

Excl. VAT
Coach screws, also known as lag screws or lag bolts in some regions, are heavy-duty fasteners that combine features of both bolts and wood screws. They are characterized by their robust construction, having a hexagonal head that can be driven with a wrench or socket, and a threaded shank designed to bite deeply into wood or other materials.
These fasteners typically have a coarse thread pattern that extends partially up the shank, while the upper portion remains unthreaded. This design allows the screw to firmly grip the material it's driven into while maintaining high tensile strength. The threads are specifically designed to resist pull-out forces, making them ideal for applications requiring strong, permanent connections.
Coach screws are commonly used in heavy timber construction, outdoor structures, and wherever substantial holding power is needed. Common applications include:
They're usually manufactured from high-grade steel and often come with protective coatings such as zinc plating or hot-dip galvanizing to prevent corrosion, especially when used outdoors. Available sizes typically range from small 5/16" diameter screws to much larger 3/4" variants, with lengths varying from a few inches to 12 inches or more depending on the application.
When installing coach screws, it's standard practice to pre-drill a pilot hole to prevent the wood from splitting and to make installation easier, particularly with larger diameter screws. The pilot hole should be slightly smaller than the screw's root diameter for optimal holding power.
We stock a variety of lengths of 12 mm mild steel cup SQ coach bolts which are supplied with an M12 nut . Our square plate washers are sold separately and can be selected below. Please select the length you require from the images below and the quantity. You can place an order for any of our bolts and fixings and collect from our trade counter making it even easier to get the materials you need. If you need help or can't find what you are looking for then please contact our friendly and experienced team on 0118 975700.
No customer reviews for the moment.
Some of the areas that we service Swindon, Cheltenham, Southampton, Bath, Portsmouth, Northampton, Watford, Slough, Selsey, Hythe, Winchester, West Sussex, High Wycombe, Basingstoke, Newbury, and Bracknell.
Login