Some people don’t consider timber fencing to be sustainable, but much depends on where the timber comes from. Many fencing contractors like Eline Fencing Perth use pine that is grown especially for such needs, so it could be said to be a sustainable source. However, pine is a softwood; it will need to be painted regularly to keep the water out so it doesn’t rot.
If you are intent of having a timber fence, there are other places to source the timber from apart from what the contractor offers. Here are a few examples.