Modular construction

BUILDING CONSTRUCTIONSubmitted by_TABISH NEHA

Mobile homes are constructed entirely in a factory and then moved to a site location where they are placed on concrete slabs. Wheels are removed, and though they remain moveable, this rarely occurs. Panelized homes consist of factory-built walls (windows and doors included) that are shipped as one-dimensional units to be assembled on-site. Pre-cut houses provide the elements in pre-sized and pre-shaped puzzle-type pieces to be put together by a builder using traditional means. Modular housing is factory-assembled in full-dimensional units. They are built to state and local building codes and must be installed on a foundation.

Why Modular construction?It was chosen for a variety of reasons. With industrial technology, quality control, product inspection every step of the way, and the building standards imposed by law, it seemed an unquestionably sound choice. Costs are controlled, as all materials are purchased in volume and technicians and craftsmen work as a team. Time, too, is economized, as construction continues in spite of weather, and the assembly line can run beyond the days and seasons for outdoor work. Today's modular houses can range in size from 1,000 to 6,000 square feet and can be designed to accommodate everything from the simple needs and/or budgets of senior citizens or entry-level buyers, to the high-end designer style incorporated into this one. With average costs ranging from 10 to 25 percent less than stick-built, modular homes offer an affordable choice. In the past this affordability provided housing (and commercial buildings) on a limited

From PreFabHome by Michael Buchanan 2004

Need of Modular Construction:Construction workers typically are exposed to high levels of noise, dust and airborne particles, adverse weather conditions, and other factors that can cause fatigue and injuries and thereby reduce efficiency and productivity. New types of equipment can make an activity physically easier to perform, easier to control, more precise, and safer for construction workers. Similarly, changes in materials can reduce the weight of construction components, which in turn can make them easier to handle, move, and install. Manufacturing building components off–site provides for more controlled conditions and allows for improved quality and precision in the fabrication of the component.

Prefabrication, preassembly, modularization, and off-site fabrication involve the assembly or fabrication of building systems and/or components at off–site locations and plants. Once completed, the systems or components are shipped to a construction job site for installation at the appropriate time. One study that examined the relationship between changes in material technology and construction productivity based on 100 construction–related tasks found the following:• Labor productivity for the same activity increased by 30 percent where lighter materials were used; and• Labor productivity also improved when construction activities were performed using materials that were easier to install or were pre–fabricated (Goodrum et al., 2009).

What is modular construction? It is a building methodology whereby elements of a project are mass produced and assembled to make larger finished products. An entire project can be based on modularity—think beyond just the modular patient room. Like sustainable projects, make modular a core value of the project, not just an element that can be dropped from the program. Identify as many project components as possible including programmatic elements of patient rooms, Operating Rooms, Emergency Departments, exam and treatment rooms, nurses’ stations, bathrooms, pharmacy and laboratories, and building elements such as structure, exterior envelope, and MEP systems (headwalls, bathroom wet walls, and overhead piping and ductwork). With the increased integration of BIM in the development of projects, incorporating modular building components becomes easier and more desirable.

Modular construction

BUILDING CONSTRUCTIONSubmitted by_TABISH NEHA

How Are Modular Structures More Beneficial?Modular construction techniques have been shown to be inherently advantageous in 7 major areas

Less Materials Waste — Pre-fabrication makes it possible to optimize construction materials purchases and usage while minimizing on-site waste and offering a higher quality product to the buyer. Bulk materials are delivered to the manufacturing facility where they are stored in a protected environment, safe from theft and exposure to the environmental conditions of a job site.

Less Material Exposure to Inclement Weather — Many of the indoor air quality issues identifi ed in new construction result from high moisture levels on the framing materials. Because the modular structure is substantially completed in a factory-controlled setting using dry materials, the potential for high levels of moisture being trapped in the new construction is eliminated.

