What is a Through Bolt?


A through bolt is a torque-controlled steel anchor designed for fixing into non-cracked concrete. It consists of a threaded bolt, washer and nut, and is a fast and secure way to anchor heavy loads. They are called through bolts as they pass through the structure being fixed straight into the concrete.


Also known as


Concrete fixings, rag bolts or ‘knock-in’ anchors.


Why use Through Bolts?


Through bolts are used in construction projects that require strong anchoring. Use them to bolt down heavy machinery in warehouses, pallet racking or structural elements on building sites. They are ideal for railings, crash barriers and other safety-critical applications, ensuring protection for people in the workplace or at leisure.


Through Bolts: How they work


Drill a hole of the same diameter as the bolt using an SDS hammer drill. Insert the bolt into the hole, and as you tighten the nut, the cone bolt pulls into the expansion clip, forcing it against the hole wall. This twisting (or torque) effect creates a secure anchor.


Tip: You should carefully install through bolts, always using the correct drill size to match your application.


Features and specifications



  • Diameters range from M6 to M24.

  • Lengths available from 60mm to 220mm.

  • Available in zinc-plated finishes or durable stainless steel.


Buy your Through Bolts at Fastco


We stock a huge range of through bolts from leading brands JCP and Fischer, with free delivery on orders over £30.* Order now through our website, email us at sales@fastco.co.uk, or call us on 01270 252326.




*Restrictions apply; please see our delivery page for details.