An Ordinance Relative to Single-Stair Building Code Reform in Cambridge
The 1974 Massachusetts Building Code's requirement for two interior stairways in buildings over three stories makes small multifamily housing on narrow urban lots physically and financially impractical. On typical lots of 3,000 to 5,000 square feet, a redundant second stairway reduces usable residential space by 10% and adds $200,000 to $500,000 in construction costs.
Although local zoning cannot directly amend state code, state regulation 780 CMR §104.11 permits building commissioners to approve equivalently safe alternative designs. This policy order establishes a formal framework to permit single-stairway buildings up to six stories when equipped with modern safety systems (automatic sprinklers, pressurized enclosures, and fire-rated doors), unlocking vital "missing middle" housing.