SPAX1/4" x 3" Interior Hex Head Structural Wood Lag Screws Powerlags Hex (500 EA) Bulk Pail Bit Included Heavy Duty

Used about 300 of these to sister 2x6s to old 2x4s in a roof and ceiling system from an old 1950s house. NO issues with splitting, usually worked great going in to the wood, but you DO have to push a bit or stab it in.#1 TIP: Use an "impact driver". It looks like a drill, but it behaves very differently. When it reaches a certain amount of torque it starts "hammering" as it turns and that makes all the difference in the world to drive it into old hard lumber. If you can't buy or borrow an impact driver, use a socket set and ratchet, NOT a standard drill because you won't have enough torque to get it in all the way with a regular drill.