350 Warren Street

350 Warren Street

By Valentin Stavrev, Elena Osborn, Philippe Barriere

The concept

Proposed upward extension design use the specific feature of wooden structures –their lightness. The specific strength of engineered wood is superior to other traditional building materials. To utilize fully its property the wooden members are combined with other symbol of lightness – a tensile membrane structure. The metal component joints the whole structure in synergistically braced frame to achieve maximum structural efficiency.

The overall shaping of the rooftop is designed to maximize the solar use and to improve aerodynamic properties of the building. The front silhouette resembles a Baroque roof structure framed by the way by wood. 

The site - 350 Warren Street, Jersey City, US

The site chosen for the project Modera Lofts, (former Butler Brothers warehouse) is an excellent example of possibilities of the wooden structures in construction. Facade System applied masonry Architectural style early modernism. Year of construction 1905 with primary use warehouse.
Recently Butler Brothers building has been renovated into 366 apartments and renamed “Modera Lofts”
Architect - Jarvis Hunt, Chicago, U.S.A.


-The wooden multistory structure is a braced portal frame arranged by composite members. Post and beams are composed by Kerto S and Kerto Q beams. The structural lattice matched the module of existing post and beam structure.

-A moment connections made of steel, which are able to bear concentrated loads, make possible a portal action. Prestressed bracing is applied in the longitudinal direction using stainless steel tension rods. 

-The openings of structural grid are fitted with box-type floor panels. They are designed as stressed skin box by Kerto Q sheets and Kerto S beams.

-Intermediate steel frame provide equalization and transfer the loads from roof extension and existing building. 

Environmental envelope

-The primary climatic envelope is a multi-pay ETFE membrane.

-The tensile membrane is supported by curved composite beams. The said beams use modified KertoS technology and are manufactured by predefined curvature to match the shape requirements. The edges of ETFE membrane are clamped by aluminum extrusion that sealed the envelope and transfer tensile loads to structural beams.


External elevators are a particular solution of common problem of large building extensions.


Rooftop extension is in a position to catch more natural light, to collect rainwaters and to facilitate solar energy. Multilayered membrane provides significant thermal insulation only by its air gap.   

City Above the City architecture competition

Plan B : City Above the City architecture competition 

Metsä Wood challenged architects and students around the world to push the boundaries of modern wood building design in the urban environment. Entrants from 40 countries created their Plan B to urbanisation using wood (Kerto® LVL – laminated veneer lumber) as the main material. The task was to design a wooden extension to an existing urban building. The entries were designed to 69 cities worldwide.

Explore the designs