Parabolt screw, what is it and how to use?


What do you use to attach structures to the wall or ceiling? Parabolt can be the solution to your problem when you need to fix something to the concrete. As well? You do not know what it is? In this article, the World of Electrical shows how to use the Parabolt mechanical anchor bolt.

Fixing structures in civil construction is more common than you might think, but in some situations using only nails or srews with a screw anchor is not recommended, as they do not support the weight of the material to be fixed. Thus, the need arises to use mechanical anchor bolts to fix heavier structures such as, for example, cable trays, ceiling fans, chandeliers, air conditioning condensers, etc.


The parabolt screw is a very versatile expansive fixing system capable of supporting structures on surfaces, being able to withstand high loads and widely used in several types of works providing a safe and fast assembly.

Each parabolt consists of a bolt or tie, a washer, a nut, a jacket also called a cap, capsule or shirt and a wedge. On the market, we can find the parabolt in various sizes, which can be classified in inches or millimeters. It is very important to know the ideal size for each situation, where it will be fixed. Because there are several types of anchor bolts for each situation.

The best-known model of parabolt screw is the CBA with stud, which is the most suitable for direct use in concrete. Another well-known anchor model is nylon, which is used to anchor parts in hollow structures such as brick or concrete block for example. The nylon parabolt anchor consists of a screw, a washer, a nylon cover, and a wedge. An interesting detail is that the wedge is already attached to the nylon cover of the anchor bolt.

CBA parabolt screw with stud and nylon parabolt.

How to assemble and fix the Parabolt

The assembly of the parabolt is very simple, first you put the nut on the screw, then the washer, then just place the capsule with the side cuts facing downwards and finally the wedge with the conical part facing upwards against the capsule.

Assembly of CBA anchor bolt with a prisoner.

Now to fix the mechanical anchor bolt on the wall, first, the hole where the parabolt will be inserted must be drilled, always remembering to check if the dimensions of the anchor bolt and drill bit are the same. After the drilling is done, just place the anchor bolt in the hole if necessary, use a hammer to assist in the insertion, and then tighten the nut using a wrench of the same diameter.

Fixation of CBA parabolt with the prisoner on the wall.

Parabolt operation

The moment the nut is turned, the wedge is screwed and rises towards the capsule. The more it tightens, the higher the wedge rises and the more the capsule expands.

The mechanical operation of an anchor bolt.

In the nylon model as the screw is tightened, the nylon cover deforms and fixes to the piece, even if it is a hollow hole or has a thin wall.

Parabolt operation

The great advantage of replacing screw bushings with mechanical anchors is the safety and speed they offer. A common example is when installing a ceiling fan, as the fan makes constant movement during operation, over time it can damage the conventional bushing.

In addition to using a good mechanical anchor bolt, another key point to ensure a good fixation is knowing how to make the hole in the structures correctly. In this video from the World of Electrical, we show how to choose between the types of drills.

If you have any questions or curiosity about the subject, leave it in the comments and we will answer it! The website and channel of Mundo da Elétrica are full of content on the subject, so feel free to access articles and videos related to the subject.