Galvanised Thunderbolts – Multi Purpose Fixing Bolt – Hex Head / Hex Flange Head

Galvanised hex thunderbolts have been a staple on UK building sites for decades, and there is a good reason they have not been replaced. The Thunderbolt is the original self-tapping anchor bolt, designed to fix directly into masonry without a separate anchor insert. The galvanised finish adds a solid layer of corrosion resistance, making these suitable for internal and external use where moisture is a factor.

The principle is simple and effective. You drill a standard-sized hole, drive the bolt in, and the thread cuts directly into the substrate. The material itself acts as the nut. No sleeve, no plug, no faff. For anyone who has spent time on site fumbling with plastic wall plugs on a cold morning, this will feel like a revelation.

Where Galvanised Hex Thunderbolts Get Used

These are general purpose anchor bolts that suit a wide range of construction trades. The hex head and hex flange head options give you a clean, wrench-driven fixing that sits flush or just proud of the surface depending on your application. Both heads work with a standard socket or spanner, which keeps tool requirements down on site.

One of the practical advantages of the Thunderbolt design is the ability to fix closer to edges and closer together than traditional expanding anchors. Fewer restrictions on positioning means less time re-marking and re-drilling. The varying embedment depths also give you some flexibility depending on load requirements and substrate depth.

Temporary and Permanent Fixing

A detail worth noting: galvanised hex thunderbolts are fully removable. This makes them genuinely useful on temporary structures, formwork, hoarding, or anywhere a fixing needs to come back out cleanly. Most anchor systems damage the substrate on removal. These do not, which keeps your options open.

Available across a broad range of sizes from 6mm up to 16mm diameter and lengths up to 200mm, there is a variant here for light-duty bracket fixing right up to structural steelwork connections. Drill size matches the bolt diameter, so there is no guesswork involved in bit selection.