ThePipingMart Blog Fasteners Coach Screw vs Wood Screw – What’s the Difference

Coach Screw vs Wood Screw – What’s the Difference

Coach Screws vs Wood Screws

When it comes to fastening two pieces of wood together, screws are often the go-to option. However, not all screws are created equal. Coach screws and wood screws, for instance, might look similar at first glance, but they serve different purposes and have distinct differences. If you’re wondering which one to use for your woodworking project, read on as we explore the differences between coach screws and wood screws.

What is Coach Screw?

A coach screw, also known as a lag screw, is a threaded fastener used to secure lumber and other materials. It has a tapered shank with sharp threads that bite into the secured material and an unthreaded shoulder against which the head sits. Coach screws are generally made from steel and zinc-plated or stainless steel for corrosion resistance. They can also be galvanized to protect them from rusting.

What is Wood Screw?

A wood screw is a hardware fastener that includes an externally threaded cylinder with a sharp point at one end and a head designed to facilitate the insertion and tightening by twisting with a screwdriver. They combine two pieces of wood by tightly drawing them together and preventing loosening due to vibration or movement. Wood screws can also be used in soft metals such as aluminium.

Difference Between Coach Screw and Wood Screw


The most obvious difference between coach screws and wood screws is their size. Coach screws are significantly larger than wood screws, usually ranging from 50mm to 200mm long and 6mm to 25mm in diameter. On the other hand, wood screws are smaller, ranging from 10mm to 100mm in length and 3mm to 5mm in diameter. The size difference is due to the intended use of each screw. Coach screws are designed to hold heavy timber structures together, such as decking, joists, and fence posts. Wood screws, however, are meant for smaller woodworking projects like cabinetry, furniture, and frames.

Thread Type:

Another difference between coach screws and wood screws is the thread type. Coach screws have a coarse thread that resembles a spiral with a wide angle. The thread is meant to grip the wood firmly and prevent the screw from backing out due to the weight of the timber. Wood screws, on the other hand, have a fine thread that is more tightly spaced. The thread is meant to cut into the wood, creating a stronger hold.

Head Type:

Coach screws have a hexagonal head that requires a wrench or socket to tighten the screw. The head is typically larger than that of a wood screw to accommodate the size of the screw and the weight of the timber. Wood screws, on the other hand, have a flat or domed head with a cross or slot that can be tightened with a screwdriver.


Coach screws and wood screws are made of different materials depending on their intended use. Coach screws are often made of steel for strength and durability. Some coach screws may also be galvanized to prevent rust and corrosion. Wood screws, conversely, can be made of brass, bronze, or stainless steel for their aesthetic value and corrosion resistance.


Finally, cost is another factor to consider when choosing between coach screws and wood screws. Since coach screws are larger and heavier, they tend to be more expensive than wood screws. However, the cost difference is justified by their strength and durability. Wood screws are cheaper than coach screws but may not be as reliable for heavy-duty applications.


In conclusion, coach screws and wood screws may look similar, but they have several differences that make each ideal for specific applications. If you’re working with heavy timber structures, choose coach screws for their size, coarse thread, hexagonal head, and durability. Choose wood screws for their fine thread, screwdriver-friendly head, and affordability for smaller woodwork. Ultimately, choosing the right screw for your project boils down to understanding the differences and selecting the one that meets your needs.

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