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# §27-750 Area of Ventilating Openings

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Ventilating openings in all habitable rooms or spaces shall have a free openable area of at least five percent of the floor area of the room or space ventilated and where there is an enclosed or partially enclosed balcony or space above a setback complying with section 27-733 of article three of this subchapter the ventilating openings shall have a free openable area of at least five per cent of the combined floor area of such room and portion of the balcony or space directly adjoining and in front of such room. Each required ventilating opening shall have a minimum openable area of six square feet. Where fresh air is furnished in any habitable room or space by mechanical means supplying a minimum of forty cfm the free openable area of the openings may be reduced to one-half of the above requirements but not less than five and one-half square feet in aggregate. In all occupiable rooms or spaces, the free openable area shall be used to calculate the index for ventilation (section 27-753 of article seven of this subchapter), which shall determine the minimum requirements for supplementary mechanical ventilation.

### Related Code Sections

§27-750 Light, Heat, Ventilation and Noise Control, Area of Ventilating Openings

*Ventilating*

*openings*in all habitable rooms or spaces shall have a free

*openable*

*area*of at least five percent of the floor

*area*of the room or space ...

1203.3.1 Interior Environment, Openings for Under-Floor Ventilation

The minimum net

*area*of*ventilation**openings*shall not be less than 1 square foot for each 150 square feet (0.09 m2 for each 13.9 m2) of crawl-space ...1203.4.1 Interior Environment, Openings for Under-Floor Ventilation

The net

*area*of*ventilation**openings*shall be not less than 1 square foot for each 150 square feet (304.8 mm2 for each 45 720 mm2) of crawl space ...1203.3.1 Interior Environment, Openings for Under-Floor Ventilation

The minimum net

*area*of*ventilation**openings*shall not be less than 1 square foot for each 150 square feet (0.09 m2 for each 13.9m2) of crawl-space ...1203.4.2 Interior Environment, Exceptions

are not required if

*ventilation**openings*to the interior are provided. The total*area*of*ventilation**openings*is permitted to be reduced to 1/1,500 ...