Concrete is the professional standard for setting fence posts — but it's not always the best choice. Depending on your soil, climate, fence type, and budget, gravel, expanding foam, or drive-in posts might actually perform better or last longer.
The AFA's Fence Installation School teaches concrete as the default, noting that "concrete is not used to make fences stronger, but to provide compressive strength around posts" and that "pouring concrete into a post hole is faster than compacting backfill around the post." But the training also acknowledges that different soil types and conditions may call for different approaches.
Method 1: Concrete (The Standard)
How It Works
Mix concrete (or use pre-mixed bags), pour around the post in the hole, let it cure for 48–72 hours before loading.
Specifications
Per the AFA concrete mixing module:
- Cement comprises 10–15% of the mix by volume
- Portland cement is the standard type (not a brand name — a generic term for the cement used in virtually all concrete)
- Through hydration, concrete hardens and continues getting stronger for years
- "28-day strength" is the standard benchmark — concrete reaches about 70% of this within 7 days
Strengths
- Maximum lateral strength. The concrete cylinder resists wind load, impact, and the pulling force of stretched fence fabric better than any other method.
- Professional standard. Every fence contractor uses it. Every ASTM standard assumes it.
- Predictable. Proven over decades in every soil type and climate.
Weaknesses
- Traps moisture at wood post base. Concrete holds water against the wood, accelerating rot at the ground-level contact point. This is the #1 cause of wood fence post failure.
- Permanent. Removing a concrete footing requires significant effort — digging, breaking, hauling.
- Cure time. You can't load the fence for 2–3 days minimum after pouring.
- Frost heave. In cold climates like Minneapolis and Denver, concrete footings above the frost line can heave upward during freeze-thaw cycles, pushing posts out of alignment.
Best For
All fence types, especially chain link (where fabric tension pulls on posts), ornamental metal, and any fence requiring maximum rigidity. Standard in Dallas and most warm-climate markets.
Cost: $3–$6 per post (pre-mixed bags)
For detailed concrete specifications, see our concrete footings guide.
Method 2: Gravel/Crushed Stone
How It Works
Fill the post hole with ¾" crushed angular stone, compacting every 4–6 inches with a tamping bar. The angular faces of the crushed stone lock together and grip the post.
Strengths
- Superior drainage. Water flows through gravel rather than pooling against the post. This dramatically extends wood post life in wet climates.
- Frost heave resistance. Gravel below the frost line doesn't heave because water drains through rather than freezing in place. Excellent for Minneapolis, Denver, and northern climates.
- Removable. Posts set in gravel can be pulled or adjusted without breaking concrete.
- Immediate loading. No cure time — you can hang fence the same day (though waiting 24 hours for settling is wise).
Weaknesses
- Lower lateral strength. Gravel doesn't resist horizontal force as well as concrete. Not suitable for chain link (fabric tension pulls posts inward) or tall fences in high-wind areas.
- Requires proper compaction. Loose gravel settles and posts lean. Each 4–6-inch layer must be tamped firmly.
- Larger hole recommended. 14–16-inch diameter vs. 10–12 for concrete.
Best For
Wood privacy fences in wet climates, areas with frost heave, temporary or relocatable fences, and situations where future post replacement is likely.
Cost: $2–$4 per post (crushed stone)
Method 3: Expanding Foam
How It Works
Two-part polyurethane foam is mixed and poured into the post hole. It expands to fill the cavity and hardens within 15–20 minutes.
Strengths
- Fast. Sets in minutes vs. days for concrete.
- Lightweight. A foam kit weighs 3–5 lbs vs. 50+ lbs for concrete bags.
- Good drainage. Foam doesn't absorb or hold water against the post.
- Reasonable strength. Manufacturers claim strength comparable to concrete for residential fence posts.
Weaknesses
- Cost. $8–$15 per post — 2–4× the cost of concrete.
- Not proven long-term. Concrete has 100+ years of track record. Foam has been mainstream for about 10 years.
- UV degradation. Foam exposed above grade degrades in sunlight. Must be buried.
- Not suitable for heavy loads. Not recommended for gate posts, tall commercial fences, or chain link with tension fabric.
Best For
Light to medium-duty wood and vinyl fences, DIY installations (lightweight, fast, no mixing), and remote locations where hauling concrete bags is impractical.
Cost: $8–$15 per post (foam kit)
Method 4: Drive-In (No Digging)
How It Works
Metal posts with pointed bases are driven directly into the ground using a post driver (manual sleeve or hydraulic). No hole digging, no concrete.
Strengths
- Fastest method. A hydraulic driver sets a post in under a minute.
- No concrete waste. Nothing to mix, pour, or cure.
- Easy removal. Posts pull straight out.
Weaknesses
- Metal posts only. You can't drive a wood or vinyl post.
- Soil-dependent. Only works in soft to moderately firm soil. Rocky soil, caliche (Phoenix), and hardpan stop the post short. Per the AFA's post hole digging module, underground obstructions can prevent proper installation.
- Less stable. No concrete or gravel anchor means less resistance to wind load and lateral force.
- Limited to light duty. Suitable for chain link up to 6 feet and light ornamental. Not for heavy privacy fences.
Best For
Chain link fences in soft soil, temporary installations, and agricultural/rural fencing.
Cost: $0 per post (no fill material) + post driver rental ($40–$80/day)
Comparison Chart
| Factor | Concrete | Gravel | Foam | Drive-In |
|---|---|---|---|---|
| Lateral strength | ★★★★★ | ★★★ | ★★★★ | ★★ |
| Drainage | ★★ | ★★★★★ | ★★★★ | N/A |
| Frost heave resistance | ★★ | ★★★★★ | ★★★★ | ★★★ |
| Speed | ★★ | ★★★ | ★★★★★ | ★★★★★ |
| Cost per post | $3–$6 | $2–$4 | $8–$15 | $0 |
| Removability | ★ | ★★★★ | ★★★ | ★★★★★ |
| Long-term track record | ★★★★★ | ★★★★ | ★★ | ★★★ |
Frequently Asked Questions
Is concrete or gravel better for fence posts?
It depends on your priority. Concrete gives maximum strength for chain link and tall fences. Gravel gives better drainage and frost heave resistance — extending wood post life in wet and cold climates. For most wood privacy fences, gravel is an excellent choice. See our post depth guide for depth requirements regardless of method.
Does expanding foam really work?
For light to medium-duty residential fences, yes. Independent tests show comparable hold strength to concrete for standard wood posts. We don't recommend it for gate posts, commercial fences, or chain link under tension.
Can I use gravel for a chain link fence?
Not recommended. The tension from stretching chain link fabric pulls terminal posts inward, and gravel doesn't provide enough resistance. Use concrete for all chain link fence posts — it's the AFA standard per ASTM F567-07. See our chain link guide.
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*Post setting and concrete specifications per American Fence Association Fence Installation School Core Training modules 8 and 9.*