Pergola Correct Fall

Hi there I am wanting to help my dad build a pergola over his deck for the summer, There are posts going up a good 3 m up from the deck already, I think the owner before was planning on building a pergola but ran out of time, the old man wants to run rafters and have that clear lite stuff over the top so we can still sit out there when its raining.

My questions as I am pretty new at it.

What is the correct fall for water, the distance is about 3m from the house to the end of the deck?

Also to fix a stringer to the house at the top above the sliding door, what is the right way to do this, eg. weatherproofing etc, its a weatherboard house?

thanks in advance.


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