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Creative City Solutions added ten sustainable homes on top of the apartment complex at Arent Janszoon Ernststraat 700 in Amsterdam. This optopping not only created additional housing but also enabled a major upgrade to the entire building. Constructed with sustainable materials like wood, five of the new homes achieved an A+ energy label. Solar panels were installed to generate green energy directly where it’s consumed.
In addition to sustainability upgrades, €400,000 worth of improvements were made, including a new elevator, entrance, and security features. Residents also benefit from an additional €300,000 to invest in further enhancements. This project combines housing expansion with sustainability, contributing to a greener city and lower living costs.
This mixed-use scheme for General Projects replaces an existing car park with a seven-storey extension featuring a steel frame and cross-laminated timber (CLT) slabs. Designed for sustainability, it retains most of the original building fabric, including masonry facades and concrete cores, saving 255 tonnes of embodied carbon.
The new building will offer over 236,000 square feet GIA of office space with glazed terracotta cladding, planted terraces on each level, and an energy-efficient design targeting BREEAM Outstanding certification. CLT slabs minimise carbon emissions across the structure.
The former telephone exchange from 1923 on Kamerlingh Onneslaan, built in the Amsterdam School style, is being transformed into a unique space for living and working. With its classic corridors and original details like stained glass windows and historic doors preserved, this project honours the building's heritage while optopping one whole new floor.
The project won the private competition in 2017. Creating extra living and working spaces while respecting the historic architecture from the Amsterdamse School. This blend of modern design and Amsterdamse craftsmanship reimagines a dynamic place where history and modernity meet.
In this extensive refurbishment of the 1970s office building at 8 Bleeding Heart Yard (20-23 Greville Street), the majority of the original structure was retained, focusing on circular design. The refurbishment spans 35,566 square feet, with renovations to the basement, ground, and first floors, which have been adapted for retail and restaurant use. Additionally, a two-storey public colonnade was added to enhance the building's functionality and accessibility.
The project has been recognised for its commitment to retrofitting and reuse, receiving accolades such as the AJ Retrofit & Reuse Awards 2024, Civic Trust Awards 2024, and New London Awards 2023. The primary structural system for the addition uses Cross-Laminated Timber (CLT).
Stiff and Trevlilon’s design revitalises a 97,000 sq ft (27,432 m²) building through an extensive refurbishment. A standout feature of the project is the new roof pavilion, framed with Cross-Laminated Timber (CLT), and clad in a distinctive scalloped brass. This roof extension is complemented by a raised and cranked curtain wall system with bespoke brass and bronze cladding, forming part of a steel framing system (SFS).
The design, which includes two additional floors, showcases an energy efficient approach, winning accolades such as BREEAM 'EXCELLENT', ATA Awards for Office, Future Projects, and Stakeholder Engagement in 2021. The primary structural system is made from CLT.
The Spanish studio Agora Arquitectura has transformed an abandoned brick structure into the foundation for an elevated wooden house on the outskirts of Barcelona. Aptly named House on a Brick Base, the design pays homage to the site’s traditional construction methods through the brick base, while the wooden structure symbolizes the present and future.
Within the building’s exterior shell, two perpendicular brick walls form a T-shape, creating interior divisions and supporting the wooden structure above. External brick staircases connect the various levels of the house, seamlessly integrating with the old brickwork. Following these stairs, one encounters a 100-year-old olive tree that serves as a welcoming focal point near the main entrance.
The architect constructed the wooden house from prefabricated cross-laminated timber (CLT) and clad it with whitewashed cork. A raised garden was also introduced beside the house. The timber frame features large, uniformly placed windows that flood the interiors with natural light, creating a serene atmosphere.
Inside, a striking spiral staircase immediately captures attention. It serves as a vertical connection between the old and new sections of the house, extending up to the second floor. A large skylight above the staircase ensures abundant natural light reaches the ground floor. The interiors are further enhanced with whitewashed plywood walls and wooden ceilings, lending a rustic yet contemporary feel.
The project involved adding a new floor and a roof terrace to the building, offering exceptional views of the West End. Alongside these additions, upgrades were made to lifts and common areas.
