The post is the most critical structural component of a timber fence. Get it wrong and the whole fence leans, rots or fails — often within a decade. Get it right and your fence will stand straight for 30 years or more.

At FPM Building Supplies we stock three types of timber fence posts: treated pine, hardwood and cypress. Here's how they compare.

The Short Answer

If you want the cheapest option that still does the job: treated pine H4. If you want the best balance of performance and value: cypress. If you want maximum longevity and strength: hardwood.

Treated Pine Posts

Treated pine is softwood (typically radiata pine) that has been pressure-impregnated with preservative chemicals to resist rot, termites and fungal decay. The treatment rating is critical:

• H3 — above-ground use only (not suitable for in-ground fence posts)
• H4 — in-ground use in non-critical applications (standard fence posts)
• H5 — in-ground use in severe conditions (wet soils, high termite risk)

Always use H4 or H5 for fence posts. H3 treated pine in the ground will rot within a few years.

Typical Sizes

• 100×100mm in 2.4m, 2.7m and 3.0m lengths
• 125×125mm in 2.4m and 3.0m lengths

Lifespan In-Ground

• H4: 15–25 years in typical Melbourne conditions
• H5: 25–35 years in wet or high-risk conditions

Cost

Most affordable of the three options. Treated pine posts are typically 30–50% cheaper than hardwood.

Pros

• Lowest cost
• Lightweight and easy to handle
• Widely available in standard sizes
• Easy to cut, drill and nail

Cons

• Shorter lifespan than hardwood or cypress
• Can warp or twist if not properly supported
• Treatment chemicals can leach in very wet conditions
• Requires correct treatment rating — H3 is often sold alongside H4 and is easy to confuse

Best For

Budget-conscious residential fencing, temporary fencing, secondary fences (side and rear boundaries where longevity is less critical).

Hardwood Posts

Hardwood fence posts are milled from dense native timbers — typically ironbark, red gum, spotted gum or similar species. These timbers have natural oils and density that make them inherently resistant to rot and termites without chemical treatment.

Typical Sizes

• 100×100mm in 2.4m and 3.0m lengths
• 125×125mm in 2.4m and 3.0m lengths
• 150×150mm in 2.4m and 3.0m lengths

Lifespan In-Ground

• 30–50 years, depending on species and conditions
• Ironbark and red gum are among the most durable species available

Cost

Premium — typically 50–100% more expensive than treated pine.

Pros

• Exceptional longevity
• Natural rot and termite resistance
• Beautiful natural grain and colour
• Very high strength — suitable for gate posts and structural applications
• No chemical treatment required

Cons

• Heavier and harder to work with
• More expensive upfront
• Can check (surface crack) as it dries — cosmetic only, not structural
• Harder to cut and drill — requires sharp, carbide-tipped tools

Best For

Front boundary fences, gate posts, feature fences, high-traffic areas, properties with high termite risk, anywhere longevity is a priority.

Cypress Posts

Cypress pine (Callitris species) is a native Australian softwood with natural oils that give it excellent durability without chemical treatment. It's lighter than hardwood but significantly more durable than treated pine.

FPM stocks two main cypress post sizes:

• 125×75mm — suitable for standard paling fences
• 125×125mm — heavier-duty applications and gate posts
• 175×75mm — for taller fences and structural applications

Lifespan In-Ground

• 25–40 years in typical conditions
• Naturally resistant to termites and rot

Cost

Mid-range — typically 20–40% more expensive than treated pine, but less than hardwood.

Pros

• Excellent natural durability without chemical treatment
• Lighter than hardwood — easier to handle
• Attractive natural appearance with distinctive grain
• Good value for the lifespan offered
• Suitable for use near vegetable gardens (no chemical treatment)

Cons

• Less widely available than treated pine
• Can be harder to source in large quantities
• Not as strong as hardwood for gate posts and heavy structural applications

Best For

Residential paling fences, properties where chemical-free timber is preferred, medium-term fencing where treated pine feels too short-lived but hardwood is over-specified.

Side-by-Side Comparison

	Treated Pine H4	Hardwood	Cypress
Lifespan in-ground	15–25 years	30–50 years	25–40 years
Cost	$	$$$	$$
Weight	Light	Heavy	Medium
Termite resistance	Chemical	Natural	Natural
Ease of working	Easy	Difficult	Moderate
Best for	Budget fencing	Premium/structural	Mid-range fencing

What About Steel Posts?

For Colorbond fencing, galvanised steel posts (100UC H/C posts or SHS square posts) are the standard choice — they're stronger, longer-lasting and better suited to the Colorbond system than timber. Timber posts are typically used for timber paling fences.

Shop Timber Posts at FPM

FPM Building Supplies stocks treated pine, hardwood and cypress posts from our Epping warehouse. Our team can help you choose the right post for your fence height, soil conditions and budget. Visit us at 12 Janine Street, Epping, or call for trade pricing and availability.