Where is north in this photo? It looks to me as though the area in question is fairly shaded so a lot of the above options wont work if the area is on the southern side of the home, especially because of the winter shade. The space gets afternoon sun - in summer or winter? There are shadows from trees - are these deciduous or evergreen? Clay can vary enormously from being plasticine like to clay with rocks or stones in it. This will have an enormous bearing on the plants that you can use, precluding plants like westringias that require very good drainage. A plant that is as tough as old boots that will grow in both sun and shade [with some sunlight during the day] is Buxus microphylla var japonica varieties, while Aucuba japonica [Gold dust plant] or even some of the native lomandra grasses would work well. The first two can be grown as a hedge with the latter choosing a variety that you like [ there are so many], but have the plants all the same - don't mix them up. These will all grow in some shade, will grow in clay as well if it isn't too poorly drained. It does appear as though the area is sloping ever so slightly away from the house which is good. But I would steer clear of paving - unless its needed for access etc, it will look patchy and pointless - use plants instead to make your picture - its far more sustainable. Alison

if you can't install a permenant fence on the boundary and you can't plant into the paving, what about try some long narrow pots standing parallel to the back of the little hedge, fill them with a layer of pebbles for drainage, a layer of soil to plant some potato vine or similar and use the pots as support for panels of framed lightweight lattice to make a tall fence inside your garden, not on the boundary, a mastching gate across the steps and the porch should screen out all the neighbours...instant screen from your side and removeable if/when needed

im also in adelaide and trying to work out what exactl defines ”semi-detached”. is the roof shared between two dwellings or do they look like two separate houses with just a shared wall? also, does the shared wall go all the way along rhe entire length of the house or do they just share the wall between garages?

Not sure how it would go in Brisbane but what about trying a conifer? They grow fast and very tall. You can shape them or leave them natural. They are plain and certainly not tropical. Maybe speak to a local nursery and find out if they would grow in the sub-tropical climate of Brisbane first, as they are usually in colder climates (Sydney and south). Leightons Green Conifer – Leyland Cypress http://www.evergreengrowers.com.au/shop/hedging-screening/leightons-green-conifer-leyland-cypress/ Your quite limited if there's not enough sun and you dont use bamboo or tropical plants. Many other screening plants or hedges wont get tall enough for that space and climate. I hope you find something.