Setting Fence Posts in Concrete: How Your Fence Stays Straight
Dig point foundations, align posts and set them in concrete – permanently stable and in line
Disclaimer
This guide has been prepared with great care. Nevertheless, we accept no warranty for the accuracy, completeness or currency of its contents. You follow this guide at your own risk – any liability for personal injury, property damage or financial loss arising in connection with its use is excluded. The contents do not replace professional advice for your individual situation. Always observe the manufacturer instructions of your tools and materials as well as applicable local regulations (e.g. building codes, neighbour law, utility line enquiries before digging). Work on electrical, gas or water lines and on load-bearing structures must only be carried out by qualified professionals.
Dig point foundations, align posts and set them in concrete – permanently stable and in line
Whether double-wire mesh, wooden or privacy fence – the posts carry the entire construction and decide whether the fence still stands straight after years. The craft challenge lies in three things: the correct foundation depth (frost-free!), the exact alignment, and getting posts plumb before the concrete sets. With a string line, spirit level and patience, this is very doable. Important beforehand: clarify the boundary line and neighbour-law rules – and check for buried utility lines before digging.
Tools
- Post-hole digger or spade
- Long spirit level and plumb line
- Mason’s string and wooden stakes
- Mixing tub and trowel
- Folding rule
- Wheelbarrow if needed
Materials
- Fence posts (galvanised/powder-coated, or wood with post anchors)
- Dry-mix / rapid-set concrete (approx. 1–2 bags of 25 kg per post)
- Gravel or crushed stone for the base layer
- Water
Step by Step
Stake out the line and tension the string
Stake out the start and end points of the fence and stretch a mason’s string tightly between them – it is your reference for the entire build. Mark the post positions in the grid of the fence panels (typical for double-wire mesh: 2.50 m plus post width). Measure twice – corrections are expensive later.
Dig the foundation holes
For each post, dig a hole of approx. 30×30 cm (40×40 cm for privacy fences with higher wind load) and 80 cm deep – so the foundation sits below the frost line. A post-hole digger makes narrower, cleaner holes than a spade. Place 5–10 cm of gravel at the bottom as a drainage layer.
Mix the concrete
Mix dry-mix concrete with water to an earth-moist to plastic consistency as instructed. Earth-moist concrete has the advantage that the post stands without bracing during installation. Rapid-set concrete is load-bearing after 1–2 hours but costs a little more.
Set and align the posts
Place the post in the hole, fill in the concrete in layers and compact it (poke with a wooden batten). Align the post continuously: height to the string, line to the string, plumb with the spirit level on two faces offset by 90°. In windy weather or with softer concrete, brace with battens.
Shape the concrete surface
Finish the concrete just below ground level and slope it slightly away from the post so rainwater runs off and does not pool at the post – especially important for wooden posts in anchors. In lawn areas, the foundation can end 5 cm below the turf so grass grows over it later.
Let it cure, then mount the panels
Normal dry-mix concrete takes 24–48 hours before it carries assembly loads; concrete reaches full strength after 28 days. Mount mesh or fence panels only when the posts are firm – any movement in fresh concrete permanently weakens the foundation.
Safety First
- Before digging, obtain utility line information or check where power, water and telecom lines run – ask the utility company if in doubt.
- Cement-based concrete is highly alkaline: wear gloves and safety glasses, avoid skin contact.
- Clarify boundary distances and any local fencing bylaws in advance – this avoids disputes with neighbours and tearing the fence down again.
- Lift heavy bags with a straight back or work in pairs.
Mistakes You Should Avoid
Foundations too shallow
Foundations above the frost line (60–80 cm depending on the region in Germany) are lifted by frost – the fence leans after two winters. 80 cm depth is the safe standard.
Setting posts “by eye” without a string
Just 2 cm of offset per post adds up to a visibly wavy fence, and prefabricated panels no longer fit between the posts. The mason’s string is not optional.
Concreting wooden posts in directly
Wood set in concrete rots at the transition zone within a few years. Wooden posts belong in H-anchors or bolt-down post supports set in the concrete – the wood itself stays above ground.
Common Questions
How deep must a fence post be set in concrete?
The foundation should sit below the frost line, i.e. 60–80 cm deep depending on the region. As a rule of thumb, about a third of the post length belongs in the ground or foundation, more for tall privacy fences.
How much concrete do I need per fence post?
A standard foundation of 30×30×80 cm requires around 70 litres of concrete, roughly 3–4 bags of 25 kg dry mix, minus the volume of post and gravel layer. In practice, 2–3 bags are usually sufficient depending on hole size.
How far apart may fence posts be?
The fence system dictates this: double-wire mesh has a 2.50 m grid, wooden fence panels usually 1.80–2.00 m. For self-built fences, 2.00–2.50 m is a good compromise between stability and material use.
Do I need a building permit for a fence?
Enclosures up to a certain height (often 1.20–1.80 m, depending on the federal state and municipality) are usually permit-free, but neighbour law and local bylaws apply. Check with your municipality before building – especially for fences along roads and property boundaries.
Rapid-set or normal concrete?
Rapid-set concrete cures in 1–2 hours and lets you keep working quickly – practical if you want to set many posts in one day. Normal dry-mix concrete is cheaper and leaves more time for aligning. For beginners, the longer working time is often the bigger advantage.
When is a professional worth it?
With long fence runs, sloping ground, rocky soil or when gates come into play, the weekend project quickly becomes a science: gates need considerably larger foundations, fences on slopes need clean height stepping. We build fences of all kinds – from double-wire mesh to privacy screens to natural fences – including earthworks, foundations and gates. With a mini excavator and earth auger, even 50 metres of fence are set in no time, straight and frost-proof.
