K-style gutters have a flat back and a molded front that looks a bit like crown molding, and they’re the usual choice on houses today. Half-round gutters, shaped like a pipe cut in half, use round downspouts and often suit older, traditional homes. They hold less water at the same width, so a half-round may need to go up a size.
In the Church-Cherokee Streets, Forest Hills and Kennesaw Avenue districts, Marietta’s preservation ordinance treats two kinds of gutter work as minor. One is swapping in new gutters where the old ones hung, at the same scale. The other is adding gutters to a house that had none. Neither needs a Certificate of Appropriateness, but the districts’ guidelines still ask that new gutters be designed and placed to keep damage and visual impact low.
The downtown district is stricter. Its guidelines ask owners to keep historic gutters and, when they’re too far gone, to replace them with gutters of the same look, color and size. Exterior work there generally needs a Certificate of Approval, which the city’s Historic Board of Review grants, so settle that before ordering.