In November’s general election, Denver voters approved the so-called green roof ordinance, which goes into effect on January 1, 2018. Under the ordinance, all new buildings in the City and County of Denver that are 25,000 square feet or larger, any additions to existing buildings that cause the building to equal or exceed 25,000 square feet, or a roof replacement on a building in that is 25,000 square feet or larger, must incorporate green roof technology into their design. A “green roof” is one that incorporates growing vegetation, and the percentage of the roof that must be green will vary depending on the size of the building. Buildings between 25,000 and 49,999 square feet will be required to have twenty percent of their roof surface green, while that percentage will increase to 60 percent on buildings over 200,000 square feet. The initiative will also allow a portion of the green roof requirement to be satisfied by the installation of solar panels, as long as at least 30 percent of the roof continues to be “green.” Residential buildings with a height of less than four stories or fifty feet are exempt from the green roof requirement, and in some instances the Denver Planning Board may approve exemptions to this requirement, although a cash-in-lieu payment equal to $25.00 per square foot the roof area that would otherwise need to be green must be paid by the applicant.

Although well intentioned, the ordinance is likely to have many far-reaching and unintended effects on Denver’s built environment. Many existing buildings needing roof replacements will require substantial modifications in order to accept the additional weight of soil, plant material and irrigation equipment on their roofs. Denver’s windy and arid climate will make continued maintenance of a green roof difficult and increase water consumption. Many building owners will likely be surprised when the next major hail storm damages their roof and they find that the green roof requirement must be followed in connection with their repairs.

Due to the short time period between the November election and the January 1 effective date, the Denver Building Department and Community Planning and Development are working feverishly to develop forms and procedures implementing the Ordinance. Projects that have submitted a complete Site Development Plan application or a roof permit application to the City by December 31 will be exempt from the green roof requirements. Building owners and managers who may need to apply for a roof permit in 2018 are encouraged to submit their applications to the City before year’s end, even if they are not sure that the work will go forward.

More information regarding these efforts, and a copy of the Ordinance can be found here on the City’s web page.