Md. Code, Land Use § 20-509

(a) Subject to subsections (b), (c), and (d) of this section, by local law, the legislative body of a municipal corporation or governed special taxing district may impose an additional or stricter building requirement than is required by a State, regional, or county unit that exercises zoning or planning authority over the municipal corporation or governed district if the authority is exercised in addition to the State, regional, or county zoning or planning authority. (b) (1) Subject to paragraph (2) of this subsection, a building requirement adopted under this section: (i) shall be imposed for: 1. the protection of the public health, safety, and welfare; or 2. the preservation, improvement, or protection of lands, water, and improvements in the municipal corporation or governed special taxing district; (ii) may regulate only the construction, repair, or remodeling of residential buildings with four or fewer dwelling units, including single–unit houses, duplexes, triplexes, quadplexes, cottage clusters, townhouses, and similar buildings, and their accessory structures, as it relates to: 1. fences, walls, hedges, and similar barriers; 2. signs; 3. residential parking; 4. residential storage; 5. the location of buildings and structures, including setback requirements; 6. the dimensions of buildings and structures, including height, bulk, massing, and design; and 7. lot coverage, including impervious surface; and (iii) shall apply without regard to housing type. (2) A building requirement adopted under this section for residential buildings with two to four dwelling units: (i) may not be more restrictive than a building requirement adopted under this section for a single–unit house; but (ii) may be less restrictive than a building requirement adopted under this section for a single–unit house. (c) Before adopting a local law under this section, a municipal corporation or governed special taxing district shall: (1) hold a public hearing; and (2) at least 30 days before the public hearing, transmit a copy of the proposed local law to the county council. (d) A local law that a municipal corporation or governed special taxing district adopts under this section shall provide a procedure for a waiver from the strict application of the building requirements. (e) By local law, a municipal corporation or governed special taxing district may enact an additional or stricter commercial sign regulation than is imposed by the State, the Commission, or the county.