New Year Ushers in Stringent Green Roof Regulations for Denver

New Year Ushers in Stringent Green Roof Regulations for Denver

Rudy Verner and Yasmina Shaush


A ballot initiative which divided Denver environmentalists and the business community went into effect on January 1, 2018, requiring structures with at least 25,000 square feet of gross floor to construct green roofs. A green roof is constructed to allow vegetation to grow and includes structures such as rooftop gardens. Although not the first initiative of its kind in the country, Denver’s green roof ordinance is being billed as the strictest. Following the lead of San Francisco and Chicago, which also have green roof ordinances, the Denver ordinance goes beyond requirements for new construction to include existing structures over 25,000 square feet which require roof repair.

The Denver Green Roof Initiative began as a citizen-led effort by Brandon Rietheimer, aimed to improve sustainability, encourage urban agriculture, and improve air quality. The group cited Denver’s rising temperatures and poor air quality as concerns for the starting the initiative. The city ranks third in the nation for highest heat island, meaning temperatures in the city are several degrees higher than in surrounding areas. Last year, the state capital ranked eleventh in the nation for worst ozone particulate pollution. Green roofs, voters hope, will help alleviate these effects.

Denver Mayor Michael Hancock and business groups opposed the ballot initiative, spending $250,000 in opposition advertising. However, the initiative passed last November with approval from 54.3% of voters.

All green roof construction requires a permit to be issued by the Community Planning and Development Department. The new regulation provides a percentage of roof space which must be devoted to green roofing based on the gross floor area of the structure, ranging from 20% to 60%. There is an exemption for residential buildings less than four stories tall. Unique from other ordinances, the Denver regulation includes a provision requiring structures built prior to January 1, 2018, which require roof repair, to comply with the green roof regulations. The ordinance also allows builders to offset some of the green roof requirements through the installation of solar energy panels.   

In accordance with Denver ordinances, the City Council may not alter or repeal the green roof ordinance for six months. According to The Denver Post, in anticipation of repeal or change of the ordinance, the Denver Department of Public Health and Environment is forming a review task force comprised of supporters and opponents of the initiative, representatives from Denver Water and Xcel Energy, and green roof experts.