Spend the minimum on structural changes. However, it sounds like no fence could raise buyer objections and invite discounting. The deck can be added, or not, by the new owners who will want to make their mark on the house. Spend time and energy styling your interior for 'fall in love factor' that speaks to your ideal buyer. This diminishes objections every time!

Tiara60, Can't speak from a personal point as we are going to have concrete, but to go 80mtrs x 1.8m mtrs right around the house and of course us doing all the work like laying the rio screeding etc... is about $3,000 I think it sounds like allot but I know Merbau can be expensive, I'd certainly do some comparisons for your own peace of mind. Our daughter used Merbau, very dissapointed as the timber distorted over time, not to mention all the upkeep, that's why we've chosen to concrete our veranda's instead. Hubby and I are well over 50 and I wanted the least amount of maintenence possible, so aluminium windows and doors too, I still think it will look lovely. By the way, you mentioned ramp/walkway, try to avoid steps if you can, as a ramp only will always allow for pram or wheelchair access, we too have steps at the front of the home we are currently building and a ramp at the back of the home.

Hi Debra, I see you are trying to waterproof under the top deck and improve the area below for outdoor living and connection to your proposed pool. The problem is with timber upper deck and waterproofing is that to do the job properly will be what jbantick said. Even if you added a waterproof layer it will still collect not only water but dust & debris through the decking. The FC sheet eliminates this but will need tiling to look any good up there. The rain ingress from the side will also need to be addressed. Have you had a professional look at it and advise on method & the cost involved? It might be more cost effective to leave the under deck area as a transition to a separate pool pavilion if you have the room.

It seem like you have western sun on the back of the house due to the blinds in you patio photo. To combat this the new roof could be angled low on the west and high over the house as in a fly over roof. Maybe shade sail over the spa attached to the patio roof and lots of tropical plants. It is hard to guess from the photos but if you link the two areas with decking & add gardens surrounding it for shelter. Do you need a fence around the spa? Others have said that the composite decking is good and it won't rot like timber or at least is low maintenance for a wet area.