Skill: Dig Holes to Correct Size and Depth – Keep Drive Clear and Tidy
Skill level: 1
Gate Mechanics
Learning Objective
Understand how to dig clean, accurate post holes for gate installations, ensuring structural reliability while maintaining a safe and tidy worksite.
1. Why Proper Hole Digging Matters
A poorly dug or insufficiently large hole can lead to:
Posts moving over time (especially under motor stress)
Concrete cracking or failing
Uneven or twisted gate alignment
Damage to cables or utilities
An untidy site that annoys customers or causes accidents
✅ A well-prepared hole saves time, improves quality, and keeps everyone safe.
2. Tools & Materials You’ll Need
Spade
Post hole digger
Breaker and bits
Rubble sacks
Tarp
Hand trowel for shaping
Bucket/barrow for spoil
Dust sheet or tarp
Tape measure or digging stick
PPE (boots, gloves, eye protection)
Marker paint or chalk
Barrier tape or cones
3. Know Your Required Hole Dimensions
Gate Type → Typical Hole Size (W x L x D)
Standard swing gate 200mm oak post → 400mm x 400mm x 700–1000mm deep
Heavy motorised post → 500mm x 500mm x 1000mm+ (or pad base)
Cantilever bases → 500mm w x 700mm deep x 1500-2500mm+ with chem fix
Guide posts → 400mm x 400mm x 600mm (varies)
Brick piers → 650mm x 650mm x 900mm (varies)
As a rule, the softer the ground the bigger the hole required to ensure stability
Always refer to the job sheet or structural drawing if provided.
4. Step-by-Step: Digging the Hole
🔹 A. Plan Before You Dig
Mark out hole size with spray paint or chalk, extend the marks beyone the corners so they can be see after digging has started.
Think about where spoil will go – don’t block the driveway or create trip hazzards
Lay dust sheets or tarps to protect surfaces like tarmac, lawn, pavers, gravel.
Check for underground services (power, water, ducting) refer to maps, local knowledge, obvious signs like inspection covers.
If unsure, dig carefully by hand or probe first (CAT), use an insulated spade.
🔹 B. Dig with Accuracy and Care
Dig square-sided holes, not cone-shaped
Use post hole diggers or breaker bar to go deeper neatly
Shape the bottom flat – no pointy holes!
Dig slightly deeper than required and backfill if needed for precision
🔹 C. Stay Tidy and Safe
Place spoil on tarps or in buckets, not directly on tarmac or block paving
Keep the area clear of trip hazards
Ideally fill holes/fit posts the same day, especially if they are a danger to the public or if it looks like rain.
If leaving holes open, mark and barricade with cones or tape, or fill with rubble sacks full of spoil for easy removal later.
Tidy up as you go — don’t wait until the end of the day, spoil gets harder to move the longer it's left.
5. Pro Tips
For deep holes, use a measuring stick marked with hole depth
Wet or sandy ground? Consider shuttering or post mix that sets fast
Clay ground? Dig wider at the bottom to resist frost heave
Double check gate swing direction and clearance before setting post base level
⚠️ 6. Common Mistakes to Avoid
🚫 Digging too shallow — leads to post wobble
🚫 Throwing spoil all over the customer’s drive
🚫 Leaving edges messy or uneven — affects post plumb
🚫 Hitting ducting/cables because you didn’t check
🚫 Not checking post height before backfilling
🚫 Leaving holes unmarked — safety hazard!
7. Safety References
Refer to SSOW-05: Excavation and Digging Safety and SSOW-01: General Site Safety for full safe systems of work when carrying out digging tasks.
