Washington County, MD Noise Ordinances: Construction Hours (2026)

Article 18 of the Washington County Zoning Ordinance governs the "PI" Planned Industrial District, and Section 18.97 sets the noise standards that apply to every use inside it. Subsection (c) lists five categories of noise exempt from the article's sound-level table: transportation vehicles not under the control of the industrial use, occasionally-used safety signals and emergency pressure relief valves, temporary construction activity between 7:00 a.m. and 7:00 p.m., agricultural activities, and emergency generators running during a power interruption. Item 3 is the construction-hours rule: a contractor working inside a PI-zoned industrial park generates noise lawfully, without regard to the decibel table, only while the clock reads between 7 a.m. and 7 p.m.

The identical exemption, word for word, is written into Section 21B.5(b)(3)(iii) for the "ORI" Office Research Industrial District, so both of the county's industrial performance-standard zones share the same twelve-hour construction window. Once work continues past 7 p.m. or begins before 7 a.m., the activity loses its exempt status and is measured against the maximum permitted sound levels in Section 18.97(b): 55 decibels continuous and 60 decibels impact at a residential property line, 64/70 at a commercial line, and 70/80 at another PI-zoned lot line.

The Zoning Ordinance does not carry a separate, general countywide construction-hours rule for residential or commercial zones outside these two industrial districts; the 7 a.m. to 7 p.m. window is specific to PI and ORI performance standards. A site plan for any principally permitted or special-exception industrial use, required under Section 18.101, must show compliance with these noise standards before Planning Commission approval.