The interlocking system adopted by the Lock-BUILD Group was initially developed at the University of Hawaii, USA. Later development took place at the Asian Institute of Technology, Bangkok, Thailand. During these periods, totalling some twenty years, the system evolved into a fully fledged international class building system with extensive construction projects throughout Southeast Asia. The design and technology of the interlocking system also evolved from simple one-story rural cottages to complex multi-story urban developments. The Lock-BUILD Group was founded in 1992 and employs architects, engineers, builders and planners, some of whom helped to create and develop the original interlocking system. The company was created to efficiently deliver Lock-BUILD projects to clients in Thailand.


The Lock-BUILD Group is capable of servicing a wide spectrum of projects: from a singlefamily residence to large scale urban developments and from a chemical plant factory to a greenhouse. Many construction projects are also be Turnkey operations. The following services are provided using either the Lock-BUILD system or conventional construction methods.

  • Design/Build of Lock-BUILD and conventional construction.
  • Professional services include Architectural design, Project feasibility studies, Environmental planning, Quantity surveys and Cost Estimating, and Mechanical and Structural Engineering
  • Construction Management and General Contractor services.


LockBUILD, an elision of ‘interlocking building’, describes a system of assembling buildings utilizing a modular based, mechanical and grout method of interlocking to fabricate and assemble, on site, structures that primarily rely on locally available raw building materials.  Rather than bolting, welding, nailing, screwing and gluing together or pouring concrete into complicated wood molds encountered in conventional building construction, interlocking reduces construction time and complexity, enabling projects to be completed more quickly.  Unskilled, inexperienced labour, tutored to carry out simple tasks in fabricating and assembling building elements on site, eliminate agent, retailer, middleman and manufacturer markups and reduce or eliminate handling, packaging and delivery costs.  Combining marginal labour costs, a simplistic construction system and a novel assembly method assure the lowest possible cost of construction.


Every irreducible item, whether fabricated on site, outsourced from a manufacturer, or purchased off-the- shelf from a store, to be integrated into a LockBUILD construction project, is called an Object. Generic Objects are non-specific representations of a class or group of like objects that, when modified to perform specific functions, assume their own unique identity as Objects. Objects can be combined with or be inserted into an infinite variety of Object assemblies to perform useful tasks that simplify the assembly of a LockBUILD structure. Objects are broadly categorized as either System or Architectural Objects.

Architectural Objects, that may also include structural elements, are derived from six generic Objects: Masonry Objects, Panel Objects, Deck and Roof Objects, Stair and Ramp Objects, and interlocking Lintel Beam Objects that bridge, link and support walls, stairs, ramps, floors and roof decks. An interface between the building super-structure and its load bearing surfaces or supports, is provided by a modular set of inter-locking steel forms to create Concrete footings, Pile caps and Grade beam Objects, to more quickly complete the untidy, part of the building assembly process.

System Objects are derived from six generic Objects: Electrical Objects, Communication and Control Objects, Water Objects, Waste and Vent Objects, Solid Waste Objects, Heating and Cooling Objects. System Objects, are given a unique identity and are used to make a building System and branch Sub-Systems that, when combined with an appropriate Architectural assembly of Objects will create fully functional buildings with rooms and functional spaces. Electrical, Communication and Control Objects Sub-Systems are pre-assembled into wiring looms. Water, Waste and Vent, Solid Waste, and Heating and Cooling Objects are pre-assembled, using jigs to make a building System and branch Sub-Systems that, when combined with the appropriate Architectural assemblies of Objects, create rooms and fully functional spaces.

Modules are discrete spaces assembled from appropriate Objects suitable for specific functions or human activities that, when combined or nested within another, facilitate the assembly of a LockBUILD structure. Architectural Objects and Modules conform to a mandatory 60 cm Matrix, System Objects do not. Matrix, a dimensioning constraint to ensure that Objects, assemblies of Objects and Modules that make up a complete LockBUILD building will fit exactly together, is based on a cube and is derived from Objects commonly used to enclose a volume namely; walls, roofs and floors. The most constrained of these are Generic Masonry and Generic Panels, because of their small cross-sectional dimensions of 5 cm (2”), 10 cm (4”), 15 cm (6”), and 20 cm (8”) determine the smallest common denominator of 60 cm (2’) in both plan and elevation views. The matrix provides flexibility in planning and designing buildings and, if extended beyond the perimeter of a building to property lines, integrates anciliary structures and hardscape into the uniform design and construction processes.


