insulated transparent roof for screened porch ?

[cbc58]

is there such a thing? 

I'm designing a screened-in porch that I want to be able to extend the usability of into colder weather by installing plexi-glass panels and heating some way.... so I'm investigating if there is such a thing as an insulated transparent or semi-transparent material that could make up the roof.   I could do a regular roof but I'm trying to let in as much light in as possible. 

My camp will be in NH so it has to be sturdy to carry snow load.  Anyone heard of such a thing?  Tks.

[JRR]

You are facing a real, but interesting, challenge.

My thoughts:
1. Two clear panels ... separated with a small air space.
2. Fairly steep angle to help with snow.
3. Roll down thermal blanket shade ... to be used when the sun's not up or effective.

Wish you well.

[firefox]

I believe this is what you need. It is a little pricy, but not that bad. Be sure to close off the ends.
Bruce

http://www.usplastic.com/catalog/product.asp?catalog%5Fname=USPlastic&category%5Fname=68&product%5Fid=2620

  Polycarbonate Twinwall Panels
Excellent insulation, ribbed configuration of the multi-walled sheets traps air within the sheet, providing outstanding thermal insulation. Ideal for applications where specific light transmission is required. Impact strength 200 times greater than glass and 8 times greater than acrylic. 1/6 the weight of glass and 1/3 the weight of acrylic. Compliant with most international standards for flame resistance, at very high temperatures, material melts but flames do not spread. Will not crack or split when cut, sawn or drilled. Solar grade co-extruded layer protects the sheets against yellowing and surface wear from extended UV exposure. 100% recyclable. Maintains properties from -40° to 248° F. Minimum bend radius is 43.75" for cold formed arches. Other colors and sizes are available upon request.

[MountainDon]

It would be nice if they stated the R-value or U-factor for the material. 

[cbc58]

Thanks for the info.

[firefox]

Hi Don,
  I don't think it is very high unless you do something like make a header for it and fill it with argon.
Another company makes a 4 ply panel and it is about 3.5 R but it is very expensive. I think this stuff
is way better than plain glass, but unless you put some work into it I wouldn't expect too much.
The reason I would prefer this over the regular corrugated pannels is that I think it looks a lot better,
is a slicker surface for the snow to slide off, it doesn't yellow, and it is not affected by UV rays.

The stuff is pretty strong too, so if you put up two pannels to make a sanwidch and either filled the space between them
with argon, or just sealed it up tight with an airspace between them, I suspect you might get R 4 or 5,
but I am not sure it would be worth the effort. I don't have any experience with this so it could go either way.

Bruce

[firefox]

Here is another site with a slightly different product.
It is not completely transparant, but lets 70% of the light through.
It has the advantage of coming in rolls up to a 1000'
It is mostly targeted as green house covering.
This company also has all the connectors and caps to work with this stuff.

For a porch, I think it would work well. Assuming that you were going to have
an 8' roof by however long, You could get two pieces the appropriate length,
and they cut to order, you don't have to order 1000',
and all you would have to deal with is the center seal and the two ends.
I would do a lap joint in the middle, but a butt joint could be done with their connectors.
Bruce

http://www.farmwholesale.com/panels.php3

[Redoverfarm]

cbc58 not exactly sure what the demensions of your porch are going to be or the roof demensions but what about going with a standard Skylight or if room is permitting a couple. They have a good R value and are available as venting or non venting. I know they tend to be a little on the pricey side but there are good buys out there. Twice a year a builders auction is held near where I live. I took a neighbor and he ended up buying 8 Andersons for $125 a piece in cluding the flash kit(some companies this is an extra).   I have seen sun rooms done in this fashion with 2-4 in the same room  parrallel and it looked nice. The snow load would not be a factor. In fact I have 2 on the west side of my house(one directly over a woodstove  and there has been as much as 18" on them and it held for a long time until my woodstove heat finally melted them off.

They have made considerable improvements from the earlier bubble plastic ones and now they are insulated, sturdy and leakproof.

[cbc58]

Thanks.  I'm trying to investigate all my options for a 3 season porch and appreciate the info.  I like the translucent material if not for this application then something else I have in mind (outdoor bedroom)... plus it's relatively affordable.  I may wind up going with skylights if I can find them cheap enough.  The size of my porch will be 10x14 and will be on the south facing side.   Kind of playing around with a combo screened porch/w greenhouse type room design right now.