Bolts & Threaded Screws

Bolts and other threaded mechanical fixings are often utilised within the construction industry in many structural applications. The most common types of these fixings are threaded nuts and bolts that are used to hold structural components together. For the most part they are made from steel and are threaded in order to receive a nut, or to be threaded into another component. Within construction they are typically very thick in comparison to the thickness of other fasteners such as nails or screws, making them an excellent choice in tensile scenarios. Here we shall take a look at the different types of bolts and threads and their applications, as well as their limitations.  

Machine screws

Machine screws are a type of small screw that is threaded to receive into a threaded hole or nut. The head has some sort of drive type that can be driven with a screwdriver or drill. Machine screws typically see use in engineering and machinery production, though they see some use in residential construction. The most common uses for machine screws in construction are as part of hardware or ironmongery that we install. One example that comes to mind are the hex drive machine screws that are used to tighten a door handle onto the square through rod.

Coach bolts

Coach bolts see much use in the building industry due to their rigid construction and versatility. They are perfect for use in structural applications, such as bolting together beams or fixing down steels. Bolts as a broad category come in many varieties, though there are a few specific types that see common use in residential construction. Mushroom head bolts are used to bolt together timbers, with their wide head distributing a large load over the surface of the material. These bolts are typically specified to be M12 in diameter of their shank, and are 130mm or 190mm long, for bolting doubles and triples respectively. Other sizes are available from suppliers. These bolts are made for steel and are coated to resist corrosion.   

Chemical adhesive bolts/threaded rods

Threaded rods are a type of bolt that are intended to be used in conjunction with chemical resin adhesive. The bolts themselves come in a variety of sizes and are made from steel that is coated for resistance to corrosion. The bolts are driven into a hole of the correct size that has been filled with resin and the adhesive is allowed to set. The threaded rods then protrude out of the masonry and are fixed in place. Once the adhesive is dry, materials such as timber can be placed over the threaded rods and fastened to the masonry using the nuts and washers provided. This is a very effective method of securing structural members to masonry.  

Nuts

Nuts are hexagonal pieces of steel with a threaded hole through the middle of them. The thread pitch and hole diameter are sold in relation to the thread pitch and shank diameter of available bolts. The purpose of a nut is to receive onto the end of a bolt and be tightened against the material/s in between the nut and the head. This draws the materials together and provides a secure form of fastening. Nuts are often sold with bolts in packs.