In the reconstruction of 23 Rue de Tlemcen in the 20th arrondissement in Paris targets in the renovation were improved energy performance on the existing seven-floor building and to add six new dwellings on the top of the building.
For the architects Lair & Roynette, who designed the extension, the use of wooden building material was an obvious solution from the architectural, structural and thermal perspectives.
The social tenement house in the Rue de Tlemcen in the 20th arrondissement in Paris had 78 dwellings. Six new apartments, in total 300m², were built from wooden elements on the top of the building.
The architects Lair & Roynette designed the additional floor to fit harmoniously with the existing concrete building. They chose to combine two construction systems made of prefabricated wooden elements. The Leno® wall panels and Kerto® LVL roof elements from Metsä Wood were eventually selected.
The walls of the raised structure are made of 115mm Leno® cross laminated panels with external rock wool insulation. The walls are cladded with larch timber boards. The largest panel measured 3.70m x 9.30m which required the use of a special trailer to transport panels vertically.
The roof complex was designed with 425mm Kerto LVL roof elements, insulated with 400mm of glass wool and closed with a 15mm OSB panel underneath.
Wood: A lightweight solution for additional floors
Metsä Wood’s wood solutions are light, so they minimise the loads on the existing building, while still offering bracing against wind load.
The raised structure could not cover the entire length of the building, due to the chimneys on the roof. The Kerto LVL roof elements provided a made-to-measure solution, because the different widths could be adapted around the existing chimneys.
The Kerto LVL roof elements, with their long span, between the load-bearing walls also increase the interior space, because they do not need any intermediate columns nor beams.
However three large Kerto LVL beams, measuring 6 to 7m were installed to create a required slope on one side of the building due to limits set in the Paris urban development regulations.
