12″ (305mm) wax cone / conical bolt box. The most common size for standard agricultural portal frame foundations. Protects bolt threads and creates levelling access.
What Is a Wax Cone?
A wax cone (also called a conical bolt box or void former) is a waxed cardboard cone used when setting holding down bolts into concrete foundations. It creates a conical void around the bolt, giving you the lateral adjustment needed to line up your steelwork accurately when the columns are erected.
Without a wax cone, the concrete would set tight around the bolt with no room for movement. That makes it almost impossible to get your base plates and columns to line up — even a few millimetres out and the bolt holes won’t match. The cone gives you the tolerance to nudge each bolt into the exact position before grouting.
Which Size Do I Need?
The wax cone depth should match your foundation depth and bolt projection. As a general guide:
- 9″ (229mm) — shallow pad foundations, lighter structures
- 12″ (305mm) — standard pad foundations for agricultural portal frames — most common size
- 15″ (380mm) — deeper foundations or where more bolt adjustment is needed
- 18″ (457mm) — deep foundations, industrial buildings
- 21″ (564mm) — very deep foundations, heavy-duty structures
- 24″ (610mm) — the deepest foundations, large industrial or commercial buildings
Your engineer’s foundation drawing will show the pad depth and bolt projection — choose a cone that covers the full threaded length above the bend in the bolt.
How Many Do I Need?
One wax cone per holding down bolt. A typical base plate has 4 holding down bolts, so you need 4 wax cones per base. For a 6-bay building with 7 frames, that’s 28 wax cones minimum, plus extras for gable post bases.
What Else Do I Need?
Each base connection needs: holding down bolt sets, square plate washers, wax cones, and the base plate itself. We sell all of these — check our full holding down bolt range.
Why Buy From Us?
- Sold individually — order exactly what you need, no box quantities
- Full size range — 9″ to 24″ to suit any foundation depth
- Next-day dispatch — order before 12pm for same-day dispatch
Delivery Information
Next-Day Dispatch
Orders placed before 12pm (Mon–Fri) are dispatched the same day for next working day delivery (subject to courier availability).
Standard Delivery Cost
Shipping is calculated at checkout based on weight. Depending on weight or order we will send components in boxes or pallet delivery.
Packaging
All components are securely pallet-wrapped and labelled, ensuring safe and tidy arrival on-site.
Order Tracking
You’ll receive an email with tracking info once your order leaves our workshop.
Returns
We supply components made to spec, if you’ve ordered the wrong item or something’s arrived damaged, just let us know within 5 working days and we’ll sort it.
For full details, see our Returns Policy.
