A rotted fence post is the #1 cause of fence failure — and the most common repair request contractors receive. Per the AFA's Fence Installation School, post holes are the foundation of every fence. When that foundation fails, the fence leans, sags, and eventually falls.
The good news: you can fix or replace individual posts without tearing down the entire fence. Here are four methods, ranked from easiest to most involved.
Diagnosing the Problem
Before choosing a fix, diagnose the failure:
Rot at ground level (most common): The post is soft, crumbly, or visibly deteriorated where it meets the ground. The above-ground portion may still be solid. This happens because the wood-to-soil contact point traps moisture — exactly what the AFA's training addresses with proper concrete crowning and drainage.
Leaning post with solid wood: The concrete footing has shifted, cracked, or was too shallow. The post itself is fine, but it's not plumb. Common in areas with expansive clay soil — Houston, Dallas, and Atlanta.
Broken post above ground: Impact damage, severe wind, or a fallen tree. Usually requires full replacement.
Post loose in concrete: The post has pulled away from the concrete collar, rocking back and forth. This happens when the original hole was too wide, the concrete didn't bond, or freeze-thaw cycles separated the post from the footing.
Method 1: Steel Post Mender (Easiest)
A steel post mender is an E-shaped bracket that bolts to the existing post base and extends into the ground for support.
When to use: Post is rotted at ground level but solid above. Fence panels are still attached and in good condition.
Process:
- Dig out the soil around the rotted base, exposing 12–18 inches of the post
- Cut away the rotted section with a reciprocating saw
- Slide the steel post mender onto the remaining solid post
- Drive the mender's ground spike into the earth (or set in concrete for maximum strength)
- Bolt the mender to the post with lag screws
Pros: No fence disassembly. 30–60 minutes per post.
Cons: Only works if the above-ground post is solid. The mender is visible at ground level.
Cost: $20–$40 per mender + hardware. Professional: $100–$200 per post.
Method 2: Sistering (Adding a Support Post)
Bolt a new post alongside the damaged one — the new post takes over the structural role while the old post remains in place.
When to use: Post is leaning but not severely rotted. You want a quick stabilization without full replacement.
Process:
- Set a new post in concrete directly adjacent to the old post (2–4 inches away)
- Wait 48–72 hours for concrete to cure (per AFA standards)
- Bolt the new post to the old post with carriage bolts (2–3 bolts, evenly spaced)
- Transfer fence panel attachments to the new post if needed
Pros: Strong repair. No fence disassembly.
Cons: Two posts visible side by side. Takes up more space at the fence line.
Cost: DIY: $30–$60 per post. Professional: $150–$300 per post.
Method 3: Concrete Collar Reinforcement
For posts that are rocking in their existing concrete footing but aren't rotted.
When to use: Post pulls away from the concrete but the wood is sound. Common after freeze-thaw cycles in Denver, Chicago, and northern climates.
Process:
- Dig around the existing footing to expose it
- Push the post plumb and brace it
- Pour new concrete around and over the existing footing, creating a larger collar
- Crown the new concrete above grade for drainage (per AFA concrete module standards)
- Wait 48–72 hours for cure
Pros: No new materials except concrete. Post stays in original position.
Cons: Only works if the wood is solid. Doesn't fix rot.
Cost: DIY: $10–$20 per post. Professional: $100–$200 per post.
Method 4: Full Post Replacement (In Place)
Remove the old post and set a new one in the exact same location, transferring the fence panels from old to new.
When to use: Post is completely rotted, broken, or damaged beyond repair. This is the most thorough fix.
Process:
- Support the fence. Brace the panels on both sides of the damaged post with temporary stakes or a helper holding them level.
- Detach panels. Remove screws/nails connecting the rails and pickets to the damaged post.
- Remove the old post. Cut at ground level, then extract the concrete footing:
- Option A: Dig around the footing and pry it out (labor-intensive but effective)
- Option B: Leave the old concrete in the hole — it provides drainage. Drill a new post hole adjacent to (or partially overlapping) the old footing.
- Set the new post. Per AFA standards: dig to proper depth (one-third of total post length minimum), set in concrete, plumb in two directions, brace. See our post setting methods guide for options.
- Wait for cure. 48–72 hours minimum before attaching panels.
- Reattach panels. Connect rails and pickets to the new post.
Pro tip: If replacing a wood post, consider upgrading to a steel post with a wood-post bracket. This eliminates the ground-contact rot problem permanently. The AFA's wood discipline covers metal post installation as a standard method for wood fences.
Cost: DIY: $50–$100 per post. Professional: $200–$500 per post (includes extraction, new post, concrete, reattachment).
Preventing Future Post Rot
After repairing, invest in prevention for the remaining posts:
- Metal post bases: Retrofit brackets that lift the wood post above ground contact
- Concrete crowning: Ensure all footings slope away from the post — no water pooling
- Gravel drainage: Add gravel around the base of posts in wet soil
- Post wrap: Copper naphthenate or similar wood preservative on the below-grade portion
- Steel posts for next replacement: When the next post fails, replace with galvanized steel
Our wood fence maintenance guide covers the full prevention program, and our fence replacement cost guide helps you decide between ongoing repairs and full replacement.
Frequently Asked Questions
How many rotted posts justify a full fence replacement?
As a rule of thumb: if more than 30% of your posts are failing, full replacement is more cost-effective than individual repairs. At that point, you're chasing failures — fix one, and the next one goes within months.
Can I replace a post myself?
Methods 1–3 (mender, sistering, concrete collar) are solidly DIY. Full replacement (Method 4) requires extracting the old footing and is physically demanding. A helper is essential. If you're unsure, the DIY vs. pro comparison can help you decide.
How long does a post repair last?
Steel mender: 10–15 years. Sistered post: 15–20 years (as long as the new post). Concrete collar: 5–10 years if the underlying issue was movement, indefinite if it was just loose bonding. Full replacement with metal post: 30+ years.
Find a Fence Contractor Near You
- Houston fence companies
- Jacksonville fence companies
- Tampa fence companies
- Atlanta fence companies
- Dallas fence companies
- Browse all fence companies →
Are you a fence contractor? Apply for FA Verified status →
*Post setting and concrete standards per American Fence Association Fence Installation School Core Training modules 7, 8, and 9.*