Revise and replace section as follows:
Exception: A townhouse consisting of only three townhouse units with an aggregate area of less than 12,000 ft2 shall be permitted to use an NFPA 13D system.
For the purposes of this subsection, the aggregate area shall be the combined area of all stories of the townhouse and firewalls shall not be considered to create separate buildings. Aggregate area shall include garage areas, basement areas and finished habitable attic areas. Unfinished habitable attic areas, attic areas and crawlspace areas shall not be included in the aggregate area.
Exception: An automatic sprinkler system shall not be required where additions or alterations are made to existing townhouses that do not have an automatic sprinkler system installed.
780 CMR, ch. 51, ch. 3, R301, 301.1, 313.1