50mm Concrete Plinths

50mm Concrete Under-Fence Plinths — Plain, Timberlook & Composite

A 50mm concrete under-fence plinth is the most effective permanent solution for the gap between the bottom of a Colorbond or timber fence and the ground. After many years building and fencing across Australia, I've seen the same problem on thousands of sites: gaps under fences that let in vermin, erode soil, undermine fence posts, and rot timber rails within a few seasons. A concrete plinth eliminates all of it in one installation.

Our 50mm plinths are available in plain grey, timberlook (woodgrain texture), and composite finishes — so you can match the aesthetic of your fence line or garden setting without compromising on structural performance.

Why Install a Concrete Under-Fence Plinth?

• Stops vermin entry — closes the gap that rabbits, rats, and snakes use to access your yard
• Prevents soil erosion — keeps soil from washing under and undermining fence posts over time
• Protects timber fence rails — eliminates ground contact and moisture wicking that causes rot
• Permanent, zero-maintenance fix — concrete doesn't rot, warp, or require painting
• Improves fence appearance — clean, consistent baseline along the full fence line
• Works with existing fences — can be retrofitted under Colorbond, timber paling, and pool fencing

50mm Plinth vs 75mm or 100mm — Which Do You Need?

The 50mm width suits standard residential fence lines where the gap under the fence is less than 100mm and the ground is relatively level. For sites with:

• Uneven or sloped ground — use 75mm or 100mm plinths to bridge larger gaps
• Significant level changes between bays — consider stepped plinth installation with 100mm sections
• Pool fencing compliance requirements — check your state's pool barrier standard for maximum gap-under-fence specs before ordering

Finish Options

• Plain concrete — clean grey finish, suits Colorbond fence lines and rendered boundary walls
• Timberlook (woodgrain) — embossed timber grain texture, suits timber paling fences and natural garden settings
• Composite — blended finish for feature fence lines where aesthetics matter

Installation Notes

50mm plinths are typically bedded into a mortar or concrete haunching at the base of the fence line. For DIY installation:

• Excavate a shallow trench 50–75mm deep along the fence line
• Set the plinth in a 3:1 sand:cement mortar bed, checking level as you go
• Haunch the back face with concrete or mortar for stability
• Allow 24–48 hours cure time before backfilling

On sloped sites, step the plinths at fence post intervals to maintain a consistent reveal above ground.

Pool Fencing & Compliance

If installing under pool fencing, the maximum allowable gap under a pool barrier is 100mm under AS 1926.1-2012. A 50mm plinth reduces the gap but may not eliminate it on uneven ground — measure your actual gap before ordering. For compliance-critical pool fence installs, contact our team and we'll specify the correct plinth height for your site.

Frequently Asked Questions

What is an under-fence concrete plinth?

A concrete under-fence plinth (also called a concrete infill panel or fence base panel) is a precast concrete strip that fills the gap between the bottom of a fence and the ground. It sits at the base of the fence line, bedded into mortar, and provides a permanent, vermin-proof, rot-proof base for Colorbond, timber, and other fence types.

Can I install a 50mm plinth myself?

Yes — 50mm plinths are manageable for a confident DIYer. The main variables are getting the mortar bed level on sloped ground and stepping correctly at post intervals. If your fence line has significant level changes, call us first — we can advise on the right combination of plinth widths for your site.

Will a concrete plinth stop snakes getting under my fence?

A correctly installed plinth with no gaps will significantly reduce snake entry points. The key is continuous installation with no gaps at joins, correct mortar bedding at the base, and haunching at the back. Gaps at fence posts are the most common point of failure — ensure mortar is packed tight around post bases.

How long do concrete under-fence plinths last?

Correctly installed concrete plinths will outlast the fence above them. Concrete is unaffected by moisture, UV, and ground contact. The limiting factor is usually the mortar bed — a properly haunched plinth on stable ground should last 30–50 years without intervention.

Need a delivered price or advice on which plinth suits your fence line? Contact our team — we respond within one business day.