A deck screw is a fastener that has been purpose-built specifically for fastening decking to the underlying frame. As with most fasteners that are created for specific tasks, they have characteristics that are important for their function. Deck screws have several features that set them apart from other fasteners, one of which is the head. Why do deck screws have square heads, and do all deck screws have square heads?
Deck screws have square heads to increase the engagement of the driver bit in the head of the screw. This enables the screw to be driven in with less torque and less cam out, which will chew up the head of deck screws made from softer, corrosion-resistant metals. Screw extraction is also easier.
The design of the head of the screw is an important feature relating to the purpose of the fastener, not only for ease of installation but also due to the material that deck screws are manufactured from. The square head of the deck screw is only one design feature that makes this type of screw the ideal choice for securing decking.
Why Do Deck Screws Have Square Heads?
A few short decades ago, your choice of drive type for a screw would have been limited to a Philips drive or a standard flat or slot drive screw.
Today, however, we are spoiled for choice for the type of driver head available for our modern fasteners. Even though the square drive head was invented in the early 1900s, the drive type only became popular once it was discovered how to easily manufacture these screw heads and the drive bits required to install the screw.
The square head drive was invented by a Canadian fellow by the name of Robertson, which is why you will sometimes hear square drive screws referred to as Robertson screws.
Why is this important for decking screws in particular? The advantages that square drive heads bring to decking are important for the following reasons.
- Softer material needs less torque. Decking screws are often made from softer metals that are more corrosion resistant than normal steel. Because they are softer, the torque delivered by another driver design may twist the head of the screw clean off. Square drive screws require less torque from the driver to drive the screw in.
- Less cam out. Cam out is when a screwdriver slips out of the head of the screw when the torque is too high or the angle of the driver is incorrect. Repeated cam outs can result in the stripping of the screw head, which can prevent the screw from being driven all the way in or from being extracted. It is important to prevent cam out on deck screws that are made from softer metals.
- Square drives can be used one-handed. The nature of the square drive allows the screw to be placed on the bit of the driver, and it will stay there. This allows the screw and the driver to be operated with one hand to drive the screw into the timber.
- Improved productivity. The one-handed capability of square head screws makes the job go a lot faster, which reduces the installation time for the deck, which can help reduce labor costs for the installation.
- Easier removal. Square drive screws have the same firm fit for both installation and extraction of the screw. This makes the extraction of a square drive screw much easier than many other drive types.
- Longer lasting driver bits. Cam outs not only chew up the head of the screw, but they also inflict damage on the driver bit. The lower likelihood of cam outs with a square head screw means that the square driver bit will also last correspondingly longer.
Do All Deck Screws Have Square Heads?
Not all decking screws have been changed to the square head type. You can still get decking screws with Philips drive heads, but these head types have lost much popularity for decking because of the time factor that they add to the job and the cost factor in ruined screw heads and driver bits.
Philips drive screws that have multiple cam outs can have damaged and sharp edges. Sharp edges on a screw head are not something you want on a surface where people are potentially going to be walking barefoot. Philips drive screws that have been subjected to cam outs are also more difficult to remove.
Thus, while you can still find deck screws with Philips drive heads, they are becoming less and less popular.
Star or Torx drive heads are another up-and-coming drive type in decking screws. Like the square drive head, the star dive head has a much more positive engagement between the head of the screw and the driver. This allows the screw to be driven in with less torque and fewer cam outs.
There are some deck installers who prefer the star or Torx drive head over the square drive, believing that it is superior when it comes to lessening the risk of cam out. They also feel that the fitment of the screw onto the driver bit is easier because of the multiple fitment points on a star drive.
Essentially, the choice between star or Torx drive heads and square drive heads for your decking screws will come down to personal preference. However, you would do well to make your choice of deck screw to have one or the other of these drive types rather than the Philips drive head, or even worse, a slotted drive head.
Square Drive Head Screw Tips
Square drive deck screws are certainly an advantage and make the job of laying down decking go much quicker and smoother. But if you are new to square drive heads, it should be noted that things don’t always go smoothly and according to plan, so we have a few tips for you that will help to make your deck laying task a bit easier.
Square drive screws are not a one size fits all deal. The square slot in the screw head comes in a range of different sizes. This means that you will need to get a driver bit to match the size of the slot in the head of the screws that you have purchased.
Some screw manufacturers will include a driver bit of the appropriate size in the bag of square drive screws, but this is not always the case. So, to avoid a second trip to the hardware store, make sure you have the appropriate size driver bit for the screws!
Driver bits have a nasty habit of disappearing on a job site. Someone changes out the driver bit, puts the square driver bit down, and it becomes lost in the chaos of the construction site. These bits can also be quite small, so they can get lost in the depths of your toolbox or roll off your work-site and drop under the decking, never to be found again!
To cover these pretty much certain eventualities, you need to make sure that you have multiple square driver bits of the appropriate size to ensure you have some spars handy to allow you to complete the job without another trip to the hardware store! The gas you drive out to get there will be more than the cost of the driver bit!
Conclusion
Square head decking screws have certainly brought many advantages to the installation of decking, and they will most definitely be worth their weight in the time they save and the fewer times you have to back a screw out and replace it due to multiple cam outs when you were driving it in.
If you are intending to install a deck, and especially if you are going to do the job yourself, you will be doing yourself a favor by selecting square head screws.
Torx or star head deck screws will also work well as an alternative to square head screws, and your only choice in decking screws should be one of these two types.
Remember to get the appropriate size bit for the screws that you purchase, and don’t only buy one driver bit. Avoid job-site frustration and buy a handful of them! They are not expensive and are certainly less expensive than unnecessary trips back to the hardware store!
References
https://en.wikipedia.org/wiki/List_of_screw_drives#Robertson
https://www.protoolreviews.com/tools/hardware-fasteners/best-deck-screws/3697/