LEGISLATIVE ALERT: Denver's Green Roof Ordinance

November 8, 2017

By: Matthew S. Rork and Jessica Alizadeh

On November 7, 2017, voters passed Denver’s Ballot Initiative 1-300 known as the Green Roof Initiative.  The initiative is a city ordinance that will require every building with a gross floor area over 25,000 square feet to have a percentage of the roof dedicated to vegetation or a combination of vegetation and solar.  The initiative passed by a final margin of 54.29% to 45.71% with approximately one fourth of the available electorate voting.  The initiative faced opposition from the development industry, and the Mayor himself, due the mandatory requirements and regulations imposed on building owners.

The green roof requirement does not just apply to new construction.  It may also apply to building additions that increase the gross floor area beyond the 25,000 square foot threshold or existing buildings that already exceed the threshold but perform significant repairs or replacements of their existing roofs. The size of the “green roof” depends on the gross floor area of the building:

Gross Floor Area (Size of Building)  

Coverage of Available Roof Space (Size of Green Roof)

25,000 – 49,999 f2


50,000 – 99,999 f2


100,000 – 149,999 f2


150,000 – 199,999 f2


200,000 f2 or greater



Exemptions are limited and even exempted buildings must provide a cash-in-lieu payment.  Exempted buildings include: buildings with a complete building permit application or site plan application submitted prior to January 1, 2018; residential building or building addition if the height is less than or equal to the greater of four stories or 50 feet; and commercial greenhouses located at grade, temporary structures, or air supported structures. Other exemptions may be available if the owner is unable to provide all or a portion of the green roof coverage.  These exemptions apply if two or more of the following circumstances exist:  the building is used for seasonal purposes and funds are not allocated for off season maintenance; the building is designed in such a way that it would not be possible to meet the requirements of the ordinance; building retains or collects for re-use at least the first .25 inches from each rainfall or 50 percent of the annual rainfall volume falling on the roof; or the building has an Energy Star Building Rating of 80 or higher.  Any exemptions must still provide a cash-in-lieu payment of the construction of a green roof for the reduced or exempted area based on the average actual cost of construction of a green roof.  The ordinance deems that cost at $25.00 per square foot.

The ordinance mandates green roof construction standards relating to such items as the roof assembly, gravity loads, slope stability, fire safety, waterproofing, drainage, plant selection, and a maintenance plan.

The ordinance raises a number of issues regarding its implementation, feasibility in Denver’s climate, impacts on the costs of housing, and insurance coverage issues. 

Barring any further action by the Denver City Council, the initiative will become effective as outlined on January 1, 2018.   However, City Council will have the opportunity to modify the initiative before it becomes an effective ordinance. This includes extending the effective date of the ordinance.  Fairfield and Woods is working closely with members of City Council, trade organizations, and other stakeholders to help ensure that our clients’ concerns are considered in the modifications, and we encourage you to contact us to discuss how this ordinance may affect you or your business.  

Fairfield and Woods, PC is a well respected law firm that has been serving Rocky Mountain businesses more than 80 years. Our real estate team offers a full range of services to the development community to get projects from concept to completion in a range of regulatory environments. If you have any questions or concerns about how the Green Roof ordinance might impact your future or existing development plans, we welcome your inquiries.

This Article is published for general information, not to provide specific legal advice. The application of any matter discussed in this article to anyone's particular situation requires knowledge and analysis of the specific facts involved.

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