Preventing Damage to Home Additions
The building code does not tell a contractor how to attach an addition to the main house. Contractors will put in enough nails to make sure the addition does not fall off but will rarely look to see if the addition will separate from the main house in an earthquake. Nor do building inspectors check to see how earthquake resistant this connection might be. They have no code to follow so the building inspector will pass anything that looks reasonably effective in keeping gravity from separating the two.
Floor to Floor Connectors
The purpose of Floor to Floor Connectors is to make sure these two floors do not separate. Floor to Floor can be made of steel bolts, large screws, special hardware known as Hold Downs, or custom made wood connectors designed on site as circumstances require.