Designed for BREEAM Excellent certification, the extension utilised a hybrid cross-laminated timber (CLT) and steel framework, combining sustainability with structural efficiency. These improvements significantly enhance the building's environmental.
The redevelopment of a 1930s former furniture warehouse in Hackney preserves the essence of the original four-storey structure while adding a new extension and new office space on the top floor. CLT panels and glulam beams are used for the new addition.
The top-up of this Hackney building features a 1-storey addition along with a roof extension, both supported by a primary structural system of CLT panels and glulam beams.
The Gramophone Works in London reimagines a 120-year-old structure on the Grand Union Canal as a multifunctional office space. Phase 1, completed in 2018, included refurbishing and redeveloping the Saga Centre warehouse. Phase 2 expanded and extended the Old Gramophone Works building upward into a six-storey timber-framed office.
The upward expansion of Gramophone Works utilised CLT and glulam as the primary structural materials. The lightweight glass-clad extension ensures environmental efficiency, making it one of Europe’s largest wood-framed office buildings.
Holbein Gardens showcases a transformative refurbishment. The project focuses on achieving ambitious embodied carbon targets through pioneering material reuse, including structural steel salvaged from demolition sites. This is one of the first UK projects to adopt this innovative approach.
To minimise carbon impact, the building incorporates Cross Laminated Timber (CLT) slabs supplied by Eurban, integrated with reused steel for the rooftop framework. These measures, combined with the sustainable upgrades, earned the project accolades including BREEAM Outstanding, WELL Platinum certification, Nabers 5-Star rating, and WiredScore Gold.
Technique, completed in 2022, offers 74,000 sq ft of premium office space across six storeys. The project adapted two historic buildings in Clerkenwell, reducing carbon emissions and waste through an innovative design. By reusing much of the existing building fabric, the project saved 1,709 tonnes of CO2 and diverted 2,560 tonnes of waste from landfill.
The Technique office project is a sustainable redevelopment in Clerkenwell, where 3 additional storeys were added using Glulam columns and CLT floor slabs. Through careful analysis, the team retained much of the original structure.
Technique, completed in 2022, offers 74,000 sq ft of premium office space across six storeys. The project adapted two historic buildings in Clerkenwell. The extension features Glulam columns and CLT floor slabs, emphasizing sustainability in its construction.
The Technique office project is a sustainable redevelopment in Clerkenwell, where 3 additional storeys were added using Glulam columns and CLT floor slabs. Through careful analysis, the team retained much of the original structure, saving significant carbon emissions and reducing waste.
This project integrates renewable structural materials like cross-laminated timber (CLT) and glued laminated timber (glulam). With no downstand beams, the structure allows adaptable subdivisions for tenants of varying sizes. The central atrium promotes networking and fosters a sense of community, reinforcing its multifunctional purpose.
The rooftop extension, built using CLT and glulam, prioritises renewable materials while achieving exceptional spatial flexibility. This design won the AJ Retrofit Award 2019 and underscoring its innovation and sustainability.
The transformation of Prins Hendrikkade 48 is also known as The Nook Amsterdam. The original layout of the building has been revealed, forming the basis for the flow, function, and use of the space. Restored inner courtyards now serve as the heart of the building, surrounded by large, open, and flexible workspaces where the authentic building walls provide the fundament.
The project breathes new life into the building by integrating a modern lift and stair core around the restored courtyards. The rooftop extension, crafted with a dynamic interplay of glass and perforated metal. This contemporary intervention respects the original architectural style while adding a new layer of character and identity.
This arts centre reimagines its original 1960s structure by retaining concrete shop units and adding two timber-frame storeys. The extension features affordable workspaces and a light-filled studio, supporting community education and creative programs.
Sustainability drives this project, with timber-framed storeys reducing embodied carbon by 70%. The reuse of existing foundations showcases how thoughtful design can blend innovation and conservation.
This project carefully restored a historic building, creating 400 sqm of Grade A workspaces that balance open-plan and private areas, blending contemporary design with preserved original features.
Through meticulous investigation into its historic fabric, the design transformed a once-dilapidated building into a functional and beautiful space.
