Hi, why don't you have a think about installing composite decking which will allow you to be level with the door sill without the worry of run-off into the house due to the 5mm gap between the boards. Composite doesn't required coating so the maintenance issues are significantly less, just a hose down and sweep or mop with water. You would still need to excavate approx. 250mm below the finished deck level to allow for the sub-frame but if you use treated pine framing with, either H4 stumps in concrete, or galvanised stirrups to anchor the framing into the soil. Check with your local decking pro for further advice and brand options. Generally, the USA made composites like Trex or Timbertech are better quality and the concealed fixing systems are easy to install. Your soil type may be the only issue with water, ie clay which retains water, or sand which tends to drain more quickly. Good luck

We used spotted gum for our decking and love it! We got it for $4.25 linear metre from Masters (any lengths that were inferior they were happy to replace). Our deck was built next to our near-white pavers so merbau was out of the question due to its leaching (plus we also were wanting an eco-friendly local hardwood if possible).

The vergola option with louvres is very expensive but also very effective as it provides so much flexibility in all types of weather. If you are outdoor people then this may be worth the cost. Coming down in cost, a climber over a pergola is also a good option depending on where you live. In a cool climate make sure the climber drops its leaves early enough so the late autumn and early winter sun comes through. Conversely, if you're in a warm/hot climate then the longer the leaves stay on the better. Some deciduous climber and trees lose their leaves quite late. Awnings are also very flexible but may not allow wet weather usage. Of course this depends on the type and size of awning. Oops, I just noticed this was originally posted in 2014. I hope you've sorted it out by now.

Spotted gum for sure, merbau is blar... no grain or aesthetic appeal whatsoever. You have to use a stain so it does not fade but make sure you don't buy it at Bunnings because they do not stock any product that is worth putting on any timber. The two decks are Organoil in red stain and the railing on them is livos Alis in light teak. I use the livos on my own timber work but it is expensive. All this timber has been in the full elements for well over 10 years.