I have miles of decking at two houses. All timber when put in the Australian sun will suffer. When building our beach house we decided to go for Spotted Gum and let it grey. Why fight it? We applied Cutek, and will on a regular basis. At our main house we have lots of Merabu or Quilla. Will not grey the same, and leaches lots of red stain. Cheap, but would not use again. What ever you use, use a good quality oil that seeps deep into the wood not a traditional stain/or top finishing product.

What kind of trees so you have? They seem to dominate the space - the shade is probably nice in summer, but does it mean you can't grow anything else? To me, everything at the moment is either tree high or ground level - you need some plants at different levels, arranged to draw the eye around things. If the trellis is strong enough, consider a vertical garden of many different pots there - possibly not arranged in symmetrical rows. Or ditch the trellis and buy one of the vertical garden systems/frames from the big hardware stores. You can either go with decorative flowers, useful small edibles (herbs, strawberries, spring onions, lettuce etc) or a mix of both . . . In front of the window, a big planter box or a three or more different pots of various heights - maybe a big strelitzia (they're hardy and colourful) with lavender or cordylines . . . (Lavender always attracts a LOT of bees through summer - might not be the best thing for your little helper!) If you use the chiminea a lot, well, then it stays, but if not - consider gumtree or ebay, and if possible constructing a rockery-type bed around the base of the tree, with natives like lomandra or blue flax-lilies or, if you prefer exotics, things like hellebores and cliveas (my mum loved her hellebores) . . . might even be possible to squeeze them in along the back fence and keep the chiminea . . . But I would think about removing some of the astroturf (presumably on concrete?) and allowing plants to grow down into the ground. I don't think the bed itself should be all at ground level - a rockery, with some decent-sized rocks (half a metre or more), will break up the levels.

Hi hi North West, can you run your ducting in ceilings or floors? Thx

Houzz, this needs moving to design dilemmas.