When it comes to screws and fixings, the choice can be overwhelming. Whether you need screws, nails, bits, or nuts and bolts, our buyers guide is here to help.

Screws

 A screw has four main identifying aspects - a head, a shank, a pointed tip, and a thread. The head is the round part your screwdriver connects with to screw it in. The shaft is the ‘body’ of the screw and the thread refers to the raised ridges along the shaft.

Each of these key characteristics comes in many different options depending on what the screw is to be used for in your DIY project. There are different shapes of screw head and different types of screws.

A screw with a hexagonal head is also known as a hex bolt or a hex cap screw and are in fact more similar to bolts, however, do not require the use of a nut.

The most common types of screw head are:

  • Flat head
  • Countersunk
  • Raised
  • Rounded

You will probably have heard of a Phillips head screw and/or the Phillips head screwdriver. These refer to screws with a cross shape in the head, and the Phillips screwdriver has a cross or X shaped blade to correspond. These screws allow the screwdriver to be self-centring. This means they can be used with mechanical screwdrivers, and they also provide a tighter, stronger bond.

A screw thread can differ in terms of the angle of its ridges, how far they are apart, and how deep the gaps between the ridges are. Nuts, bolts and screws are all examples of threaded fasteners - some have the thread on the outside, and in others - primarily nuts and bolts -  the thread is contained internally.

A screw’s diameter and length are probably the two most common metrics used to tell these fixings apart.

A less common type of screw is the thumb screw. Thumb screws are multipurpose threaded fixings designed to be tightened and loosened by hand, rather than needing tools for installation, such as screwdrivers. This is useful when space is limited and the use of such tools isn’t safe or practical. They can also come in useful where the item in question may need its fixings removed and replaced regularly, for example, if it needs to be detached for maintenance or cleaning.

You may have heard of security screws; these are so named as they are difficult to remove with common tools such as the flat head or Phillips head screwdriver. However, we avoid referring to security screws as being “tamper proof” as many drill kits contain bits capable of removing a variety of security screws.

Now that you know a little more about the humble metal screw, the best place to start when buying is to think about the project you want to tackle.

Decking screws

Their aluminium finish is designed to protect them from the outdoor elements. They will usually feature a Torx head cutout, which makes them a type of security screw, and you will need a Torx head bit in order to install or remove them. Each size of our Perry No.6012 Decking Screw includes the specialised driver needed as standard.

Drywall screws

These sharp-pointed screws are usually double threaded for extra strength as they are designed to hold plasterboard or fibreboard walls to timber studs. The Unifix Black Phosphate is an example of a bugle head screw, designed for drywall, as it is countersunk with a flat head and a concave under-head bearing surface.

Masonry screws

Sometimes called concrete screws, these tough screws are specially designed to be driven into a wall or concrete. They have a wide thread and won’t usually require a wall plug or rawlplug, but usually need a pre drilled hole. The JCP Yellow Zinc Plated Countersunk Concrete Screws have a special corrosion-resistant finish.

Tek Screws

Also called self drilling, these screws don’t require a pre drilled or pilot hole. They pre-drill and fasten themselves in one motion. They are heavy duty and can be installed by hand or using a drill. The Olympic Bright Zinc Plated Hexagon Head Washered Drillers come with a galvanised steel washer which acts as insulation between the fixture and the surface it’s being attached to. It’s well suited for fixing cladding and corrugated sheet metal to steel construction.

Nails

Galvanised nail

Any nail to be used outdoors should always be zinc-plated galvanised nails. Their material and construction makes them resistant to corrosion and damage by the changing weather. The Olympic Twist nails are a popular and robust example in our store.

Roofing nail

Also known as clout nails, these are designed for attaching roofing slates or roofing felt. They’re usually short and thick with a large flat head.

Masonry nail

These are designed to attach wood to tough surfaces like concrete and brick. Masonry nails are ideal for attaching or reattaching skirting boards within a property. Our Don Quichotte Standard Masonry Nails are zinc galvanised for extra durability, so can be used for external applications such as fastening cabling.

Panel pin

This is a general, multi-purpose nail suitable for general carpentry and joinery. It’s easily hammered in due to its small, slim size.

Nail gun nail

These nails come joined together with paper, plastic or wire. Many will be pre-coated in a layer of lubricant or adhesive to help the nail to bond more securely with your chosen fixture and surface.

Nuts and bolts

There is huge variety within nuts and bolts. Most commonly, the M system of measurement is used, indicating sizes in millimetres.

Thunderbolts

A thunderbolt is a type of masonry fixing and is self-tapping, meaning it doesn’t require a pilot hole. These heavy duty bolts are used to attach things like joists and beams onto construction materials such as brick, stone, concrete, marble, blockwork and wood. The Zinc and Yellow Passivated Hexagon Flange Head Thunderbolt has a corrosion-resistant surface, making it suitable for outdoor use.

Carriage bolts

A carriage bolt is most commonly used for attaching wood to metal, but can also be used to attach metal to metal, and even wood to wood. You’ll always need a pre-drilled hole when using a carriage bolt due to the shape of its head - it’s round and therefore not suitable for insertion using a drill. They will often come with a nut and washer for extra-secure fastening. The Unifix Bright Zinc Plated Cup Square Hex Carriage Bolts come with a hex nut and bright zinc plate finish for rust protection.

Roofing bolts

These specialised bolts feature a large flat head, sometimes called a ‘mushroom’ head. Its shape spreads weight further than a standard bolt, making them ideal for use in thin materials without splitting or damaging them. The Unifix Bright Zinc Plated Mushroom Head Roofing Bolts come with square nuts. Their large, flat head makes them ideal for clamping thin sheet metal, plastic and wood.

Hex nuts

The most common type of nut, their name refers to their hexagonal shape. Nuts are almost always used in conjunction with a threaded bolt, but also with threaded screws and studs. It is another type of threaded fastener, providing a clamping force and preventing axial movement. A jam is a hex nut with reduced height, used where space is at a premium. A heavy hex nut is suitable for applications where added grip is required.

Wing nuts

These nuts feature recognisable wing-shaped protrusions used for hand-tightening and loosening on bolts and screws.

Square nuts

This type of nut has four sides rather than six.

Washers and seals

Washers are flat, circular pieces of metal with a hole in the middle, giving them a flattened ‘doughnut’ shape. Their purpose is to add strength or insulation to a join made with threaded fasteners such as bolts or screws.

They come in a variety of sizes, shapes and materials, from the Stainless Steel A2-304 Mudguard (Penny) Washers to the Bright Zinc Plated DIN 125A Washers M10.