Concrete Bolts

Commonly known as thunder bolts, our concrete bolts are useful for a variety of materials. They can be fixed directly into concrete, brick and blockwork, stone and timber without the need for a plug.

There is no expansion with masonry bolts, making them a stress-free fixing. This means that with no expansion forces, these bolts can be used closer to the edge of the substrate than traditional fixings without the fear of damaging it.

Bolts for concrete have a self-tapping thread that effectively creates a nut to the bolt within the substrate itself, holding it firm. Self-tapping is a tried and tested process with wood and metals that can also now be applied to other materials such as brick and stone.

We offer a wide range of stainless steel concrete bolt size options, all featuring a zinc-plated finish. It is important to note that concrete bolts are not to be confused with concrete screws. The latter is another type of heavy-duty fixing that feature a countersunk head and a sharp point.

Using Concrete Bolts

The drill size required for a concrete bolt is 2mm less than the diameter of the bolt. With our thunder bolts, the drill size and the length of the bolt (from the underside of the head) are stamped upon the bolt head. This does differ by manufacturer, so you should always check the drill size required – some manufacturers will stamp the bolt diameter rather than the drill size required. Both of these dimensions are always stated in our product descriptions.

Also please bear in mind that the hole that you drill in the item being fixed should be the same diameter as the concrete bolt – so if you are using a 12mm diameter bolt, you will still need a 12mm drill to penetrate the item that is being fastened before using the 10mm drill for the substrate.

For more information on how to use concrete bolts, check out our guide on how to bolt into concrete!