Lag Bolts

Lag bolts are used to attach equipment or steel shapes to wood structures. The size and location of the anchors can be determined from construction drawings.

• The edge distance is 1½ times the bolt diameter.
• The spacing between bolts is 4 times the bolt diameter.
• The end distance is 7 times the bolt diameter.

Step 1: Mark the location of the lag bolts

Lead holes and clearance holes are not required for lag bolts that are 3/8” or smaller. If the lag bolt is smaller than 3/8”, go to Step 4.

Step 2: Drill a clearance hole

Drill a hole with a drill bit the same size as the shank of the bolt. The depth of the hole is the same as the length of the unthreaded shank that will extend into the wood.

Step 3: Drill a lead hole

Drill a hole with a drill bit that is 60 to 70% of the diameter of the shank of the bolt. The depth of the hole is the same as the embedment depth of the bolt.

Step 4: Move the equipment or steel shape into place

Step 5: Drive the lag bolt in with a wrench

You may use soap or other lubricant on the lag bolt.

DO NOT USE A HAMMER TO DRIVE IN LAG BOLTS.

Step 6: Tighten the bolt

Hand-adjust the lag bolt where there is firm contact between the lag bolt and connected metal components. Tools may be used to bring the lag bolt and metal components into contact until the components are snug tight.