It is very important that you use the right size and kind of fasteners to install your ledger board.  Your deck will depend on the load carrying capacity of these screws or bolts to support hundreds of pounds and prevent the deck from ripping away from the house.  The most common method is to install ½” lags with washers or carriage bolts with washers.  You will usually need the length to be at least 4”-6" to penetrate through the 2x ledger board, the house sheathing and into the internal house framing.  Never counter sink bolts.  This will significantly weaken the ledger board.  In a ledger board application, a ½” x 4” lag bolt was tested to provide 180 lbs support of allowable shear load per screw.  Many types of structural screws are available from various fastener manufacturers. 

Be sure that whatever fastener type you choose is approved for your intended use and will be strong enough to satisfy the loading.  The fasteners must also be compatible with pressure treated lumber to prevent corrosion.  To be on the safe side always check with your local building inspections department. If you want to use a fastener that the inspector is unfamiliar with you may be required to provide an engineering report from the manufacturer that provides technical proof that your fasteners are appropriate for ledger board applications.  Building inspectors use guidelines laid out in The National Design Specification (NDS) for Wood Construction to evaluate design values for structural connections (nails, bolts, screws etc.)   Most decks are built with too few ledger board fasteners to handle the IRC load requirements.  However, decks rarely fail at the house because it is unusual for a deck to realize the actual maximum design loads