What is a Coach Screw?


A coach screw is a strong, heavy-duty wood screw with a hexagon head, perfect for heavy timber projects.  They differ from standard multi-purpose wood screws, which are smaller and suited for lighter wood applications.


Also known as


Lag screws.


Why use Coach Screws?


When you’re working with heavy timber, particularly in landscaping, engineering or construction, coach screws are essential. You can use them to:



  • Join two pieces of heavy wood.

  • Secure metal to wood.

  • Fix timber to masonry, like concrete and brick.

  • Build outdoor furniture and structures, such as benches, tables, swings, decking, playground equipment, timber frames and animal shelters.


When working with woods like oak or cedar that contain high sap levels, stainless steel screws are the best option. Zinc-plated screws, although widely used, may corrode in sap-rich woods.


Coach Screws: How they work


Choose the correct screw length for your project, drill a pilot hole, place a washer (a penny washer works well) over the hole to prevent splitting, and then drive in the screw using a spanner or wrench.


For fixing into concrete, brick or stone, we recommend using a plastic plug such as our Fischer DuoPower plug before inserting the screw.


Features and specifications



  • Material: Zinc coated (our bestseller) or stainless steel.

  • Sizes: Four diameters - M6, M8, M10 and M12. Lengths range from 20mm to 200mm.

  • No need for nuts or bolts.


Need high-quality Coach Screws?


Buy Unifix coach screws from Fastco, with free delivery on orders over £30.*


Shop now on our website, email us at sales@fastco.co.uk, or call 01270 252326.


*Restrictions apply. Check our delivery page for details.