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

Merbau is an imported hardwood apparently from Indonesian 'sustainable forest's'.... I'd stick with local hardwood's as you will know well truly that they are 'sustainable forest's'..... It's only a few bob more so may as well support aussie job's as well as the environmental factor's such as transportation. Tallowwood is a good outdoor timber but so is spotted gum and ironbark. Just come down to cost for me as all aussie timber is world standard quality. You could put fibre cement sheet on top of rafters then colorbond over. Lot of options to choose from, plywood, t&g timber as well as the fibre cement sheet. Depend's on the 'look' you're after, budget, etc.

Hi friendly Kim. I've just looked at your profile to see if I could find your photos. I noticed you have them on a new post. I now understand, you already have a full alfresco area under the main roof, and vertical sun blinds, and also have noticed your fan, as you mentioned. The roof extractor fan may help remove the heat. I was also thinking if you had some tall lush plants along the side where the pull down blinds are. This would stop the sun, but allow the air through. But, sometimes we just have to move inside. This is why solar passive orientation of our new homes is so important. Hope you find a solution.

@jstirl91 the pavers in the 2nd photo look like they would work well with your house as the house is also a weatherboard & you're installing a similar roof. Castlemane slate could also be nice & comes in similar colour tones to the pavers in the 2nd photo 🙂