Methods of Measurement for Varying Types of Roofs

• Flat roofs or roofs with a slope less than 3:12. The height of the building shall be the maximum distance measured vertically from the natural or finished grade, whichever is lower, to the top or ridge of a flat, mansard, or other roof with a slope of less than 3:12.
• Roofs with a slope from 3:12 to 7:12. The height shall be measured vertically from the natural or finished grade, whichever is lower, to a mean height between the eave point of the ridge of a gable, hip, gambrel or other similar pitched roof. The ridge of a gable, hip, gambrel, or other pitched roof shall not extend over five feet above the maximum height limit.
• Roofs with a slope of 8:12 or greater. The height shall be measured vertically from the natural or finished grade, whichever is lower, to a point one-third (1/3) of the distance up from the eave point of the ridge. There shall be no limit on the height of the ridge. Chimneys and other appurtenances may extend up to a maximum of two (2) feet above the ridge. Eave point is defined as the point in the roof plane of a structure or building which intersects with the exterior wall surface.
• Chimneys, Antennas and other Appurtenances. Antennas, Chimneys, flues, vents or similar structures shall not extend over ten (10) feet above the specified maximum height limit, except for roofs with a pitch of 8:12 or greater, these elements may not extend more than two (2) feet above the ridge. Water towers and mechanical equipment shall not extend over five (5) feet above the specified maximum height limit. Church spires, bell towers and the like architectural projections, as well as flag poles, may extend over the specified maximum height limit.
• Exceptions for buildings on slopes. The maximum height of a building's front (street facing) facade may extend for the first thirty (30) feet of the building's depth.
• Exceptions for areaways, lightwells, and basement stairwells. An areaway, lightwell or basement stairwell of less than one hundred (100) square feet, entirely recessed behind the vertical plane established by the portion of the building façade which is closest to the street, and enclosed on all four sides within eighteen (18) inches of the first floor level shall not be counted towards the maximum permissible height.

There is not a mountain view plane regulation for private residences in the City of Aspen Land Use Code. If a structure is built within the height limitations of the land use code then it may be built. The only places that have preserved view planes of Aspen Mountain are Glory Hole Park, Wagner Park, Cooper Avenue, Court House, Wheeler Opera House, Main Street.