Conventional construction drawings are freely sprinkled with notations that are frequently redundant, irrelevant or use labourious methods of referral to other drawings on other sheets or layers. LockBUILD eliminates this complexity by using an alphanumeric code called Keycode that completely removes the clutter of all textual notation from the drawing layers, leaving only dimensions and 3D representations of Objects or Modules linked by lines to their Keycodes. In the course of plan making a computer operator/plan maker will, when needed, either create a new Object, assign to it a unique Keycode and place it in the computer LockBUILD Library, or retrieve an existing Object with its Keycode from the computer LockBUILD Library. Attached to each Object will be relevant information such as a description, dimensions, surface areas, constituent materials, installation processes; unit and labour costs, and a short specification that can be accessed via its Keycode or a graphic thumbnail of the Object itself, to retrieve the following information outlined below. Modules when created or retrieved, may also have attached summations of data of all Objects contained in the Module. (See also Chart 1).

A prefix (first 2 digits), that denotes up to 99 phases or stages of construction when each Object is to be or has been placed in a LockBuild building project. This enables advanced scheduling to meet “just in time” site manufacturing or externally sourced Object delivery schedules and for accurate cost control management by sampling comparative costs at specific phases of construction. The UniFormat (next 3 to 4 digits) is used to indicate in what part of the building structure each Object is to be or has been be placed. This enables accurate accounting of Objects in selected parts of the building, such as the building shell, to estimate pre-construction costs and to sample comparative costs of a selected part of a building at specific phases of construction for cost control management. The Master Format (next 5 digits) describes each Object by name, size and surface areas, installation processes, a short description and specification and other relevant data and, by quantifying and costing constituent materials, labour and material costs by phases and final cost of labour and materials, for cost control management.

A suffix (last 3 digits) that identifies up to 999 unique variants of a generic Object. The number of each unique Object required for each phase of construction and the total number of all such Objects in the project. By using current unit cost of materials and labour used to fabricate and place an Object in a building, determine the cost of all similar Objects or Modules at each phase or stage of construction for accurate cost control management, and the total as built cost for all Objects or Modules at the conclusion of construction. The labour input in hours or man-day units required to fabricate and/or install each unique Object, to record labour input during construction phases and at the conclusion of construction. An outline specification for quality assurance, materials, and methods of fabrication, handling, transporting, storing and installation for each unique Object.

Entering into contracts in multi-lingual or foreign countries poses the problem of construction documentation translation into another language. The conventional manner of page-by-page translation of drawings and specifications is tedious and prone to errors and omissions. Instead, a copy of the original Objects and Modules in the LokBild Library is made. All text in the copy is then translated into the new foreign language but all numeric values and the original Keycode are retained. The translated version is placed in the LokBild Library under with same Keycode but with a new title in the translated language. Translated construction documentation procedures remain identical to those of the original language. For firms that carry out projects in multi-lingual or foreign countries, the problem of translating textual notation on drawings and in specifications is quickly and accurately solved.


Tasks that share complementary trades, skills, and materials from both architectural and systems generic groups can be conveniently grouped together to form teams of workers with the requisite number of workers calibrated to conclude the team assignment within a project schedule time limit. Team tasks can be further divided to their irreducible limits so that individual team members can be quickly tutored to execute a simple task needed to carry out their part of the Team assignment. Since Teams in the Inverse Assembly Line must move from Worksite to Worksite to perform their tasks, they require logistical support to carry with them the tools necessary to perform their tasks and to accept the delivery of appropriate off-line sub-assemblies at every Worksite, for placement in the structure.

The three steps of manufacture of sub-assemblies, their delivery to the building assembly line and their placement in the building are each managed by a Team Sub-Captain under the overall management by the Team Captain to assure consistent quality control and accountability. Harmonizing the time that Teams need to complete their assigned tasks at each Worksite with the rate of speed at which Teams can move between Worksites without overlapping or lag time, determines the optimal rate of productivity. By colour coding Teams, team members, tools, containers, machines, and mobile equipment, the delineation of factory work area and storage spaces for materials and stores, reduces anomalies in material quantities losses, errant deliveries, and work delinquency.


The safety of a redundant structural system, inherent in the LockBUILD System load bearing wall method of construction, assures greater structural stability than the potentially critical point loads of conventional post and beam construction, to achieve a simple, safe and intuitive method of construction that combines structure and enclosure in a single operation. By adding the speed and flexibility of computer based techniques, time and cost savings are also extended to include the preparation of 3 dimensional design and construction drawings of pre-engineered, pre-fabricated interlocking LockBUILD assemblies. These are stored and retrieved from an internal computer LockBUILD Library to enable clients to observe and participate in a seamless progression from design to construction drawings that exactly simulate the systematic stages of the LockBUILD building assembly process. Depending on the extent of the accumulated library typologies and the experience of the computer operator/plan maker, design, plans, specifications and construction details of complex multi-story buildings can be completed within hours or days rather than weeks or months.


