There are two honest ways to handle a fall, and they look different when finished. **Raked construction** runs the top line parallel to the ground: cleaner to look at, no gaps underneath, and the usual choice where the grade is steady. **Stepped construction** keeps each panel level and drops it at every post: better on sharp or irregular falls, with the underside of each step closed off where security or animal containment matters. The third detail sits underneath both — a **contour-following bottom wire**, tensioned tight to grade so nothing gets under the line on a wash-out. Which of these your boundary needs is a site decision, and the finished appearance differs enough that it is worth seeing an example of each before you choose.
Established trees change the method, not just the price. Where a boundary runs through mature vegetation, posts get offset around trunks and holes get hand-excavated near significant root zones rather than augered blind. Constant leaf litter and shade-side moisture also push the coating decision: galvanised is the workhorse, and PVC-coated mesh copes better where damp organic matter sits against the base of a fence for most of the year. Any tree that genuinely cannot be worked around is a conversation to have at quote stage rather than on installation day — and whether a particular tree is protected is a question for the City of Moreton Bay about your address, not something a fencing contractor can rule on.
What actually goes wrong is the bottom of the fence. Height gets specified, mesh gets specified, and the bottom edge is left as whatever the installer normally orders. On a fall that is where the fence fails: a gap under the bottom rail that a dog, a wallaby or a person can get through, on ground that is washing out a little further every wet season. Treat the bottom detail as its own line on the quote and it stops being an afterthought.