Less Site Disturbance — The modular structure is constructed off-site simultaneously with foundation and other site work, thereby reducing the time and impact on the surrounding site environment, as well as reducing the number of vehicles and equipment needed at the site.

Safer Construction — Modular construction is a safer alternative. Conventional construction workers regularly work in less-than-ideal conditions, dealing with temperature extremes, rain, wind or any combination of natural conditions. This by its very nature is a much more challenging environment for working safely.

Additionally, the potential for injury— including falls, the most common work site risk—is much higher. In a factory-controlled setting, each worker is typically assigned to a work station supplied with all the appropriate equipment needed to provide the safest work environment possible. Off-site construction also eliminates the hazards associated with materials, equipment and incomplete construction processes typical of construction sites that can attract curious and unwelcome “visitors” (e.g. students on a school expansion project).

Flexibility — When the needs change, modular buildings can be disassembled and the modules relocated or refurbished for their next use reducing the demand for raw materials and minimizing the amount of energy expended to create a building to meet the new need. In essence, the entire building can be recycled in some cases.

Adaptability — Modular buildings are frequently designed to quickly add or remove one or more “modules”, thereby minimizing disruptions to adjacent buildings and surroundings.

Built to Code With Shorter Build Times — The bottom line is that with modular construction you can get a facility built to the same local codes with construction quality as good as or better than a comparable site built building in much less time. Additionally. the abbreviated construction schedule allows you to get a return on your investment sooner while minimizing the exposure to the risks commonly associated with protracted construction schedules.

DisadvantagesWhilst there are many advantages to all forms of modular buildings, there can be limitations also.Volumetric: Transporting the completed modular building sections take up a lot of space. This is balanced with the speed of construction once arrived on site.Flexibility: Due to transport and sometimes manufacturing restrictions, module size can be limited, affecting room sizes. Panelised forms and flat pack versions can provide easier shipment, and most manufacturers have flexibility in their processes to cope with the majority of size requirements.Aesthetics: prefabricated identical units that are later joined together may be viewed as less aesthetically pleasing and less desirable as a residence than than a traditional home which is individually built on site.

Modular coordination

BUILDING CONSTRUCTIONSubmitted by_TABISH NEHA

30-storey hotel built in 15 days in China

Modular Coordination (MC) It is a concept for coordinating dimension and space for which buildings and components are dimensionalised and positioned in basic units or modules. MC has been introduced in Malaysia since 1986, but has not been widely implemented in the building industry. The main factors limiting the uses of MC in building industries is lack of knowledge on MC concept and it requires precision dimensioning and proper planning.

The characteristis of MC are:- The basic module is small in terms of odd size in order to provide design flexibility, yet large enough to promote simplification in the components' variation in sizes.- Industry friendly features that not only cater for manufacturing but also the transportation and assembly requirements.- Ergonomically designed to promote efficiency- Internationally accepted to support international market

MC Concept

MC may be applied to the design, manufacture and assembly of buildings, its components and installations. It also affects the work positioning and dimensioning during construction. At the work level, MC allows for relative independence in decision making with the common dimensional language.

The concept of MC is based on:- The used of modules (basic modules and multi-modules)- A reference system to define coordinating spaces and zones for building elements and for the components which form them- Rules for locating building elements within the reference system- Rules for sizing building components in order to determine their work size- Rules for defining preferred sizes for building components and coordinating dimensions for buildingThe principal objective of implementing MC is to improve productivity through the reduction of wastages in the production, installation process, to improve quality in the construction industry and to encourage an open system. With Open System approach, building components could combine in a variety of individual building projects while ensuring the architect freedom in their designs.

MC is an important factor in application of Industrialised Building System by way of standardization of components ad dimensions such as reduce time of production and installation of components, achieving repeatability and able to construct building at lower cost.

