Firstly what is the definition of a screw?
“a short, slender, sharp-pointed metal pin with a raised helical thread running around it and a slotted head, used to join things together by being rotated so that it pierces wood or other material and is held tightly in place”.
Screws are made from different materials and choosing the right one is essential for your project.
Zinc plate or gold passivated
These types of screws have a thin protective coating and aren’t as hard wearing as other kinds of screws, so they’re used primarily for indoor use or protected undercover outdoor areas.
They’re not generally suitable for use with treated pine or areas directly exposed to the elements.
Galvanised
Galvanised screws have a tougher coating than zinc plate screws and are therefore great for outdoor use, or for use in areas exposed to the elements.
Galvanised screws have a tougher coating than zinc plate screws and are great for outdoor use.
You can get galvanised screws in a few different grades, ranging from outdoor to severe corrosive areas.
Stainless steel
Mainly used for outdoor areas and can handle mild marine, urban and rural environments.
Stainless screws also come in different grades ranging from mild outdoor to extreme marine environments including saltwater coastlines or underwater environments.
When it comes to size screws are measured in length and gauge (thickness). You can get screws in many different gauges and lengths so it really depends on what you need the fix together. The larger the gauge the thicker the screw is. Screws can be measured in metric and imperial so choosing the correct measurement is essential to ensure it suits your driver and pilot hole.
There are also a huge selection of different screw heads that can be chosen.
Some of the more common heads are:
- Slot
- Philips Head
- Pozi Drive
- Hex
- Fearson
There are many other head types that can be used as security fixings.
Screws can also be self-drivers or tappers, this means the screw will bore its own hole without the use of a pilot hole. Other screws may need to have a hole drilled and the head counter sunk.
Choosing the right screw for your job is important. The wrong screw can lead to corrosion and eventual break down of the fixing.
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