Screw pile foundation for patio.

[Onden]

Hello.
During my vacation, I plan to start building my sunroom.
As the title suggests, I have a question regarding the foundation.
I want to avoid using treated wood as much as possible; after this winter's sill replacement, I have a love-hate relationship with treated wood in general. And I work at a planing mill, so I have relatively good access to untreated lumber.

But to the question.
Shouldn't the outer support beams be treated since they are more exposed? The inner beams will be airy and under a roof in any case?
Or am I thinking wrong?
And should/can I encase them somehow for extra security? I should add that I will be building a small deck around the entire sunroom as well.

Suggestions/thoughts/opinions?

Best regards,
Andreas

 

[Kallebo]

As long as the wood is airy and has drainage, I don't think you need to use pressure-treated.

 

[vectrex]

Everything depends a lot on the exact design of the conservatory. But generally, if they will not have ground contact, I would use regular framing lumber.