A Thunderbolt is a self-tapping masonry anchor — you'll also see them sold as concrete bolts or masonry screws. Unlike a sleeve anchor or a through bolt, a Thunderbolt doesn't expand. Its hardened thread cuts into the base material itself, so there's no wall plug, no resin and no outward pressure on the concrete, brick or block.
That single difference drives everything that makes Thunderbolts popular: you can install one in seconds with an impact driver, fix close to edges and closer together than expansion anchors allow, and unscrew the fixing cleanly when the job is temporary or needs repositioning.
One terminology trap to clear up first: "thunderbolt" started as a brand name (Ramset/Reid's Thunderbolt™) but has become a generic trade term in the UK. When someone asks for "a thunderbolt", they almost always mean any self-tapping masonry anchor of this type.
How to install a Thunderbolt
- Drill a hole the same diameter as the anchor, slightly deeper than you need — the extra depth