This innovative project features a copper standing seam extension, built atop a steel transfer structure at the fourth floor. The design cleverly integrates CLT (Cross-Laminated Timber) panels for both floors and load-bearing walls, seamlessly blending modern materials with traditional architecture. The lecture theatre seating area follows the natural curvature of the structure, supported by exposed glulam beams and CLT panels.
This structural approach eliminates the need for secondary support structures, creating a visually striking and functional space. The project has received multiple recognitions, including the New London Awards 2021 for Learning and Structural Awards 2021 for Structural Transformation. It also achieved BREEAM ‘Excellent’ certification, highlighting its sustainability and innovative design.
This 2021 office project involved a vertical extension using a hybrid steel-and-timber structure on a steel-framed building with masonry elements. Minimal foundation strengthening was needed, thanks to the use of lightweight materials and the removal of existing heavy screed finishes.
The project combines Portland stone and red brick in its primary structural addition, preserving the building’s embodied carbon while expanding usable office space.
In the heart of Amstelveen, the UpMountain project turns a bold idea into reality: building 45 luxury apartments with 50 parking spaces atop a parking garage. The stepped design and generous outdoor spaces give the complex the appearance of a mountain village, offering a unique living experience in the city centre of Amstelveen.
Located at the southeast corner of Stadshart Amstelveen, UpMountain replaced the former V&D department store with a stunning transformation. The original structure was stripped, redesigned with a new façade, and expanded with a parking garage. The roof of the garage became an unexpected building site, paving the way for an innovative housing concept. A brilliant example of maximising urban potential.
The Bournemouth Office Development, designed by Footprint Architects, revitalises the existing concrete structure with a modern optopping clad in timber.
The new timber-clad rooftop optopping introduces a warm, contemporary appearance, supported by the existing concrete frame. The addition highlights the importance of adapting existing structures while prioritising sustainable materials and innovative design.
Fenix I in Rotterdam is a bold and iconic addition to the city, combining 45,000 m² of mixed-use spaces with a striking steel table structure built through the historic 1922 Fenix warehouse. This redevelopment celebrates its heritage while introducing 212 loft apartments above the century-old monument.
The mixed-use program includes the Cultural Cluster, featuring various Arts School. Built on the Open Building principle, the loft concept is exceptional in scale, showcasing Fenix I’s technical and architectural brilliance as a defining landmark for the city.
The Nubiola building in Barcelona’s Eixample district has been reimagined as a modern workspace. The renovation maintains original features like vaults, pillars, and shutters while introducing a steel primary structural system to support the new design.
The project combines the legacy of the 20th century with an updated internal steel framework and exterior enhancements. It transforms the building into a versatile space that bridges past and present.
This pioneering project in Pamplona adds three new floors to an existing building using pre-manufactured modular construction. These modules, including two duplex penthouses, are installed via cranes, creating housing in a prime location while minimising construction disruption.
The renovation includes significant upgrades to the existing building, such as a modern ventilated façade for energy efficiency, renovated entrances, and new lifts.
York house revitalised an existing concrete frame by adding modern extensions and refurbishing all floors to meet the needs of contemporary businesses. The design incorporates a CLT structure at the roof level, clad in a perforated aluminium screen, and a rear timber extension supported by a steel frame.
With sustainability at its core, the project won awards including. Its combination of a CLT roof extension and timber rear addition, supported by self-supporting brick walls and a steel frame, enhances functionality while maintaining environmental ambitions.
EDGE Olympic in Amsterdam features a wood-based optopping with laminated columns and beams left exposed. The extension is designed with a full glass façade to create a contrast with the existing structure. To manage solar gain, the building features a Dutch climate façade on the east and west sides, utilising a cavity between internal shading and glass.
This optopping, made with sustainable materials, plays a key role in EDGE Olympic’s journey towards net-zero energy. The addition of this top floor, alongside the integrated technology and circular design, maximizes natural resources, optimizes energy use, and enhances the building's overall performance
This steel-frame rooftop extension in Roosendaal offers an innovative solution for urban expansion. The project adds five new apartments to a former monastery, demonstrating how steel-frame construction can meet the growing need for inner-city housing. The method provides several advantages over traditional building techniques, including lightweight construction, faster building speeds, and easy integration with existing installations.
