I’ve been looking at all 3 main options in the responses, and been able to play with the polycarbonate and corrugated plastic in the stores.

Solexx/polyethene, I’ve reached out to Solexx to try and find it locally to see if its stronger than the polycarbonate. The roll idea of it I really like, if I plan on swapping all out at once.

Macrolux/polycarbonate I can get at Lowes in 4x8 feet at ~$50 a sheet and seem viable

Coroplast/polypropylene/corrugated plastic sheet – when I found it in Lowes, it doesn’t seem strong enough and will retain damage/dents more easily. Plus, it’s a little harder to find it in large format

@MMc45414 / @rustythorn I like the ideas of the Alumacore /Corrugated FRP, until I saw the prices, for a 4x8ft sheet.

@perchancetodream Where did you source your 1/8" birch, 1/4 is the thinnest i can find.

 

[njvagabond]

I keep meaning to buy a sheet of 5mm Revolution plywood underlayment to put on a wall of the van to see how stable it is (it has 5 plys) , also how it takes paint/stain. They don't call out a species, but this document from Columbia wood products, the distributor of the product, calls it out as Chinese grown poplar, so maybe lower density than Russian grown birch (good luck finding Baltic Birch from Finland). My guess is that it is not as strong as the birch. Unlike most all of the Baltic birch available, the Revolution ply did not appear to have any patches/plugs in the face veneer. The face veneer has a very uniform grain that I personally like for the scale of a van.

Plastic panels would be more stable than wood and won't absorb and emit (? word) water. Wood can be seale pretty well. I wonder if the end of corrugated plastic should be sealed to avoid condensation in the flutes.

 

[BadWolf]

@njvagabond sealing the corrugated ends shouldn’t be too hard. A simple can of spray foam might work. It just would be tedious, but would add a sealed air gap. I wonder how elevation changes would affect it.

 

[njvagabond]

Where did you source your 1/8" birch, 1/4 is the thinnest i can find.

I BB for my floor on a roadtrip when passing through Toledo OH at Toledo plywood. Kinda far from CO but on route to some great places in the East.

 

[njvagabond]

@njvagabond sealing the corrugated ends shouldn’t be too hard. A simple can of spray foam might work. It just would be tedious, but would add a sealed air gap. I wonder how elevation changes would affect it.

Good point
It is low surface energy so most stuff does not stick to it, but spray foam does stick like stink. Might not be the best aesthetically although if you could control the fill of the channels (start long and cut down?) there are h-channels or you could do something with wood to cover it. You could also weld the ends shut?

wall paper it

First mention I have seen of this. Glad to know I am not alone. I was thinking of vinyl wallcovering. There is some good looking stuff. It might be good to use something more robust than wallpaper paste? But if you use something too strong, then it would be hard to remove if ever necessary. Any thoughts on that?

 

[natecostello]

I’ve been looking at ways to reduce weight and improve R-Value in my build.

I came across the polyethene used in green house exterior walls(tech sheet attached), which is close to the same price as the 1/4 birch. Where it gets interesting is the 0.16lbs per sq ft weight and 2.1 R-Value. Also it comes in sheets or rolls, i know the roll option would reduce waste and possibly even cost.

My walls and ceiling are currently ~300sqft of ¼ birch plywood, which at ~0.9lbs per sq ft. I’ve got ~275lbs of dead weight there, with an R-Value of ~0.3.

The other major perk would be moisture, or lack thereof. The poly won’t absorb any water/humidity or rot over time. My walls are covered in fabric/stick on wall paper so I don’t have to worry about the color.

Has anyone used anything like this on a large scale in their builds?

We looked at a few corrugated plastics during our design phase for all the reasons you mentioned. The all the samples we tested were to easy to crease. We finally settled on expanded PVC sheet which is about 80% the weight of BB, but doesn't require any treatment (painting/urethaning). We had our hearts set on PennLight (about 50% weight of BB) material, but couldn't source it to meet our build deadline. That's what I go with if I had to start over.

EDIT: If you do go with a plastic, make sure to mind the specific type and surface energy if you are going to adhere anything to it.

 

[orton]

I tried 1/8" plywood for a wall covering and found it to be too flexible. Changed to 1/4".

I did not seal the ends of the 8mm twinwall Macrolux polycarbonate I used for a ceiling and have not noticed any issues.