Choosing the right screws
(and the screwdrivers to go with them)
There are roughly four billion types of screw, or so you’d think from browsing in a DIY shop. How on earth are you supposed to know which ones you should buy? Even worse, when you’re just about to hang that picture: you rummage through your jam jar of old screws saved from here and there over the years. Which one are you going to use? Your choice is rarely going to be critical but there are a few things to consider. Mainly: thickness (diameter); length; head type.
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There are so many types of screw
Yep, there certainly are. Let’s not go into it all and just stick to what’s relevant here. Get some plain old wood screws. Nothing special. They’re just called wood screws, and they look something like this. Sometimes they come with special features with fancy-sounding names. Sometimes they have a section which doesn’t have any thread along it. Sometimes they have a double thread. Whatever gimmicky selling points they might have, I’d just go for the cheapest (as long as you’re buying reasonable quality).
Sizes of screws
When you buy a box of screws, it’ll be labelled with two numbers – something like this: 4 x 40. The first number tells you the diameter of the screw in mm, and the second tells you the length in mm. (The length refers to the entire length, including the screw head.) You probably want to stick to screw diameters between 3.5 and 4.5 mm. A range of lengths from 30-60mm would be handy.
Head types
There are four main types of screw head:
- Philips;
- Pozidriv;
- Flat / slotted;
- Torx.
Torx heads
Let’s ignore Torx for now. I love these screw heads but they’re not the most common in the UK and, therefore, not the cheapest. I’m assuming you’re reading this because you want to save a bit of money, so let’s try to keep costs down by passing on torx head screws.
Flat / slottedscrew heads
These are what you might think of as a standard or classic screw. They’ve worked just fine, probably for thousands of years but there are better options nowadays.
Philips
Things are looking up. It’s easier to tighten and loosen these than flat head screws, but I find them a bit of a pain sometimes because it’s fairly easy to chew up the heads with your screwdriver.
Pozidriv
Now we’re talking! They look very similar to Philips but, if you examine one carefully, you’ll notice the heads are kind of star-shaped rather than crosses. Take a moment to compare Pozidriv with Philips to see the difference.
I’d recommend always Pozidriv screws every time you need to reach for a new screw rather than using one which might have already been in place.
Top: Philips
Below: Pozidriv
Pozidriv
Now we’re talking! They look very similar to Philips but, if you examine one carefully, you’ll notice the heads are kind of star-shaped rather than crosses. Take a moment to compare Pozidriv with Philips to see the difference.
Screw head sizes
Things get more complicated. On top of all this information, there are different sizes for each type of screw head.
Flat
Use the biggest screwdriver that’ll fit comfortably into the slot
Philips and Pozidriv
Conveniently, these come in three sizes:
Philips – PH1, PH2 and PH3. PH1 is smallest and PH3 is the biggest. There are other sizes but you’re unlikely to come across them. You’ll normally be using PH2.
Pozidriv – PZ1, PZ2 and PZ3. Same sort of idea as Philips. PZ2 is probably the most common.
Which screwdriver?
You need to ensure your screwdriver matches the screw head. Flat heads are quite easy. You might not think it, but Philips and Pozidriv screwdrivers are different and it helps to use the correct one.
Philips screwdriver
Look at the tip closely. It’s just a pointy cross shape.
Pozidriv screwdriver
When you look at the tip carefully, you can see little ribs between each part of the cross.
Screwdrivers compared
It’s quite a subtle difference between the two types of screwdriver. Have a careful look at them side-by-side and, hopefully, the difference will be clear.
Left: Philips
Right: Pozidriv
Something to know
Plasterboard screws and flat-pack furniture screws are usually Philips.
If it’s a + shape screw head, and it’s fairly modern, it’s probably Pozidriv.
If it’s + shaped but you don’t know how old the screw might be, it could be either type.
Takeaways
Get yourself a box or two of Pozidriv screws.
Go for diameters between 3.5 and 4.5 mm, and lengths from 30-60mm.
These screws should require a PZ2 screwdriver.
Take a bit of time to make sure you know how to identify the different screw head and screwdriver types.
