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

Hey there - these stories may help you! Who's On Deck? [5 Hardwoods Suited to the Australian Climate[(https://www.houzz.com.au/magazine/whos-on-deck-5-hardwoods-suited-to-the-australian-climate-stsetivw-vs~45817061) is written by Josh from Harrison's Landscaping (so you know he knows what he's talking about!). Then there is also [How to Build the Best Deck to Suit Your Lifestyle[(https://www.houzz.com.au/magazine/how-to-build-the-best-deck-to-suit-your-lifestyle-stsetivw-vs~27270085). Hope this helps!

Both are exceptional. It would come down to costs at the end of the day rather than the species.

I have just gone through the same decision making process. I rejected the composites due to cost, scratching, smell, and how much heat they emit. I rejected merbau due to leaching of the tannins, unsustainable harvesting practices (despite what is preached), and the threat to orangutang habitats. I chose spotted gum for looks (more brown than red), reasonable cost, easy maintenance, and it is Australian grown and produced. There will be those who disagree with my decision, but at the end of the day I wanted a reasonably priced but attractive, durable, and low maintenance decking board. It takes longer to lay the hardwoods such as spotted gum as they have to be pre-drilled, but the total extra for a 5m x 5m deck was $1000 for labour / timber compared to merbau. A quick oil once a year is the only maintenance. Pinterest is a good resource for how they all look once down.