A lag screw should be driven in with a hammer to about how far from the tight position, and then seated with three or four turns with a wrench.

A lag screw should be driven in with a hammer to about how far from the tight position, and then seated with three or four turns with a wrench.

• A. 1/4"
• B. 1"
• C. 2"
• D. 2 1/2"

Answer: (A)

When seating a lag screw, you want to balance bite with control. Drive it with a hammer until the screw is just short of being tight, leaving about a quarter inch of travel before the final seating. Then finish by turning with a wrench about three or four turns to draw the screw home. That small gap keeps from overcompressing or crushing the wood and helps avoid stripping the threads. If you go deeper than a quarter inch with the hammer, you risk overdriving and weakening the joint or splitting the wood. If you don’t leave enough margin, the threads may not engage properly, reducing holding power. The three to four wrench turns ensure the screw is firmly seated and the load is properly transferred to the wood.

When seating a lag screw, you want to balance bite with control. Drive it with a hammer until the screw is just short of being tight, leaving about a quarter inch of travel before the final seating. Then finish by turning with a wrench about three or four turns to draw the screw home.

That small gap keeps from overcompressing or crushing the wood and helps avoid stripping the threads. If you go deeper than a quarter inch with the hammer, you risk overdriving and weakening the joint or splitting the wood. If you don’t leave enough margin, the threads may not engage properly, reducing holding power. The three to four wrench turns ensure the screw is firmly seated and the load is properly transferred to the wood.