Using Coach Screws
The coach screw is a highly popular fastener type. As a fastener, coach screws find application within many different timber and masonry projects, as well. In this article, we will have a look at the various ways to use coach fasteners, and the different coach fastener types.
How to Use a Coach Screw
Timber
All coach screw types need a pilot hole. A general purpose drill bit, like a twist drill bit, is ideal for creating a pilot hole. You need to do this before fastening coach screws into place, as it prevents the wood from splitting. Ideally, you would want to use a wood drill bit to create the pilot hole. They are slightly different from metal drill bits, as they have a point on the end, which prevents them from slipping out of the correct position.
As a general rule, the diameter of the pilot hole must be half the diameter of the coach screw when using soft wood. On hardwood, you want the diameter to be three quarters. As an example, an 8mm coach fastener needs a 4mm pilot hole for soft wood, and it needs a 6mm pilot hole for hard wood.
When you use coach fasteners on timber, try to use a washer. This allows you to avoid embedding the screw head into the wood once fully fastened. This also makes it much easer to remove the screw when needed. Another option is using a flanged coach screw, which has an integrated washer built into its head.
Masonry
You can use coach screws to fix heavy items to brickwork or masonry. If you are doing so, you will need to drill the hole using an SDS drill bit. Also be sure to use a wall plug with the coach screw. This ensures that any heavy object fixed to the wall is as secure as possible. The wall plug you use for the coach fastener must be the same diameter and depth as the hole you just drilled.
Coach Fastener Materials
Most Coach fasteners use steel in their construction, with different types of finishes available for them.
Stainless Steel
Stainless steel offers excellent corrosion resistance. As such, they serve as an ideal fastener for outdoor use. Coach screw types with this finish are best used in Cedar and Oak in particular. These particular types of wood contain acid and other chemicals, which corrode metal.
Zinc Plated
Zinc plated coach screws provide moderate corrosion resistance. As such, they are best suited to outdoor use in dry environments.
Organic Coating
Green organic coating provides weather resistance. For this reason, screws with this finish are ideal for outdoor use. They are ideal for projects such as decking, or sheds.
Passivated
“Passivated” refers to a process in which the coach fastener goes through a two-part deep cleansing process. This removes any iron and other contaminants from the screw surface.
Hot Dip Galvanised
These coach fasteners have a thicker zinc coating than zinc plated ones. This provides them with even more improved corrosion resistance, ideal for outdoor use.
