6mm solid clear polycarbonate roof

It was never said that it would help with AMBIENT temperature. Rather that what would be under it might not get as hot as it would sitting out in direct sunlight. I will test this out after it’s installed, though. As I am curious. lol.

I have decided to go with the 10mm twin wall as it will allow for the wider raft space and I want to have some vines growing underneath so it won’t be on full display.

Hmmm, I’ll have to take your inputs into consideration, I don’t want them to be sagging.

Do you guys have high humidity? I feel like it makes things worse. My family lives in California, they have dry heat and the 112F is so much more tolerable without humidity.

I used 10mm twin wall with 600 centres for the beams but the twin wall was 1200 wide so I only needed half the amount of the snapdown glazing bars just at the 1200mm joins, the middle 600 on the beams was fixed with the buttons https://www.thepolycarbonatestore.co.uk/10mm-white-fixing-buttons
The glazing bar is screwed to the wood beam.
Something I have noticed is that I get green alge on it even though it is not in a shaded area. I wonder if clear 6mm or whatever wold help stop it as it is smoother as the 10mm twin wall has ridges giving it something to get hold of.
The clear poly carb does look very good though - like glass but is much more expensive than twin wall. But for me it was a massive upgrade from the corrugated clear sheet I used to have.

I used the clear poly but still get the algae.
@Honestly70 sounds like you are using a counter batten type structure (ie battens on rafters) where I fitted the poly directly onto rafters.
Something like this I presume:
https://www.roofingmegastore.co.uk/blog/how-thick-should-my-polycarbonate-sheets-be.html
If the battens are decently sized and at reasonable centres then it should be ok - check with suppliers.

@aveatry, agreed, I consider it an upgrade as well. it is a 2000USD price difference between 10mm twin wall AND 6mm clear, Since I’m doing my deck as well, I need to compromise. I was between the aluminum or clear u/h channels so I’ll try the clear and see how that works out.

@Sam, yes, that is similar to the set up I have now, but more sparse. There will be 4ft (1219mm) spaced rafters and the place selling the poly sheets recommends cross support every 31in(787mm). Will see what the installers think once the material is here.

Appreciate everyone’s input, it has been helpful in making decisions.