Hi Love the setting! From what you are describing, it sounds like you have a ventilation issue. A deck lower than 400mm off the ground needs to have ventilation just like the house. This typically means the sides are open (doesn't happen) and the spacing is around 5-6mm between boards. If you don't have this, the water that gets in cannot evaporate and will keep the ground and the underside of the deck moist, even with your drainage as it can pool in sections. This in turn means your deck is always wet. Once that happens, it is only a matter of time before fungus growth/soft rot etc occurs. We always excavate a low to the ground deck to ensure we have 400mm of clearance to the underside of the bearers. Another way is to ensure there is a moisture impermeable membrane across the ground (plastic) covered with gravel and graded down with vents placed all around. Cheers

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.

Well it's is simple, as we will now have concrete floor that get huge amount of winter sunlight in that main living room area our thermal mass figure went up. with the use of phase change material in the roof it to give a thermal mass effect but lot less weight. What it does is stores the energy/heat and transfers it back into room a night. You must realise that this is a very exposed site and we had to get min 6 star rating. Our insulation goes like this from roof down 1, R7 Rock wool batts 2. 90mm Phase change Material 3. to support pcm you have to use 12mm ply sheeting in place of plasterboard 4. Float concrete 5. Electric in slab heating 6. Precast tilt, but played down slabs Underslab 7. R7 Rock wool again 8. 75mm foam batts 9. Reflective foil 10. Box in around steel and make air tight as possible Also all the glass is double glazed, argon filled and thermal shield. We had all that minus pcm and failed because standard way of accessing doesn't have it in calulations. i had to go and show council a sample of the stuff an how it works. This is not cheap but we can just about say that room will sit at a constant 21 to 24 degrees all year around without need for air conditioning . Phase change article

Hi thanks for the reply, not sure about this one interesting concept. It just appeared that the moment I mention "timber" that I need full detail plans engineer certificates surveyors etc etc and comply with the Victorian building act which does not allow any exceptions. I just don't get the argument that they are concerned about "loading" over the easement surely a 100mm concrete slab is heavier than something like the above image. thanks Peter