Pull apart a failed timber fence and the story is almost always identical. The palings are fine, the rails are fine, and the posts have turned to soft fibre in a narrow band right where they enter the ground.
That band is where oxygen, moisture and soil meet. Understanding it tells you exactly how to make the next fence last longer.
The cause: the soil line, not the soil
Timber buried deep in wet clay actually decays slowly, because there is little oxygen down there. Timber in the open air stays dry. The zone that kills posts is the transition between the two, where the wood is damp and still has air around it.
That is why a post can look perfect above the ground and snap at your feet when you lean on it.
What makes it worse
Concrete footings poured level with or below the surrounding soil create a bowl that holds water against the post. Garden beds and mulch banked up against the fence do the same thing, all year round.
Treated pine posts rated for above ground use rather than in ground use are another common cause. The treatment level matters more than the species.
Footings that trap water instead of shedding it
Soil, mulch or turf built up against the post
Sprinklers hitting the fence line
Wrong treatment rating for in ground use
How a rotted post gets fixed properly
The palings and rails around the post are released, the old post and its footing are dug out, a new post is set plumb in fresh concrete, and the panel is refixed once the concrete has set enough to take load.
Cutting the rotted section off and bolting a stub or spur to the remainder is a short term patch. It works for a season or two and then the joint moves.
The upgrades that actually prevent it
Galvanised steel posts under a timber paling fence remove the failure point entirely. The palings stay timber so the fence still looks the same from the street, and the part in the ground no longer rots.
If you stay with timber, ask for in ground rated posts, a concrete footing crowned above the soil so water runs away from the timber, and a gravel base under the post for drainage.
Is it worth upgrading mid job
On a full replacement, steel posts add a modest amount per metre and often add five to ten years of service. On a repair where only a few posts are being reset, matching the existing posts usually makes more sense.
How long do timber fence posts last in Melbourne? In ground rated hardwood or treated posts generally give 15 to 20 years. Wet, poorly drained ground or soil banked against the post can cut that to under 10.
Can you replace a fence post without removing the fence? Yes. The panel is released around the post, the post and footing come out, a new post goes in, and the panel is refixed. It is a standard repair.
Are steel fence posts better than timber? For longevity, yes. Galvanised steel posts do not rot at the soil line, which is where timber fences fail. They cost a little more per metre.
Should concrete cover the top of the footing? The footing should be crowned above the surrounding soil so water runs away from the post rather than pooling around it.
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