Prefab City A compendium of strategies for prefabricated building techniques in urban environments
Site Placement Strategies On-Frame Modular
chassis
set module on piers
There are two main strategies for placing modular
Off-frame construction (see below) is commonly
buildings on to a site. On-frame construction (see
used for multi-story buildings. The module is
above), also known as mobile homes, is limited to
placed onto the back of a flat-bed truck for
single story structures. Modules are placed on a
shipment, and is craned into its site upon arrival.
chassis, hitched to a truck, and brought to site.
The modules can be stacked according to local
The chassis is lowered onto a set of piers and
zoning and codes, as well as the structural
detached from the truck. The chassis and wheels
integrity of the system. Off-frame systems are
are left beneath the module, making the structure
typically viewed as permanant.
detach chassis
temporary in nature
Off-Frame Modular
flat-bed truck
strap module to crane
place module on foundation
INTRODUCTION DETERMINANTS
add skirting DEPLOYMENT
anchor module to ground
PRECEDENTS
CONTEXT
craning sequence
anchor module to foundation Modular Strategies • 44
Aggregation Techniques There are several ways modules can be aggregated to form a building. Modules can be
Non-attached
Semi-attached
Solo
Framework
Field
Field joint
not attached, semi attached, or attached as seen in the diagrams to the right. Here are several examples of how modules can be aggregated within the different levels of attachment. The examples listed are existing aggregation techniques in their simplest form. The ability of modules to be stacked and shifted is reliant on their structural integrity. Different construction methods will allow for smaller or larger cantilever dimensions and variable building heights. The height of modular buildings is also reliant on local zoning codes for specific materials
Puma City, to the right, is a great example of aggregated modules where one can actually see the aggregation technique clearly. Modules oberseve stack : shift relationships as well as mate and bridge.
Attached : Void
Mate
Stack
Void : Bridge
Mate : Shift
Stack : Shift
Void: Bridge
Mate : Turn
Stack : Turn
INTRODUCTION
Attached : Stack
PRECEDENTS
CONTEXT
DEPLOYMENT
DETERMINANTS
Attached : Mate
Modular Strategies • 46
Mechanical Systems Modular Building Parts As the number of modules in a modular building increases, the complexity by which they are attached also grows. A solo module arrives ready for use, and must only be tied into the foundation. As more modules are introduced there is a system by which their mechanical components are connected. Stacked modules require shafts, similar to that of standard
in-site foundation
buildings, to carry mechanical lines. Large buildings with high volume HVAC and plumbing
typical module
interstitial module
systems can introduce interstitial modules to allow lateral movement of systems in between stacked modules.
Mechanical + Modular Connections
solo module
adjacent modules
stacked modules
mechanical systems
shipping container mechanical units
stacked : adjacent modules
individual container mechanical box Modular Strategies • 48
INTRODUCTION PRECEDENTS
CONTEXT
electrical connection
DEPLOYMENT
shaft space
DETERMINANTS
Shipping Container Connections
Definition and Factors + Transport and Location Defining Density on Demand The creation of superimposed urbanism developed through quick aggregation of compact structures became a perfect model for prefabrication. Not only did it minimize on-site construction but each piece could be shipped around the world to develop communities wherever shelter was needed. This “Density on Demand” can be seen in military bases, emergency relief shelters and temporary housing developments.
Creating Density on Demand There is specific criteria in creating urbanism from prefabricated construction. Being quickly assembled and disassembled to minimize on-site construction takes full advantage of factory prefabrication. This also means the finished product includes little or no site work and a light footprint for a structure that is easily moved around to various geographic locations and climates. Aggregation becomes important to maximize population density within compact limitations if there is any need for downtown city prefab infill.
Factors •
Mobility
•
Adaptability
•
Quick On-Site Installation
•
Light Footprint
The ability to be transported to a site fully constructed, with minimal site work, creates
INTRODUCTION
Mobility + Adaptability opportunities for a potential site, regardless of mobile shelters can be erected on site then moved whenever needed adds a unique aspect to their designs. In the case of the Quonset hut, since it was developed for multiple regions around the world, it incorporated sleds, wheels, chassis or even empty oil drums as pontoons to
DETERMINANTS
location, for instant urbanism. The fact these
maintain the chassis used in transport while occupying a site which can be reused in order to
PRECEDENTS
CONTEXT
move the building to a different location.
DEPLOYMENT
be transported. Mobile or HUD code homes
Density on Demand • 70
Construction On-Site Installation The amount of time spent with on-site construction has a significant effect on implemention strategies. Instant urbanism is automatically tied to its connection with the earth, the amount of on-site earthwork involved and the permanence of those connections. The Quonset Hut and Fema Trailers are two examples that minimize sitework and on-site construction to
Wood Frame House
create efficient instant urbanism. Sitework is able to proceed in parallel with the prefabrication process so when the materials arrive on site there is a minimum amount of work to prepare in order to receive the structure. The Quonset Hut has all of its pieces prefabricated on-site and utilizes simple connections in the field for quick installation. HUD code and mobile homes in general are completely prefabricated, the chassis being reused on-site as supports and remaining attached to the unit.
Mobile/HUD Code Home
Installation Time Wood Frame House + foundation - One Month Quonset Hut - One Day Mobile Home - Six Hours (approx.)
Quonset Hut
Density on Demand • 72 PRECEDENTS
CONTEXT
DEPLOYMENT
DETERMINANTS
INTRODUCTION
Connections Light Footprint
Temporary Construction
Aspects which affect the lightness of a footprint are the permanence of the structure and the mobility for which it is designed. One crucial characteristic is the amount of earth displaced upon construction. This raises the question as to where to store or use this extra earth, particularly in
cases of wood frame houses that incorporate
a crawlspace or basement. More temporary buildings like the Quonset Hut and mobile homes end up with little or no displacement other than surface contact creating the perfect opportunity for rapid deployment and installation for disaster relief or other instant shelter needs.
Quonset Hut
Displaced Earth Footprint
Sill Plates
3000sf Wood Frame House w/basement - 9,600ft3 3000sf Wood Frame House w/crawlspace - 3,840ft
3
Minimal Earth Interaction 1000sf Quonset Hut w/Sill Plates - 16ft3 1000sf Quonset Hut w/Slab on Grade - 320ft 1000sf Mobile Home w/Footings - 12.4ft 2
3
Earth Displaced 16 ft3
INTRODUCTION CONTEXT
DEPLOYMENT
DETERMINANTS
Temporary Construction
Quonset Hut
PRECEDENTS
Slab on Grade
Earth Displaced 320 ft3 Density on Demand •
74
Connections Semi-Permanent Construction
Mobile Home
Concrete Piers
Footings
Earth Displaced 37.3 ft3
INTRODUCTION
Permanent Conventional Construction
DETERMINANTS
Wood Frame House
DEPLOYMENT
Basement
Displacement 9600ft3
CONTEXT
Wood Frame House
PRECEDENTS
Crawlspace
Displacement 3840ft3 Density on Demand •
76
Process
Raw Material
Factory Prefabrication
Delivery
Components
On-Site Storage
On-Site Fabrication
Off-Site Storage
On-Site Installation
Delivery
INTRODUCTION Recycled + Relocated
Erection
Military Base
Military Base
Trailer Park
Disaster Relief Trailer Park
Mobile Home Unit
PRECEDENTS
CONTEXT
DEPLOYMENT
DETERMINANTS
Quonset Hut
Recylced + Relocated Density on Demand •
78