Do you need to pre-drill for coach screws?
In softwood you can usually drive them straight in. In dense hardwoods you should drill a pilot hole first. It stops the timber splitting and keeps the head from shearing off under load. If the screw feels like it's fighting you, back it out and drill the pilot a touch deeper.
What size pilot hole should I drill?
A good rule of thumb is a pilot hole roughly 70% of the screw's shank diameter for hardwood, and a bit less for softwood. So a 6.0mm coach screw wants a pilot around 4mm in oak or beech. Match the drill to the plain shank, not the thread. When in doubt, test on an offcut first.
What socket size fits a coach screw?
These have an external hex head, so you drive them with a socket, a spanner or a ratchet. The 6.0mm diameter takes a 10mm A/F socket. Larger diameters step up to bigger sockets, so check the head across the flats before you start.
What is DIN 571?
DIN 571 is the German standard that sets out the dimensions for traditional hexagon head coach screws. It's the classic heavy-duty woodscrew profile. When a screw says DIN 571, you know the head size, thread and length all follow that spec, so sizing stays consistent across brands.
Can you use coach screws in masonry?
Yes. Drill the hole, tap in a nylon plug sized to the screw, then drive the coach screw home. They bite into hardwood, softwood and brick this way. For solid, reliable fixings into masonry, always use the right plug rather than driving the screw into bare brick.
What are coach screws used for?
They're the go-to for heavy jobs. Think timber-to-timber joints on decking, pergolas and fence posts, bolting down joist hangers and brackets, or fixing gate ironmongery. Anywhere a standard woodscrew would strip out, a coach screw holds fast.