Researcher dismisses green roof misconceptions: “Humans can go to the moon, so this shouldn’t be difficult”

A researcher at the University of Helsinki has dismissed common misconceptions about green roofs, stating that their construction should not be overly complicated given humanity’s technological capabilities.

Susanna Lehvävirta, a university researcher, told Yle that green roofs have clearly become more common in Finland and especially abroad, ranging from small waste bins to large rooftop parks on shopping centers that may even include an ice cream kiosk.

In the early 2010s, Finland saw growing interest in green roofs, also known as plant roofs. A Yle article from 15 years ago reported that around 60 green roofs had been identified in the Helsinki metropolitan area at the time.

Despite this, green roof construction in Finland remains modest compared to countries like Germany, where millions of square meters are built annually.

Lehvävirta noted that plant roof technology has progressed, albeit slowly, overcoming initial skepticism about issues such as snow load management and fire safety. She emphasized that Finland has good standards for green roof construction, which follow the same rules as other roofing—ensuring load-bearing capacity, waterproofing, and root protection to prevent structural damage.

“Humans can go to the moon and who knows where else, so building plant roofs shouldn’t be that difficult,” she remarked.

Attitudes toward green roofs vary among municipalities. Lehvävirta said that while some cities, like Vantaa, have made significant strides with clear policies, others struggle even to discuss the topic due to polarized opinions.

Helsinki and Vantaa have established guidelines for green roof construction, with Helsinki’s “Stadin katot elävät” (Helsinki’s roofs come alive) policy and Vantaa’s own plant roof assessment directing development. Smaller cities like Hämeenlinna and Lahti do not track green roof construction and do not mandate them, though they recommend the practice.

Timo Lahti, Hämeenlinna’s chief building inspector, said most residents opt for solar panels rather than green roofs. Mika Kemppainen, head of Lahti’s building and environmental supervision, added that green roof projects in the city have been rare, mostly limited to solutions like carports.

Lehvävirta does not consider green roofs expensive, noting that costs are comparable to other roofing solutions that must account for snow loads or human activity. She stressed that the benefits—such as stormwater management, urban cooling, noise reduction, and biodiversity support—depend on smart design with multidisciplinary expertise.

Research also highlights additional advantages, including urban farming, social cohesion in residential and work environments, and improved well-being through refreshing and calming spaces.