Cal. Civ. Code § 410.430
Natural Light and Obstructions
Operative Text
(A) The owner shall provide transparent or translucent glass which admits unobstructed light
from the outdoors equal in area to a minimum 8% of the entire floor area in:
(1) Habitable rooms other than a kitchen.
(2) Kitchens which have a floor area greater than 70 square feet.
(B) If any light obstructing structure is located less than three feet from the outside of and
extends to a level above the lower level of the transparent or translucent glass, that portion so
obstructed shall not be included as contributing to the required minimum total glass area.Under 105 Mass. Code Regs. 410.430, residential property owners are required to provide windows or other transparent or translucent glazing in habitable rooms and larger kitchens (those exceeding 70 square feet) that together equal at least 8% of the room's total floor area. The glass must admit unobstructed natural light from the outdoors. If a structure outside the window — such as a wall or fence — sits closer than three feet away and rises above the bottom edge of the glass, the portion of glass it blocks cannot be counted toward meeting the 8% minimum.
Plain English — not legal advice.
Operators subject to 105 Mass. Code Regs. 410.430 generally audit each habitable room and qualifying kitchen to confirm that the total transparent or translucent glazing area meets the 8% floor-area threshold. When calculating compliance, compliant operators account for any nearby exterior structures — anything within three feet of the glass that rises above its lower edge reduces the effective glass area that counts toward the minimum. Careful attention to this deduction is especially important in units with adjacent buildings, fences, or other close obstructions.
General guidance for property managers — not legal advice for your specific situation. Consult an attorney for advice on your case.
Section 410.430 of 105 Mass. Code Regs. 410.000 establishes a right to a minimum level of natural light in habitable rooms and larger kitchens, and a landlord's failure to meet this standard may constitute a violation of the Massachusetts Sanitary Code. Tenants who believe their unit lacks adequate natural light as defined by this provision may consider documenting the conditions and reporting concerns to their local board of health, which is the primary enforcement body for the Sanitary Code. Tenant-rights organizations in Massachusetts can also help residents understand what options may be available when a unit appears to fall short of this standard.
General guidance for tenants — not legal advice for your specific situation. Consult a tenant-rights organization or attorney for advice on your case.
Generated September 30, 2026 — auto-generated, not yet human-reviewed. See /transparency for methodology.
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