MANILA, Philippines—With a rapidly dwindling space for urban dwellers, eco-roof gardens can be the realization of environmentalists’ dream of painting the cities green.

Engineer Andrew Lo, of the Amyda Constructions and Eco-Roofs Inc., told the Inquirer that the trend could catch on in one or two years, admitting that the concept may not be easy to sell because of its unfamiliarity in the country. “But maybe if one or two house owners, even a government agency, start an eco-roof garden, the idea may start to catch on,” he said.

The website for the organization Green Roofs for Healthy Cities states that “green roof or eco-roof development involves the creation of a contained green space on top of a human-made structure.”

The Portland Bureau of Environmental Services, on its website, describe an eco-roof as a living, breathing vegetated roof system consisting of “a layer of vegetation over a growing medium on top of a synthetic, waterproof membrane.”

Utilizing wasted space

Speaking at a forum recently held at the University of the East in Manila, Lo and Munich School of Information Technology ecologist and theologian Christoph Ranzinger discussed the feasibility of planted roofs in an urban setting to fully utilize wasted space.

Lo said eco-roofs or planted roofs could help reduce the perennial problem of flooding in Manila, apart from their other aesthetic, environmental and economic advantages.

“An eco-roof is permeable. Rainwater soaks through the roots so the water does not gush down. It is an advantage in the city because the roots hold the water and it slowly trickles down instead of directly flowing to the sewers,” Lo said.

Working with nature

He added that instead of fighting the elements, it is much better to work with nature and get fresh air in Manila besides.

“Plants are meant to be out there so roofs are protected and they last longer,” Lo pointed out.

Ranzinger explained that one of the earliest examples of eco-roofs is the Hanging Gardens of Babylon or the Hanging Gardens of Semiramis, one of the seven ancient wonders of the world, built by Nebuchadnezzar II around 600 BCE.

Scandinavian countries had sod roofs until the 19th century. These are roofs covered with layers of sod on top of layers of birch bark over sloping wooden roof boards as an efficient means of cold weather insulation.

The concept of growing a modern eco-roof garden caught on in the 1960s and 1970s in Germany as a “means of improving the quality of the urban environment.”

“There is a policy in Munich that every government building has to be environment-friendly so they have solar panels and planted roofs,” the German pointed out, adding that 40 percent of schools, industrial and public buildings in Germany have planted roofs.

Highly urbanized areas in the US, Singapore, Hong Kong, China, and Thailand, have also caught on the concept of eco-roofs mostly for health reasons of lessening pollution and reducing stress.

“We have a big hope to bring green to Manila,” Ranzinger commented.

Primary requirements

The primary requirement for an eco-roof is a strong structure which can withstand the weight of the soil where the garden would be grown.

An eco-roof is composed of a roof deck, a waterproofing layer, a root barrier, a drainage layer, and combined organic materials with soil as the base.

The roof deck could be wood, metal or concrete while the waterproofing layer could be any rubberized material glued to the roof deck. Plastic could be utilized as the root barrier while a coarse, gravel-type material serves as a drainage layer to allow water permeability.

The eco-roof could be intensive or extensive. It is extensive when it is not suitable for foot traffic or occupancy, requires minimal maintenance, and the plants sown are limited to the low-growing types. Intensive eco-roofs are suitable for plant diversity and are mostly found on building rooftops.

An example of an intensive eco-roof is the one found at the SM North Edsa mall, which Lo describes as a “grand scale” of the concept.

Lo admits that installing an eco-roof could cost more than the regular type of tile and shingle roofs but he assured that it is worth the price for its benefits.

Aluminum roofs cost P300 to P500 per square meter, shingles, at P1,000 to P2,000, and tiles are pegged at P3,000 to P5,000 per square meter. An eco-roof cost would go somewhere between the shingle and the tile at P1,500 to P2,500 per square meter and would take several weeks to install.

Lo and Ranzinger first tested the feasibility of an extensive eco-roof in the country on a farm house in Sintang Lupa, Mendez, Cavite.

The house, where a 100-square meter eco-roof is maintained, is owned by Ranzinger and his Filipino wife Agnes. The primary challenge posed by installing the green roof was looking for alternatives to materials used in Munich, Germany, for the eco-roofs which are not readily available in the country.

“We wanted the farm to be as environmental friendly as possible,” Ranzinger explained, adding that he wanted to bring to the country technology or information from Munich that could help the environment and the health of Filipinos in installing the eco-roof.

Prominent project

Lo said there are many who like the idea of an eco-roof but, “it will take a nice, prominent project that people will see,” to convince urban dwellers to go green.

“In the country, somebody has to go first. SM North Edsa mall was a great start but not too grand as that,” he said.

He further emphasized that an eco-roof would be very beneficial for an improved environment, saying, “We are not meant for living in boxes.”