How to Tell If Your Fence Posts Are Rotting

The posts are the skeleton of your fence. When they rot, the whole fence follows — leaning, sagging, and eventually falling over. Catching post rot early can save you thousands, because a post can often be replaced before the entire section collapses. Here is how to spot it before it is too late.

Why Posts Rot First

Your fence posts sit in the ground, buried in concrete or dirt, in constant contact with moisture and soil. Even rot-resistant woods like redwood and cedar eventually break down at the soil line — the point where the post meets the earth. This is where almost all post rot begins, because it stays damp and never fully dries out.

The Warning Signs

• Soft, spongy wood at the base — push a screwdriver into the post near ground level. If it sinks in easily, the wood is rotting.
• Dark discoloration or mold — black, gray, or green staining around the bottom foot of the post is a clear sign of moisture damage.
• A leaning fence — if a section is tilting, the posts are almost always the cause, even if they look fine from above.
• Cracks or splitting — vertical splits let water in and speed up internal decay.
• Loose or wobbly posts — grab the top of the post and shake it. Any movement means the buried portion is compromised.

Repair vs Replace

One or two rotting posts can usually be replaced without rebuilding the entire fence. We dig out the old post, set a new one in fresh concrete, and reattach the panels — often in a single day. This is far cheaper than a full replacement and can add years to the life of the rest of the fence.

However, if more than a third of your posts show signs of rot, or the fence is already over 15 to 20 years old, it is usually smarter to replace the whole thing. Patching rotten posts on an aging fence is like fixing one leg of a wobbly chair — you will be back again next season.

How to Prevent Post Rot in the First Place

• Set posts in concrete with the concrete crowned so water runs away from the post, not toward it.
• Keep soil and mulch away from the base — anything that holds moisture against the post accelerates rot.
• Redirect sprinklers so they are not soaking the base of your fence daily.
• Use proper gravel drainage at the bottom of each post hole for better water flow.

When to Call a Pro

If you have spotted any of these signs, do not wait. A leaning fence gets worse fast, especially during the winter rains. We offer free inspections and can tell you honestly whether a repair or a replacement makes more sense for your specific fence.