The law of averages dictates that out there are people who are - to a greater or lesser degree - planning their dream house designs based on how zombie-proof said houses may be.
I personally have been considering this sort of thing ever since, I saw the movie Jurassic Park and realised how easy it would be for velociraptors to smash their way into the family house through the huge windows which grace every room, and eat my entire family*.
There are some existing house designs that you could opt for without drawing the suspicions of the council or the concern of your neighbours, such as the classic 'Queenslander'.
The Queenslander could definitely be a strong contender as long as you had a way to destroy the staircase safely, made sure that you had access to water and enough food stockpiled or a safe way to exit and enter the house without making yourself a snack or inviting observant zombies or human raiders back into your home.
The height would give some peace of mind as long as the stability of the foundations was assured and fire wasn't too much of a risk**.
But personally I like the idea of thick strong walls on the ground***, surrounding you and protecting fertile soil where you can grow vegetables and keep animals to help sustain you.
For that reason my preference would be for a modified enclosed Roman villa-style building.
To make this design more zombie-proof you would of course minimise the windows on the outer wall of the structure, and make sure that those that remained were small-framed and high-set to allow light and air where appropriate but no physical ingress.
The main door would be heavy, outward opening (so that pressure applied from the outside wouldn't open it) and easy to bolt and bar with both a thick wooden outer door and a heavy metal lattice portcullis as an inner door. If the outer door is breached the portcullis should hold back intruders whilst allowing you to kill and reduce them, hopefully driving them back long enough to secure the outer perimeter if safe.
The walls would be thick, both for protection and to muffle the moans of the undead which would cause psychological distress over time.
The roofs would be broad and set up with water collection/storage and solar panels.
The central space would be set up to allow the growing of fruit and vegetables and the keeping of chickens for eggs and meat, and goats for milk if space and arrangements allow.
A well to complement the collected water would be a wonderful addition for peace of mind.
The four corners could be adapted to each host a high observation tower to let sentries keep an eye on how things were going, man radios if available and possibly communicate with other survivors by means of shining lights or using mirrors to flash Morse code messages, use weapons if needs be.
The plentiful rooms would allow multipurpose areas: sleeping areas that could be transformed to living areas during the day, food storage and preparation, laundry areas, work and manufacturing areas.
If practical underground rooms could be included and used for storage and would be more appropriate for peaceful and safe sleeping areas.
And I guess I would explain all of this to the council and my architect as an attempt to get on Grand Designs Australia and hope that they buy it and don't have me put away in a mental asylum.
I expect it'll help if I don't actually indicate where gun turrets should be mounted on the towers.
And all I need to do to make this a reality is get rich enough to build this place whilst also making time to learn how to manage a garden, keep livestock, preserve foods, shoot and maintain firearms and make sure that none of the people who I plan to invite to join me in my lovely villa are the type to crack, throw the gates open and go running screaming into a horde because they can't take it any more****.
*I was a pretty mercenary child. I had calculated my chances of being able to save anyone seeing as the velociraptors would have access to every part of the house simultaneously thanks to all the windows, realised they were so low as to be negligible and had decided that my best bet would be to scramble into the top of my built-in-robe shelves, try and kick my way into the roof-space and then lie their with my fingers crammed into my ears trying not to listen to the sounds of my family being rent asunder.
Velociraptors are a lot faster and smarter than zombies, what other options did I have?
**Honestly if zombies overrun Australia, a pressing concern along with being eaten alive would be the bushfires that would likely break out and sweep across the country unchecked, burning out survivors and foodstuffs but hopefully crisping the hell out of a large percentage of the undead at the same time.
***And not having to worry about a sea of the undead swaying and moaning below you as you slept, constantly dreaming of the floor giving way and dropping you into their waiting arms...
****Or the type who will decide the zombies are a judgement from God and that we either deserve this because we've brought it upon ourselves OR that the zombies will only eat the unrighteous and that this is a test.