Prefabrication experiments - 337 - Urban mass timber

 

Modular volumetric construction has had inconstant success in the history of prefabrication. Delivering, stacking and setting factory made dimensionally coordinated boxes is in theory a practical idea; building in a controlled environment with specifically regulated production methods concurrently to onsite work has the potential to substantially reduce construction time. Modular volumetric construction has been attempted with concrete, light gauge steel frames, light timber, panelized steel composites and even in glass-reinforced plastics. Every generation and their material lobbyists discover the potentials of mass producing inhabitable containers and piling them to make buildings. Relatively recently another material has entered the modular volumetric market: Mass timber, specifically cross-laminated timber is being used to create streamlined boxes assembled from large sheets of this «hyper plywood material». Panels are produced by pressing, gluing and laminating timber stock in perpendicular fibre patterns to create a composite engineered timber that is stronger than cut timber and comes in large formats not habitually associated with timber structures. 

 

Urban mass timber, a Swiss start-up (2018) was founded to direct the potential of The Swiss Künzli Timber Construction Corporation toward the deployment of their CLT in the modular volumetric sector. The company leverages mass timber as an ecological and carbon responsible way to construct buildings to respond to globalized urbanization and increasing demand for affordable and quickly built dwellings. The mass timber boxes are assembled and then stacked according to predetermined patterns. CLT tall wood building is straightforward usually using a slab and wall framework. Openings for windows and doors or mechanical systems can be numerically cut before assembly. Modular CLT uses the same basic principles but staking box units doubles floor slabs and wall panels. This redundancy is associated with modular volumetric construction, not specific to mass timber and offers potentially greater sound and fire protection. The boxes are dimensioned to comply with transport regulations and work best when juxtaposed and aligned for transmitting gravity loads in the most vertical fashion. This type of system is not proprietary to one company and most CLT producers have the potential to create made to order boxes form their CLT stock panels.

CLT modular volumetric unit

Prefabrication experiments - 336 - U-build

 

Self-build formulas and systems are an integral part of prefabrication history. Moreover, architects and architectural academia have always been fascinated with the design and knowledge sharing potential of generating bespoke houses or buildings from elegantly thought-out kits. Ken Isaacs (Living Structures Matrix, 1954) and Walter Segal (The Self-build method, 1962) explored the D-I-Y theme with the publication of prescriptions and platform systems elucidating the construction of inhabitable objects, houses or furniture from the same modular components. Construction education, the inspiration for the proposals countered industrialization’s hyper-specialization considered as a factor distancing individuals from the social act of home building.  The user, builder or dweller should, with minimal know-how, be directed step by step in the construction process. Democratization of digital fabrication tools is generating a fertile environment for people to get involved with their material culture and built environment. Alastair Parvin’s (Wikihouse, 2011) is a notable example reviving similar attitudes to what Segal and Isaacs proposed federated by current hacker and open-source strategies for leveraging social building knowledge.

 

A recent project established on similar values, U-Build, developed by architectural firm Studio Bark (https://u-build.org) along with structural engineers Structure Workshop proposes a simple flat pack building system for creating a large variety of small housing structures, micro-dwellings or accessory dwelling units. Cut plywood sheets are assembled into prisms, boxes or ribbed surfaces that fit together to shape walls, floors and roofs. Analogous to cinder block construction, the open timber cases are dry stacked and fixed with bolts to form a rigid wall.  The 19mm spruce or birch plywood sheets are divided and cut numerically with a CNC machine into faces fitted with box joints and glued to form the basic units; a five-faced rectangular prism. The timber structure can be insulated and clad in a variety of materials. The modular boxes shape a cavity wall where the case sides are aligned vertically and horizontally to form studs and girts. Wing-nuts and bolts placed in predrilled holes in the case’s perimeter faces hold the structure together. Anchored to concrete foundations or placed over any other stable base material, the structural system is an example of ribbed waffle slab construction applied to wall, floor and roof construction. 

