• Welcome to The Building Code Forum

    Your premier resource for building code knowledge.

    This forum remains free to the public thanks to the generous support of our Sawhorse Members and Corporate Sponsors. Their contributions help keep this community thriving and accessible.

    Want enhanced access to expert discussions and exclusive features? Learn more about the benefits here.

    Ready to upgrade? Log in and upgrade now.

Natural Light & Natural Ventilation - Completely Rewritten in the New International Residential Code (IRC)

jar546

CBO
Joined
Oct 16, 2009
Messages
12,996
Location
Not where I really want to be
Here is a summary. Do you see the changes compared to previous cycles?

R325.1.1 Natural Light:
  • Habitable rooms must have glazed openings (windows, skylights, etc.) with an aggregate area of at least 8% of the floor area of the room.
  • These required glazed openings must face directly onto a street, alley, public way, yard, or court on the same lot as the building.
  • Exceptions:
    • Glazed openings can face into an adjacent roofed porch, deck or patio if the longer side is at least 65% unobstructed and the ceiling height is at least 7 feet.
    • Glazed openings can face into an adjacent sunroom.
    • No glazed openings are required if artificial lighting provides an average of 6 footcandles over the room area at 30 inches above the floor.
    • Eave projections are not considered obstructions for yards or courts.
R325.1.2 Natural Ventilation:
  • Habitable rooms must have openable areas to the outdoors with an aggregate area of at least 4% of the floor area.
  • These openings can be windows, skylights, doors, louvers or other approved openings.
  • The openings must provide ready access or be readily controllable by the occupants.
  • Exceptions:
    • Natural ventilation is not required if a whole-house or local mechanical ventilation system meeting certain requirements is installed.
    • Required ventilation openings can open into a thermally isolated sunroom, roofed porch, deck or patio if at least 40% of the perimeter is open to the outdoors.
    • For a sunroom, the minimum openable area between the room and sunroom, and the sunroom to outdoors, is based on the combined floor area.
 
Back
Top