The extension’s lightweight design and prefabrication opportunities allowed for a quicker, more sustainable build, all while maintaining flexibility in design. This method also ensures that the construction process is weather-independent, making it an ideal choice for complex urban projects in city centers.
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La Casa Por el Tejado reimagines unused rooftops as sustainable living spaces. By merging historic building rehabilitation with pre-fabricated steel and wood modules, it delivers modern penthouses.
The Aragó 277 project in Barcelona added two completed modular penthouses to an 1885 Eixample building. The building’s historical essence is preserved while using pre-fabricated steel and wood units.
Located in Barcelona’s Quadrat d’Or, Aragó 334 is a historic 1875 corner property reimagined by La Casa por el Tejado (Joan Artés Pérez, Oriol Cugat Canals). The project introduces two new floors constructed with steel and wood modules, adding three high-end apartments while preserving the old style of the building.
The updates includes a new lift, hall, and façade with pre-industrialised modular additions. Located steps from Mercat de la Concepció and Passeig de Gràcia, the design balances tradition and innovation both presence in the architecture culture of Barcelona.
The Selfridges project, led by David Chipperfield Architects, introduces a one-storey retail extension atop the iconic building. The new addition is constructed using structured steelwork and cross-laminated timber (CLT).
This retail extension exemplifies modern design and sustainability, using structured steelwork and CLT for the construction. Designed to enhance the iconic Selfridges building, the project prioritises low-carbon materials and innovative engineering for a refined architectural addition.
The Hoover Building’s renovation transformed this Grade II* listed landmark into a residential building with 66 homes. The project involved meticulous repair of the façade and the introduction of prefabricated timber structures.
This award-winning project—recognised with BREEAM Awards 2019 (Home), RICS Awards 2019 (Design Through Innovation), and Structural Awards 2018. The prefabricated timber extension exemplifies innovative, sustainable construction.
Lingotto Ontwikkeling transformed the historic complex W99 along the Amstel in Amsterdam by adding two new storeys to the main building on Weesperzijde. This optopping not only provided space for additional homes but also revitalised the entire structure, seamlessly blending historic restoration with contemporary design.
The new levels were constructed using modern, sustainable materials, while the existing building was upgraded with green features, including a shared rooftop garden. Residents benefit from bespoke interiors and outdoor spaces, creating a perfect balance between heritage and modern urban living.
At Wibautstraat 80-86 in Amsterdam, the transformation of the Jan Bommerhuis was completed in 2017. The project expanded the building with three additional floors, bringing it to nine storeys in total. These top layers, finished with sleek aluminium cladding by Alusystemen Montage B.V., seamlessly combine modern design with the historic character of the original structure.
Once home to the Amsterdam University of Applied Sciences, the building now offers 162 rental apartments, storage spaces, and a parking garage for 68 cars.
Located at 285 Marina Street in Barcelona, this project elevates a multi-family building by two floors, each containing three apartments. Designed with industrialised modules, the new floors stil contain the character of the historic structure.
In addition to the modular extension, the project includes the full rehabilitation of the communal areas, staircases, and ventilation wells, as well as the installation of a new lift. The redesign introduces folding aluminium doors on the street side and Alicante blinds on the interior side.
This project features a creative transformation of an existing building by adding a new office floor and roof, replacing the former plant level. With Heyne Tillett Steel engineers, the extension leverages pre-fabricated CLT to form a dramatic double-height office space with a mezzanine and angled rooflights, adding 80 sqm of modern workspace.
The new exposed plated steel staircase, suspended from the structure above, extends to the rooftop, complementing the pre-fabricated CLT addition. This innovative design exemplifies a sustainable approach while maximising the functionality of the existing structure.
Enric Granados 69 in Barcelona showcases sustainable innovation with two new homes added atop an existing multifamily building. Using Senda, a proprietary environmental evaluation tool, the project incorporates lifecycle-focused design and eco-friendly materials like cedarwood and expanded metal for facades.