U-build method, from https://u-build.org

Prefabrication experiments - 335 - House 19 mobile studio

Mobile homes or manufactured dwellings, epitomized by early singlewides effectively applied mass production theory to housing. This segment of factory production has been both hailed when discussed in terms of democratization of affordable dwellings and ostracized as poorly designed, built and rot with social difficulties. 

 

The mobile home is particularly interesting as it conceptually links two rival fields and conceptualizations: it strives to be at once a commodity with no particular anchorage and yet function as a dwelling with all the human and social implications of domestic architecture. In the history of prefab, projects that have been able to be successfully applied and appreciated simultaneously in both fields (architecture and manufactured housing) are a rarity. Most are specifically commercial, while others are prototypes of architectural creativity.

 

An example of mobile home principles applied by architects, House 19 designed by Dutch firm Korteknie Stuhlmacher architects in 2003, acts as a moveable studio for resident artists to live and work in the city of Utrecht. Rigorous container dimensions outline a robust and weathertight mass timber structural envelope. The «black box» is structured by cross laminated timber panels reinforced and braced by steel frames. The composite sandwich envelope panels are layered with insulation, weatherproofing, and cladding. 18m long, 4m high and 3.2 m wide, the studio adheres to transport restrictions. A centrally located service core contains all required cooking and hygiene functions and separates night from living spaces. Operable drawbridge elements deploy rich interior and exterior connections not usually associated with manufactured transportable houses. Further exploring these connections, two large, suspended panel doors in the living room and one aligned with the service core create dynamic thresholds.

 

Contrary to conventional mobile homes or container houses these operable spatial components along with a strategically placed vertical skylight over a dining area gives this linear volume an especially airy feel. Two additional small skylights illuminate the bedroom and living room. A large 19 painted on the side of the box reinforces a type of commodification; the unit number intimates a production lot, part of a much larger batch of mobile studios. 

House 19 - mobile artist studio

Prefabrication experiments - 334 - Dieter Schmid House

Polymers have completely integrated and in a sense taken over our material culture. Everything we own is somehow associated to plastics, from the keys on our keyboards, to the cases that guard our smart phones and the countertops where we prepare our food. Plastics are lightweight, durable, malleable, and cheap to manufacture. Plastics are also omnipresent in architecture and construction, employed as pieces, elements in every building system including insulation, sealants, roofing and even polymer-based reinforcing or aggregates for concrete. 

 

The 1950s and 1960s were a heyday for plastics, promising to completely reform our dwellings.  Traditional design iconography would be replaced by the form generating possibilities of molding. Further, the plastic capsule house along with its production methods would make houses commodities free from the vernacular habitual constraints of locus and setting. Prototypes of the plastic house idealized mobility, transportability and eliminated massive earthworks as in masonry and timber-based building cultures. 

 

Matti Suuronen’s Futuro and Walt Disney’s Monsanto House are probably the most famous of these prospective proposals. Other more marginally known prototypes were equally important to the development of plastics as a futuristic material representation applied to house construction.  A notable example was designed by architect Dieter Schmid in 1963 and demolished in 1975.  Lifted off the ground on thin stilts, the habitable prism was composed of glass reinforced plastic composite panels. The dry assembly would make the house a breeze to assemble and eventually disassemble, making it moveable. Inspired by the molding process, exterior wall panels were shaped to enhance, frame and celebrate openings, sills, and windows. The cast stressed skin monocoque included walls, roof and the prism’s undersurface as an idealized continuous envelope. Each modular panel, recognizable in the overall structure, was simply fixed to the adjacent panel. A weathertight strip covered each joint. 

 

An access stair and an extruded reinforced concrete space for servicing the upper volume are the only spatial elements that contact the ground. Even if plastics could reform conventional construction in matters of materials and form, a house’s anchorage to site remains a fundamental factor in its capacity to serve its function. This anchorage was often an incongruous element in the designs for an idealized plastic house.

Dieter Schmid House