A lag screw is a great choice for any wood project where you need a sturdy, long-lasting fastener. These screws have coarse threads that grab onto the material they’re screwing into, giving them a high load-bearing capacity. They’re often used to secure large wooden structures like doors, railroad ties and other building materials that require a heavy load-bearing joint.
Lag screws are sometimes mistakenly referred to as lag bolts, but technically the two terms are not interchangeable. Bolts require a nut to hold them in place, while screws can be driven in without a nut. They also have different head types. While wood screws and sheet metal screws are available with multiple head types, lag screws come only in hex heads that are compatible with a wrench or socket head ratchet.
To use a lag screw, first mark the location where the fastener will go. Then drill a hole that’s slightly smaller than the screw’s diameter. Next, insert the lag screw and tighten it with a ratchet or wrench. Be careful not to overtighten the screw, as this can cause it to back out of the hole.
Alternatively, you can install high-strength structural screws in place of lag screws to save time and effort. Structural screws (also known as construction screws) have similar strength and load-bearing capabilities as lag screws, but they’re easy to drive into place with any 18-volt cordless drill with the right driver bit. This makes them a popular, labor-saving alternative to commodity lag screws for many wood-construction applications. lag screws for wood