Twin Wall Polycarbonate teardrop ? (Aquarium)

[tcolar]

I was wondering if it would be possible to build a very light TD out of Twin Wall Polycarbonate sheets.

This stuff is readealy available, as it's commonly used in for sunroom / greenhouses and not expensive.

http://www.greenhouses-etc.net/glazing/twinwall.htm
http://www.sunporch.com/Content.aspx?pageid=DIRoofGlazing#TDIRGStrong

Positives:
- It can't rot (plastic)
- They make most UV resistant (since it's used outdoor)
- It's lightweight, yet quite sturdy /impact resistant (~0.3# / sqft)
- It's a decent insulator on it's own (~R2)
- Readily available and not too expensive.
- It's somewhat flexible (2 to 3 ft radius)
- It's see through - good for the windows

Negatives:
- "Aquarium" teardrop : It's see through !
- Obviously would need to be painted - not sure what paint could "stick" to that ?
- Only "fairly" flexible, not tight curves.
- I'm thinking it could get brittel under some thermal conditions, although specs says it's not
- Bonding: what kind of "glue" could be used ?

Anybody tried using that material or why it would be a bad idea ?

[bobhenry]

Lexan makes a nice see thru roof...............







Hot as hell in the heat of summer ~~ Cold as hell in the winter

You can seal it with 100% silicone but "glue" ?????

predrill every hole oversize and reinforce with a rosette to distribute the force to prevent cracking. You can only snug it and let it float so it offers little skelatal reinforcement. In the spring and fall the roof is a wonderful thing and we do love it don't get me wrong but when it is 135 inside on a 88 degree day it gives a whole new meaning to solar gain. This is the reason we have a white aluminum roofed barn camper for summer and winter. I see absolutely no way to use it in the sidewalls unless you just float it over the completed wall as a veneer coating and trap it under the trim and exterior lights. In fact I attempted to do just that with eggbert.



I painted the subsiding flat black and then placed the smoked bronz lexan over it it looked like a 9 foot deep gloss coat.



Yep we still love it (spring and fall)

[bobhenry]

Kemlite makes a twin wall polypropelene panel with the pebble grain face on the show side that is reinforced internally it looks like single wall corragated cardboard ( they also make a double wall) THIS type of material would be my choice for a exterior wall material.

http://www.cranecomposites.com/BuildingProducts/kemply.asp

Shows an osb and a plywood substrate also

[tcolar]

And that place is a couple miles form my house
http://www.interstateplastics.com/aboutus.php

Now really thinking about making a trailer almost completely out of lexan/plastic

I actually think that should work, though probably would add a bit of wood framing/ribs at least to the front for piece of mind ... although they do have lexan rods / channels that could probably do as well

Need to take the calculator out and check on the math !

[michaelwpayton]

... Now really thinking about making a trailer almost completely out of lexan/plastic

I actually think that should work...

I'm sure that you COULD... but, I'm trying to figure out why you would? Sorry to barge in and demostrate my ignorance, but I'm just not "getting it."

[caseydog]

In Texas, we would call a clear roofed TD a portable oven.

CD

[tcolar]

Just cause it's different and sounds fun

What I'm thinking is that making it out of mostly lexan should be sturdy enough , yet VERY light, weather/mold proof and somewhat insulated ... and i could pass the electric wiring through the channels

Anyway it's just an idea at this point, but I really think its doable and will investigate it some more and try to calculate weight / strength implications.

[tcolar]

In Washington state we could call such a teardrop an amphibious, storm watching, retreat

Yes, they do advertise "storm watching" as a tourist / beach activity around here !

More seriously I would paint most of it, otherwise it would be an oven / greenhouse for sure.

[michaelwpayton]

Just cause it's different and sounds fun

What I'm thinking is that making it out of mostly lexan should be sturdy enough , yet VERY light, weather/mold proof and somewhat insulated ... and i could pass the electric wiring through the channels

Anyway it's just an idea at this point, but I really think its doable and will investigate it some more and try to calculate weight / strength implications.

Cool... I completely "get" being different and having fun Go for it!

[bobhenry]

Just cause it's different and sounds fun

What I'm thinking is that making it out of mostly lexan should be sturdy enough , yet VERY light, weather/mold proof and somewhat insulated ... and i could pass the electric wiring through the channels

Anyway it's just an idea at this point, but I really think its doable and will investigate it some more and try to calculate weight / strength implications.

Lexan is by no means light. I remember struggling with a 1/2 panel for the roof it is heavy.
I am curious as to your method of framing and need to see this build unfold so go for it and let us watch !!!

p.s. make all your bends in the heat of a really hot day and do it slow with ratchet straps. I took 3 days to train mine and each time I tightened I was waiting for the dreaded sound " CrAcK "!

[tcolar]

Actually you are right, the specs about weight I looked at yesterday seem to be off.

