What Are Holding Down Bolts?
Holding down bolts (also called foundation bolts) secure steel columns to concrete foundations. They’re cast into the concrete pad before the steelwork arrives on site, with the threaded end projecting above the slab to receive the base plate, washer, and nut.
Our bolt sets are manufactured to BS 7419 in Grade 8.8 high tensile steel, supplied complete with nut and ready to use with wax cone bolt boxes (available separately).
Choosing the Right Size
The bolt size you need depends on your column section and the loads specified by your structural engineer. As a general guide for standard portal frame buildings:
| Column Section | Typical Bolt Size | Common Lengths |
|---|---|---|
| 152–178 UB | M16 | 300mm, 375mm |
| 203–254 UB | M20 | 375mm, 450mm |
| 305+ UB or high-load applications | M24 | 450mm, 600mm, 750mm |
Always confirm sizes against your engineer’s foundation drawing. If you’re unsure, send us your GA drawing via WhatsApp and we’ll help you pick the right set.
How Many Do I Need?
Most portal frame base plates use 4 holding down bolts per base. A typical single-span portal frame has 2 bases (one each side), so you’ll need 8 bolts per frame. For a 6-bay agricultural shed, that’s roughly 56 bolts total (7 frames × 8 bolts), plus spares.
Don’t forget to order your wax cone bolt boxes at the same time, one cone per bolt.
Installation Tips
- Set bolts into position using a bolt box (wax cone) before the concrete pour
- Ensure the threaded section projects at least 50mm above the finished slab level
- Check bolt positions against your base plate hole centres before concrete sets
- Allow concrete to reach adequate strength before tightening
- Use a bolt cracker if adjustment is needed after the concrete pour
Why Buy From Us?
Unlike larger suppliers who sell in boxes of 16 or require minimum orders, we sell holding down bolts individually — buy exactly the quantity you need.
- Buy from 1 bolt – no minimum order on individual sizes
- BS 7419 compliant, Grade 8.8 high tensile steel
- Complete sets with nut included
- Quick quotes via WhatsApp for larger orders
Delivery Information
Estimated Dispatch: 4–7 Working Days
These items are supplied to order. Please allow 4–7 working days for dispatch from order confirmation. This ensures we maintain consistent quality and availability while keeping pricing competitive.
Standard Delivery Cost
Shipping is calculated at checkout based on weight and order size. Depending on the quantity ordered, items may be shipped in boxes or via pallet delivery.
Packaging
All components are securely packaged and clearly labelled to ensure safe and tidy arrival on site.
Order Tracking
You’ll receive an email with tracking information once your order has been dispatched.
Returns
We supply components to specification. If you’ve ordered the wrong item or something arrives damaged, please let us know within 5 working days and we’ll get it sorted.
For full details, see our Returns Policy.
