Habitable Space: A space in a structure for living, sleeping, eating and/or cooking. Bathrooms, closets, halls, storage areas, and utility spaces are not considered habitable spaces.

Hairline Crack: A very thin crack on a surface; does not constitute a structural issue for a building.

Hard Coat Stucco: A stucco application involving a mixture of Portland cement, sand, and water, directly applied onto a substrate. Also referred to as traditional stucco.

Headwall: The vertical wall that meets the sloping end of a roof. It typically requires specific flashing techniques to prevent water penetration where the roof and wall intersect.

Hearth: The floor within a fireplace.

Hearth Extension: Non-combustible material in front of and at the sides of a fireplace opening.

Heat Exchanger: A component in HVAC equipment that transfers thermal energy from one medium to another.

Heat-Welded: Also referred to as heat-seaming, it is the process of joining and sealing overlapping thermoplastic membrane edges with heat.

Heated Slab: Slab-on-grade construction in which the heating elements are placed within or under the slab.

HEPA: High efficiency particulate arrestance (filters)

Hinge Jam: The vertical side of a door frame where the hinges are attached.

Hinge Stile: The vertical side of the door itself where hinges are attached.

Hip: The external angle formed by the meeting of two sloping sides of a roof.

Hood: A device that directs and captures grease-laden vapors and gases from a cooking appliance.

Hot Water Boiler: A type of heating system that heats water for the unit’s operation. The water should never reach the boiling point.

Humidistat: A device used to automatically control relative humidity.

HVAC: Heating, ventilation, and air-conditioning system

Hydronic System: A type of HVAC system that uses water as the primary distribution source for heating or cooling.

Hypersensitivity Diseases: Diseases characterized by allergic responses to animal antigens. The hypersensitivity diseases most clearly associated with indoor air quality are asthma, rhinitis, and hypersensitivity pneumonitis. Hypersensitivity pneumonitis is a rare but serious disease that involves progressive lung damage as long as there is exposure to the causative agent.