So it's not all that light, except the thinner ones (say 6mm twinwall) ... but at that thickness it's probably not very stiff at all.
I would use twin wall by the way, which I don't think is what you used.

Ho well, maybe not such as good idea, although i would still be interested to use some plastic materials ... i know some people have used coroplast.

[deceiver]

Polycarbonate. It's different from some of the things in this thread. It's the same material used to make the bubble windshields on fighter jets. It's very strong. Hard to break, weather proof, sunproof (uv type).

I used some corrugated ones that they sell in home depot to cover the top of a large purgola I made. The stuff was extremely thin and flexible but tough. About as thick as the cardboard cover on a phonebook but I was up there on my hands and knees screwing it into the joists on the roof. I weigh 250. It's been up there in four years of Maine weather and is exactly like when I bought it. It has a lifetime warranty. It was also extremely light as it was thin.

So, this stuff that is double walled and honeycombed must be nice. stronger than aluminum or wood or fiberglass I'd bet.

[tcolar]

Yes from the numbers I've seen it seems plenty strong, I've used some in remote controls planes so I know it's tough(crash), and I would think twin walls would be even stiffer.

I found some numbers about the weight:
- 6mm twin wall lexan : .3# / sqft - R value:1.6
- 8mm twin/triple wall lexan : .37# / sqft - R value:1.8
- 10mm twin wall lexan : .45# / sqft - R value: 1.79
- 16mm triple wall lexan : .55# / sqft - R value: 2.5

- ply 1/8 : 0.36# / sqft - R value: 0.15
- ply 1/4 : 0.78# / sqft - R value: 0.3
- ply 1/2: 1.56# / sqft - R value: 0.6

Fiberglass ? not sure I think ageless said it was ~ .3# /sqft when cured, i guess it can vary a lot.

But anyhow using just the twin wall lexan as the whole "wall" (no sandwiching) it would be very light, a 5.5'*10'*5.5' box would weight less than 100#

The way I see it is make the full "box" out of it (twin wall everywhere, except base/floor being just a flat sheet), all bonded together using special lexan solvent, and then probably all the edges covered with fiberglass for piece of mind.

Now a plastic "box" is quite sturdy on it's own, but regardless I would still make a "frame" inside the 'plastic' box, to provide some ribs/support, in particular from the roof and the "front" part which gets the wind pressure, and also because there needs to be something to "screw into" for attaching things inside the trailer (and the door).

That frame would be made of wood or maybe aluminum profile, and would be what gets bolted into the trailer frame - wouldn't want to bolt the plastic directly !

Anyway, still thinking about it.

One thing I'm wondering is what happen if it catches fire(if it can) ... wouldn't want to be in a shrinking melting platic box, that's for sure !
UPDATE: Apparently i will melt but not ignite /spread flames.

Here is a PDF with detailed (and quite impressive) specs:
http://www.sdplastics.com/sweet1.pdf

The only big minus is that it can't be bent in tight curves, although in my case my trailer is quite squarish so it might be ok. - also, I've read that it could be possible to get a tighter radius by heating it.

[kennyrayandersen]

I helped my daughter do a solar oven for a science fair project – she placed 3rd in the region (lots of data with flap angles sizes etc.). The inside of the over got over 250 deg F. It’s the first thing I thought of when I saw this thread. You would bake like a beef roast in that thing down south and maybe even up north.

I think you COULD do it (as someone else said), but it seems a bit silly to build the whole tear out of it. It’s not particularly easy to glue either, but I think you could work around that – it’s just the heat – did you see the amount of light that passes through the stuff on the chart of the first link you posted? Oo-ee!

How about if you just used it for some skylights or windows that let light in but mostly obscured the view (like water glass). I’m pretty sure you don’t want to make everything out of this stuff.

Just remember, just because you can do a thing, doesn’t mean that you should do that thing.

[tcolar]

Actually I like the material for it's insulation value, strength, and light weight, and really not because it's clear, if they made it opaque for cheaper I would use that

80% of Seattle's sun light is not much ! But, seriously, even here it could be an oven, that's why like I said I said I would paint most of it, except maybe for a few "windows"/skylight parts.

I talked to a friend today who actually owns a plastic company where they work with that stuff and build stuff out of it, he also is pretty knowledgeable about structural properties an so on.

The main thing of note is that he also said that, unlike PVC, Lexan does not bond very well .. he has a few solvent that work but nothing glues super good to Lexan.

So the way to go is to use fasteners (screws) as well as take advantage of existing U profile caps (plastic or aluminum).

I still think I'm gonna try this, over some alu or ply framing, it should be lightweight, original and rain/mold proof, worth a shot.

I'm not that worried about the "too hot" part, simply because that's only a property of the material being transparent ...some opaque paint will fix that.

The only one thing left I need to figure out is the low bending radius, might have to reshape my trailer a little, even though it's already very cubic.