Par. 1. - In second and third class tenement houses hereafter erected and existing tenement houses hereafter altered, stair halls other than those required to be of first class construction may be enclosed with wooden stud partitions; provided that such partitions are filled in solid the full height between the studs with brick, terra cotta, gypsum blocks or other filling material approved by the commissioner, all to be laid in mortar and both sides of partition and soffit of stairs plastered with three coats of cement plaster on metal lathing. All openings in these partitions are to be protected as mentioned in section thirty-five of said chapter five hundred and fifty.

[1921, c. 289, sect. 9.]