The expansion features a rooftop terrace, natural light optimization through extended courtyards, and solar collectors for hot water. Residents enjoy unique spaces with terraces, sunlight, and views, harmoniously integrated into the historic urban fabric.
The London Road, Kingston project transforms an existing office building into 23 modern private homes, including 15 one- and two-bedroom flats. A striking engineered timber Cross Laminated Timber (CLT) rooftop extension adds eight duplexes.
This office-to-residential conversion exemplifies urban renewal, combining eco-friendly materials with functionality. The CLT rooftop extension highlights the versatility of engineered timber while minimising environmental impact.
Borough High Street revitalisation enhances the building's exterior with modern materials, including corten steel cladding on the rooftop, and new windows. Key to the design is the exposed RC waffle slabs, complemented by a steel frame and CLT slabs in the rooftop extension.
The rooftop optopping, constructed with a steel frame and CLT slabs, adds a contemporary touch while reducing structural weight. The project exemplifies thoughtful adaptation of existing structures and has been recognised with awards.
The project includes the addition of a penthouse, top-floor refurbishment, and common area upgrades to house La Casa por el Tejado's.
The updated design maximizes space with a sleek penthouse addition, improved facilities, and an elevator for a seamless modern workspace.
This refurbishment and extension of a post-war building balances functional requirements with an expressive design. Strict daylight criteria shaped a dramatic angular roof and wall structure, mirrored in the side elevation that projects over the pavement as if “plugged in” to the original façade. Prefabricated Cross-Laminated Timber (CLT) forms the primary structure.
Prefabrication with CLT ensured rapid execution and minimised impact on the surrounding area. The project’s innovative approach earned recognition with the RICS London Awards 2017 (Highly Commended) and the British Homes Sunday Times Award.
Doctor Letamendi 29 in Barcelona adds two luxury penthouses, modernizing the building with upgraded flats, common areas, and a new elevator.
The project transforms the building, offering improved spaces and amenities while preserving its architectural charm.
This project involves the construction of five houses within an existing building, including three on the lower floor and two on the upper, alongside a complete rehabilitation of the structure, including the facade, lobby, stairs, patios, and facilities.
The new upper floors enhance the original building, with lightweight modules minimizing disruption and reducing construction time.
The project involves adding two penthouses to an existing building, along with a full refurbishment of common areas and installation of a new elevator.
The additions and upgrades aim to increase the building’s appeal, offering modern living space in the popular city center of Barcelona.
The project utilises steel and wood modules to add a penthouse for housing, refurbish common areas, and install a modern elevator system.
This innovative design leverages lightweight materials to minimise disruption, creating a modern living space with improved accessibility in city center of Barcelona.
The project added two penthouses and three flats using steel and wood modules, creating a sustainable three-stage top addition for modern housing.
Alongside the new additions, common areas were refurbished, and a modern elevator was installed to boost accessibility.
The Hotel Vincci Gala is a luxurious 4-star establishment located in a protected 19th-century palace in Barcelona's Eixample district. It balances traditional architecture with modern design, preserving its historic facade, marble staircase, and floors while incorporating contemporary elements.
Designed by Stefan Richter and Gregor Mertens, the hotel features 78 rooms, a bar, restaurant, meeting rooms, and terraces across 4,600 m². Its striking interior uses gold tones and metal accents, contrasting with original stone and marble materials, reflecting both elegance and innovation.
This new-build project in Barcelona's Left Eixample offers centrally located apartments and penthouses near cultural landmarks like the Hospital Clínic and Escola Industrial.
The design incorporates pre-industrialized steel and wood modules, ensuring a faster, efficient, and eco-friendly construction process.
The renovation of four homes atop an existing building incorporates steel and wood modules, seamlessly blending modern design with the original structure. Shared spaces like the hall and patios are also rehabilitated, ensuring continuity with the building's architectural identity.
Using pre-industrialised steel and wood modules, the project reduces construction time to minimise disruptions to residents.
The Queens Court rooftop extension, designed by Wells Mackereth, introduces two duplex penthouse apartments atop a 1960s residential block in St. John’s Wood. The project creatively utilised air rights to develop nearly symmetrical apartments, each measuring approximately 3,400 sqft with expansive terraces.