A computer aided design and drafting (CADD) program creates, for each unique Object and Module, a graphic 3D image depiction on the computer screen drawing layer and assigns attributes that describe the functions, size and material and labour inputs in quantitative, time and cost terms and a short specification that can then be attached to the graphic 3D screen image. Using this data, quantity surveyors can exactly enumerate, at any stage of the drawing process up to the final construction drawings, the number and cost of all Objects to be used in a building project. This implies that, when using a computer to ‘build’ a LockBUILD structure in 3D, each time a symbol instance is placed on a layer of a set of drawings, it will be counted only once. The same Symbol, although viewed in plan, section or elevation views will be counted only once. Specification writers can similarly complete an accurate short specification of all Objects in a building project. Production of design brief, schematics, design development, contract documentation and simulated construction becomes a continuous flow of computer generated graphics, material selections and costs. These may be collated and displayed in real time to answer queries by the client on design or assembly alternatives and to more accurately and much earlier, finalize the design, selection of materials and assembly techniques and to determine final costs.

Through its selective retrieving capability, the computer can prepare reports of Objects and Modules from the computer 3D model drawings of simulated construction at progressive phases from preliminary design to completed construction documentation of the whole or particular parts of a building. The reports will yield the current costs of labour, materials, and project overhead. Compared to conventional manual estimating with its susceptibility to human error, the Object and Module based approach to quantity surveying, cost estimating and construction specifications is capable of very high accuracy.

At the construction stage, linked computers between Head Office and Field Office at the construction site continuously monitor and integrate construction progress by using project planning software, to animate Bar Charts that link together schedules, purchases, and cash flow to make possible real time revisions to project scheduling, account balances and cost control management. (A process LockBUILD pioneered, as an integral part of the LockBUILD design-build process, long before commercial computer applications on Building Information Modeling (BIM) appeared.)


Objects and Modules with their Keycodes and attached data are stored in the computer LokBild Library under their Generic Group name and may be retrieved from the Library by Keycode or a 3D thumbnail graphic image. The selected Object or Module with its Keycode and attached data, when it is dragged and dropped on a drawing layer, becomes a Symbol instance that, although it may appear again on other drawing sheets or layers in plan, elevation or sectional views, is only a different view of the same Symbol instance and will be counted as only one Object.


When bills of material, labour, and overhead have been computed and construction is about to begin, the project documents, including the complete project list of Objects and Modules for each project, are handed over to construction management. At this point data is transferred, via a script, from a CADD application to a book-keeping application that changes Objects into book-keeping Line Items and Keycodes into line item identification (ID) numbers for data recording, archiving, book-keeping, payroll and purchasing purposes. Items will follow different paths through recording, bookkeeping, and accounting processes according to their functions to provide the following information:

  • The prefix (first two digits) will tell when the work/function of each Line Item will be or was carried out.
  • The Uni-Format (The next three digits) will tell where in the building each Line Item will be or is located.
  • The Master Format (the next 5 digits) will denote, for each Line Item the material or product and the trade or team that will or has carried out the work.
  • The suffix (the last three digits) describes each Line Item that will be or is installed in the work.


The key to economical and expeditious building construction is best defined as a process of assembling rather than constructing buildings. Assembling buildings implies a neat and accurate process of precisely and easily locking together prefabricated components. This process can be applied to all parts of a modular inter-locked building, if carried out in an organized and systematic manner so that each worker knows exactly what is required of him at a specified stage, place and time in the assembly process. The automobile industry assembly line utilizes this concept as a linear progression along a moving path. Buildings are sufficiently similar to automobiles, with respect to the multiplicity of materials, the complimentary nature of tasks and the progressive method of construction, to raise the possibility of adapting the automobile assembly line method to assemble buildings. Other than mobile homes and house trailers, however, buildings are immobile and cannot be moved along an assembly line. To compensate for this limitation, construction workers become the mobile element in the assembly line, moving horizontally to assemble immobile rows of houses or in incremental phases for larger single storey structures or by moving vertically to assemble, floor-by-floor, multi-storey structures.

An assembly line requires off-line or out-sourced sub-assemblies for insertion, at appropriate points, into the assembly line. The sub-assembly and out-sourcing method may be applied, with very few modifications to assembling a building. In the LockBUILD system, off-line sub-assemblies are fabricated in a temporary on-site factory to ensure that they reach the assembly line with minimal handling and at just the right time.


The “art” of building lags behind the science of building materials. Traditional building materials have acquired capabilities that were previously unknown and the emerging potential of nano sciences in the creation of entirely novel building materials require a corresponding advance in methods and techniques to appropriately utilize these emerging building products and materials. More precise and regularized standards, couched in a clinically austere, functional, and clean working environment, should prevail and architects, engineers, builders and their crews must understand that they are ‘assembling’ and not ‘erecting’ or ‘building’ structures.