Lag bolts are what we use if we need to connect heavy and large timbers like beams to posts.  These lag bolts are used mostly in bridges, railway trestles, and in other structures where timbers are present and used.  The use of lag bolts is also present in masonry.  In this case they are used together with an insert that is called a lag.  Thread of this lag bolt meshes with metal lag and results in secured fastener.

Before you use lag bolts, you need to determine the type that you need.  Stainless steel lag bolts provide high resistant to salt water and moisture corrosion while lag bolts that are zinc-plated provides minimum protection from rust.  After you have determined the type, the next would be to determine the size.  Its length should be able to penetrate first timber and fasten the second.  Line up those timbers that you need to fastened using clamp before you mark and fasten them.  Drill the pilot hole into the timber.  Make it 3/4 the size of the lag bolt’s diameter.  Finally, insert the lag bolt into the hole.  If you are securing timber to masonry, insert to the pilot hole the lag before you insert the lag bolt.  Tighten using a ratchet and secure the timbers.  While the ratchet is fitted on the lag bolt’s head, turn it clockwise until the head’s bottom touches the wood.