I want a cover that will give protection from rain in the winter, and sun in the summer without being too dark. After weeks of research I'm not sure such a thing exists. The options I have found are metal - which I think will be too dark. Solar gray polycarbonate - we put some samples up and like the look but feel that it doesn't cast enough shade, I still feel like I need a hat or sunglasses sitting underneath it. Solar control silver polycarbonate is another option, but because it is so new I haven't found any testimonials from people who have used it and liked it, and the few pictures I was able to find of it in use made me think I wouldn't like the way it looked. We have a color sample coming in the mail, but I'm not sure that a 2" square will give me a good enough idea.

I'm also starting to think that something that gives enough shade during the heat of summer might be too dark during the gloom of winter, and maybe clear or gray poly with a shade sail that can be put up and taken down might be the best option.

Any thoughts or advice will be greatly appreciated!

The side that has the poly samples on it is south facing. We were aiming for a structure that would let in plenty of light and preserve the view of our oak trees, while blocking the summer sun from about 2-5pm when it shines on the western wall of the house and makes it hot inside.

I question the size of those support posts--those are not just 2x4's are they? How are they secured to the deck?

Now that I know about the oak, I can see it's shadow on the ground. That oak is probably going to shade the interior of the patio during midday during the winter. Of course, you have lived there so you would be better able to make that determination. The house is probably going to block most of the morning light and it looks like you will get quite a bit of light during the latter part of the day.

Here's the view from the deck, looking out at the trees:

I like that you can still see the trees a bit with the grey poly, it provides some shelter without making it feel too closed in. After living with that for a while that it's hard to choose a completely opaque option. I'm sure insulation and shingles would keep it cooler, I'm just not sure we need to go that far. It's really not that hot, considering all the shade we get from other sources. The biggest problem was with 3-4 hours of afternoon sun on the wall of the house (and no a/c) it was getting up to the mid eighties inside, which is too hot for me. My main concern is keeping the house cooler in the summer, but also having a comfortable space in the gloom of winter. And winters can be pretty gloomy here, our neighbors to the south have some very tall evergreen trees that cast a lot of shade on our property. The oaks drop their leaves and look gorgeous, I love the bare, mossy branches and the fascinating shadows they cast.

I don't think we'll grow any vines on the structure, I'll have some on trellises at a safe distance where they won't be able to attach and do any damage.

The support posts are 4x4's on concrete piers, I'm not sure how they attached them to the deck, maybe lag bolts. My bf and his buddy spent a day figuring out how to make it sturdy enough for them to be happy, but high enough for me to be happy. I wanted them to preserve my view of the oaks, and I think they did a great job.

I think my main issue is that I like the look of the grey poly best, I just don't like that I have to squint my eyes when I'm underneath it. I wish they still made multiple options for light diffusion, they used to have 50%, 35%, and 20%, now all anybody has is 35%. A friend came up with the best solution - something that can change from darker to lighter depending on light conditions like those transitions sunglasses. That would be awesome.

Still waiting for those samples to come in the mail, until then I don't have to make a decision... I never thought that choosing the covering material would be the most difficult part of the project.

Thanks again!

Ahh I see you have oaks that actually drop their leaves in the winter unlike me.

In the morning, when it's foggy, I go out there and think: 'there's no way we can put an opaque roof out here.' But by the time the sun comes out and I'm hovering in the small amount of full shade I start to think: 'I don't want to have to wear a hat on my covered deck!'

The color samples still haven't arrived, we might have to call the rep and ask a second time for them to be sent. Also, with continuing research I've started to come across some warnings against Suntuf poly, people who say it's a cheap knockoff and Lexan is much better, but Lexan is also harder to source. *sigh*

So anyways, I'll just keep thinking about it and maybe in a month or two I'll be able to post pics of the finished product ;oP

Thanks for all your thoughts and advice!

Lexan is the brand name for GE's line of polycarbonate thermoplastics, and is not any specific roofing product (there are also many other manufacturers of polycarbonate besides Lexan, just as there are other manufacturers of facial tissue besides Kleenex. They are just as good and often less expensive).
The first picture below shows some of the structural roofing panels manufactured by Lexan (they make hundreds of different products). The webbing between the plys functions much like a miniature truss. This is what makes them structural. The bottom picture shows another one of their products, clear polycarbonate sheet. It is nonstructural, and using something like that is probably penny-wise and pound-foolish since you're going to need much beefier framing to support it, both to keep it from sagging and to prevent wind-shear damage.

Naturally, homeowners are free to use whatever they like, but I would seriously question the building credentials of a person who advocated the use of nonstructural panels in a situation where structural panels are called for. Remember...it's the stingy man who pays the most in the long haul.