Completed in 2012, this residential development added two storeys to the existing structure, demonstrating innovative use of urban space. The penthouses combine luxurious interiors with outdoor terraces, maximising light and views in a prime London location.
Located in the heart of Bucharest, Metropolis Center benefits from easy access to major city landmarks like Calea Victoriei and Kisseleff Park. Metropolis Center in Bucharest is a standout office building, blending heritage with modernity.
The optopping integrates seamlessly with the original architecture, and with 1,500 sqm of piazza space, it offers tenants a vibrant area for outdoor interactions.
With 48 luxury maisonettes completed in 2008, this development is just one example of optopping's established presence in Rotterdam's housing market.
The novelty of optopping today is its focus on making the other apartments more sustainable and lower the energy bill of residents. These are objectives with which optopping can be the means to achieve them
The Hanover House development involved the refurbishment and roof extension of a Victorian Grade II-listed warehouse, transforming it into a residential building. A three-dimensional, self-supporting truss system made of KLH engineered timber directed roof loads onto the original external walls.
Completed in 2008, this residential project integrates spatial design with structural innovation. The roof extension, constructed entirely of solid cross-laminated timber (CLT). The result is a blend of Victorian architecture and modern engineered timber solutions.
Amsterdam’s compact city initiative aims to densify urban spaces, and the IJdoornlaan housing complex in Amsterdam-Noord is a prime example. Two of five identical housing blocks were transformed to include two lightweight additional stories. These stories feature rental apartments accessed via external galleries and elevators integrated into sleek eleven-story towers. The project also included full renovation of existing apartments, enhancing the entire complex’s functionality and appeal.
The project added 78 homes while requiring just 5,000 square feet of open space—a model of efficient urban densification. It exemplifies modern, sustainable design with an eye for community needs, blending innovative materials and thoughtful integration of public and private spaces.
A former office complex on Joan Muyskenweg in Amsterdam has been transformed into residential units. This challenging project was completed as a design & build assignment for housing corporation Vesteda, with project management by Objectum and design by Ector Hoogstad Architecten. The original four office buildings were combined into two residential blocks, each optopped with three additional storeys, creating a total of 191 new apartments.
The design features a "warehouse-style" aesthetic with brickwork layers and suspended steel balconies. The rooftop extensions are characterised by the use of lightweight materials, both in colour and structure, inspired by the softness and lightness of clouds. The apartments range from 50m² on the original floors to approximately 110m² on the newly added top levels
Kroonpark 68 in Arnhem is located in a building of the 'flat dwelling (other)' type, with a mezzanine floor subtype. During the latest measurement, the property was registered with an energy label of A, one of the highest energy-efficient ratings in the area.
The address Kroonpark 68 has the status 'residential unit in use,' and the building it is located in holds the status 'building in use.' This indicates that the property is actively occupied, offering both functionality and energy efficiency in a prime location.
A unique project is underway: a rooftop extension on an existing residential building. Using lightweight modular wooden units insulated with biobased materials, this optopping ensures quick, clean, and efficient construction with a reduced ecological footprint and improved indoor climate
By cleverly utilising existing staircases, the extension is integrated with minimal disturbance to current residents. This innovative approach not only adds much-needed housing but also enhances sustainability for the entire building.
The Oveja Negra building in Poblenou is envisioned for a vertical extension using a steel structure, a concept that aims to preserve the existing building while adding new space efficiently.
The project, still in conceptual stages, proposes a combination of steel construction and prefabricated modules to create a new upper volume, while preserving the integrity of the original building and minimising construction time.
The Barcelona Urban Tech Hub (BUTH) is an innovation centre by IAAC, dedicated to urban technologies and sustainability. Located on Carrer de Ávila, it brings together start-ups, researchers, and entrepreneurs to foster the digital and ecological transition of cities, using engineered timber as a primary building material for optopping.
Collaborating with Tech Barcelona, COAC, and Barcelona Global, BUTH will incubate local and international talent, offering training, scholarships, and a focus on zero-emission cities. The building features engineered timber as example of sustainable innovation and pioneering curiosity.
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