Final answer:
In a residential real estate transaction for houses built prior to 1978, the necessary addendum is for disclosure of information on lead-based paint hazards as required by federal law, due to the risks associated with lead paint that was widely used before it was banned.
Step-by-step explanation:
When engaging in a residential real estate transaction for a house built before 1978, the specific addendum that must be used is the Addendum For Seller's Disclosure of Information on Lead-Based Paint and Lead-Based Paint Hazards as Required by Federal Law. This requirement is due to the risk of lead-based paint exposure, which was commonly used in homes prior to its ban in 1978. The statistics provided by the U.S. Environmental Protection Agency indicate that a significant portion of homes built before 1978 likely contain lead-based paint, which poses health hazards, especially when the paint deteriorates or during renovations. Therefore, this federally mandated disclosure helps protect buyers and ensure that sellers provide necessary information about potential lead-based paint hazards.