Arguably one of the most essential components of any construction project, the importance of selecting the correct screw for the job can’t be underestimated. Although all screws have some commonalities – a length of metal with an external thread and a head that’s designed to hold two pieces of material together, there are dozens of different screw designs, each of which has been created for a specific purpose. Some types of screws include self-drilling metal screws, woodworking screws, lag screws, chipboard screws and many more.
Screws may be made from stainless steel, zinc, aluminium, brass, titanium or copper, as well as other metals when a specialist project requires them. They may be coated to prevent corrosion or to make insertion easier. Customers can choose from self-tapping screws (screws that are designed to cut a thread into the material in which it’s being driven) or screws that need to be inserted into a pre-drilled hole.
Screws also come in a wide range of widths, head sizes and types, lengths and shapes, which means there’s a screw out there that’s suitable for almost any fastening application.
When selecting screws, it’s important to choose the type that’s right for the job under consideration – using the correct screw makes a big difference to the stability and longevity of the finished project.
You can spot a chipboard screw by the length of its thread. Traditional woodworking screws have a thread that typically extends between half and two-thirds of the way up the screw’s shaft, leaving unthreaded metal at the top end of the screw, beneath the head. In comparison, a chipboard screw is threaded with one continuous thread down the entire length of the screw. The design of a chipboard screw means that it provides a particularly strong, durable fastening, making it ideal for large projects such as decking.
Also known as lag screws, coach screws are heavy-duty screws that are mainly used for fastening heavy timber to masonry, or timber to timber. Occasionally they may be used to join concrete to masonry. Coach screws are threaded along their full length and have a hexagonal head that doesn’t have a thread on it. Coach screws aren’t self-tapping – you will need to drill a pilot hole (or, for a load-bearing fastening, drill a complete hole and insert a plug for the screw to sit in) to ensure the coach screw ends up in the correct position.
As the name suggests, these are generic, all-purpose screws that can be used for a wide range of applications. Usually, these are flat head (countersunk) screws that rest flush with the surface they’re being inserted into. Threads may extend fully or partially up the shaft. All-purpose screws can be used to fasten metal, wood, plastic or chipboard. The head may vary, with Torx, Philips and slotted options available. Multi-use screws are also on offer in a variety of lengths and widths, ensuring there’s usually an option that’s right for your chosen project.
Plasterboard screws differ from other types of screws because they are specifically designed to securely fasten plasterboard (or drywall) into position. They are characterised by deeper threads than you will find in other screws. The deeper threads enable the screw to sit more securely in the drywall. Depending on the surface to which the drywall is to be fastened, it’s possible to buy fine thread drywall screws (for screwing drywall to metal), coarse thread drywall screws (for fastening drywall to timber) or self drill drywall screws (these are frequently used when drywall is used to create interior walls or ceilings).