Casa d'en Xifré is a listed apartment block in the heart of Barcelona that consists of 6 buildings. Built in 1837, it was the first apartment block with running water in the city. Its facades and roofs were left untouched until 2019, when works on the Terrats d’en Xifré project were carried out. This rehabilitation project connected the roofs of the different buildings of Casa d'en Xifré through an accessible terrace garden aimed to enhance urban biodiversity.
Design studio MataAlta won the green roofs open competition promoted by the Barcelona City Council and based their proposal for the Terrats d’en Xifré on the ’rewilding’ concept, which aims at reintroducing nature in urban buildings, focusing on self-sufficiency, social interaction and biodiversity. The design included several water ponds, insect hotels, nesting structures, small ponds with fish, composters, all with the purpose of encouraging biodiversity.
Every material was carefully chosen to achieve a low carbon footprint and reduce the environmental impact of the project. First, a detailed structural study of the bearable loads was carried out, taking into account the design of the green roof. A geotextile was installed on top of the original roof structure made of traditional Catalan ceramic tiles, followed by our RubberGard EPDM waterproofing membrane, which was loosely laid on top. Another geotextile was installed on top of the membrane, followed by a drainage layer with an irrigation system.
"Under our feet there are about 20 to 40 cm of soil that contribute to the building's waterproofing, sound and thermal insulation, as well as being the basis for multiplying the biodiversity of a rooftop where there was not even a plant in a pot," says Sergio Carratalá from MataAlta.
The vegetation of the green roof consists mostly of native perennial plants that are aromatic, pollinator friendly, drought and disease resistant and pollution-filtering. The green roof can retain up to 50% of water and the excess is stored in an underground cistern to be pumped up for watering the garden during the hot summer months.
The garden also has work benches that encourage conversation and the meeting of the building’s inhabitants, made up of residents of the city, passengers of a hostel and workers of a co-working space. Sergio insists that everything is benefits, since "the building’s value has increased, it is sound and thermally insulated, it stores water, reduces pollution, promotes urban agriculture and social interaction".
