s 5 Prohibition of back-to-back houses
(1) Notwithstanding anything in any local Act or byelaw in force in any borough or district, it shall not be lawful to erect any back-to-back houses intended to be used as dwellings for the working classes, and any such house shall for the purposes of this Act be deemed to be unfit for human habitation: Provided that nothing in this section shall prevent the erection or use of a house containing several tenements in which the tenements are placed back to back, if the medical officer of health for the borough or district certifies that the several tenements are so constructed and arranged as to secure effective ventilation of all habitable rooms in every tenement. (2) This section shall apply to any house commenced to be erected after the third day of December, nineteen hundred and nine, except that it shall not apply to houses abutting on any streets, the plans whereof were approved by the local authority before the first day of May, nineteen hundred and nine, in any borough or district in which, on the third day of December, nineteen hundred and nine, any local Act or byelaws were in force permitting the erection of back-to-back houses.