Montgomery County, VA Outdoor Lighting: Light Trespass & Shielding (2026)

Montgomery County regulates spillover light as one of the "dangerous or objectionable elements" its performance standards exist to prevent, alongside noise, vibration and air pollution. The rule applies to every permitted and special-use-permit use in the county, whether the use is principal or accessory, with one carve-out: lawful agricultural operations are exempt from the performance standards entirely. 25 footcandle ceiling above background light levels, measured either at the boundary between a commercial or industrial use and an abutting residential use, at the lot line of any residential district, or, in residential and agricultural districts, at the lot line of any adjacent lot.

In the C-1 conservation, A-1 agricultural and R-R rural residential districts, the code adds a second requirement: lights must be shielded so the direct glare of the bulb itself is not visible past the property line, regardless of the footcandle reading. Projects that require a site development plan under Sec 10-53(3) have to submit a lighting plan to the Zoning Administrator demonstrating compliance before approval; the Zoning Administrator can waive that submission for minor projects expected to have limited impact on adjacent properties. Illumination levels are measured with a photoelectric photometer that mimics the human eye's spectral response, following the standard luminous efficiency curve adopted by the International Commission on Illumination, so a homeowner or business cannot dispute a reading on the basis that a different instrument would read lower. Determinations that require technical equipment beyond what county staff normally carries can trigger an outside expert review under the chapter's enforcement provisions.