Benefits of Implementing Modular CoordinationThe benefits of practicing modular coordination is to provide a practical approach towards the following:•Facilitates cooperation between building designers, manufacturers, distributors, contractors and authorities.•In the design work, enables buildings to be so dimensioned that they can be erected with standard components without undue restriction on freedom of design.•Permits a flexible type of standardization, which encourages the use of a limited number of standardized building components for the construction of different types of buildings.•Optimizes the number of standard sizes of building components. Encourages as far as possible the interchangeability of components, in whatever materials, forms or methods of manufacture.•Simplifies site operations by rationalizing setting out, positioning and assembly of building components.•Ensures dimensional coordination between installation (equipment, storage units, other fitted furniture, etc.) as well as with the rest of the building.

Terms:Modular (Electrical) WiringA preassembled electrical cabling system, using pre-terminated electrical cables usually made up into looms or wiring harnesses to provide the electrical distribution system for all mains small power, lighting and appliances.Multi-Purpose Riser•Multiple service vertical distribution module, constructed from primed or galvanized mild steel and incorporating appropriate building services which may or may not be insulated.

These modules can be connected offsite, but are often transported in 7.5m lengths to avoid transportation problems.•The majority of the electrical risers are manufactured using a mesh or ladder system to allow easy distribution at floor levels in various directions.•While the base structure may offer a level of standardization the dimensions and carrying capacity will vary from between projects.

Beam and Block Floor•Extruded or wet cast prestressed beams between 150 and 225mm deep, spaced to suit the appliedloading and spans, together with blocks of various types.•These may be purpose-made blocks with rebates to suit the shape of the beams (‘tray blocks’).•Also commonly used are specially shaped extruded or expanded polystyrene blocks which provide a high degree of insulation for ground floors.Component•A term used loosely for items that are manufactured offsite and then assembled together with other components.•If this is completed offsite then the product is defined as a whole.

Careful design of componentsand their interfaces is crucial foreffective manufacture andassembly.

Panel Building System•Comprising walls, floors and roofs in the form of flat pre-engineered panels that are erected onsite to form the box-like elements of the structure that then require various levels of finishing.•This term applies to all different material types.Pre-cast Flat Panel System•Floor and wall units are produced offsite in a factory and erected onsite, ideal for all repetitive cellular projects.• Panels can include services, windows, doors and finishes.• Building envelope panels with factory fitted insulation and decorative cladding can also be used as load-bearing elements.Plant Room Module (preassembled)Packaged or skid-mounted preassembled plant rooms prefinished in the factory, ready for direct connection to mains services Onsite (AHU’s, fans, chillers, boilers, pumps together with elements of the building envelope.MODULAR COORDINATIONA module can be defined as a basic dimension which could for example form the basis of a planning grid in terms of multiples and submultiples of the standard module.TYPICAL MODULAR COORDINATED PLANNING GRID:Let M = the standard module

Structural Grid –used to locate structural components such as beams and columns.Planning Grid basedon any convenient modular multiple for regulating space requirements such as rooms.Controlling Grid –based on any convenient modular multiple for location of internal walls, partitions dc.Basic Module Grid –•used for detail location of components and fittings.•All the above grids, being based on a basic module, are contained one within the other and are therefore interrelated.•These grids can be used in both the horizontal and vertical planes thus forming a three dimensional grid system.• If a first preference numerical value is given to M dimensional coordination is established.

Dimensional Grids - the modular grid network defines the space into whichdimensionally coordinated components must fit. An important factor is that the component must always be undersized to allow for the joint which is sized by the obtainable degree of tolerance and site assembly :

Dimensions in modular coordination:

•In the construction industry, it was felt that typical dimensions must be easy to use in mental arithmetic.•Therefore, rather than using elements of a geometric series, a different system of preferred dimensions has evolved in this area, known as "modular coordination".•Major dimensions (e.g., grid lines on plans, distances between wall centers or surfaces, widths of shelves and kitchen components) are multiples of 100 mm, i.e. one decimetre.• This size is called the "basic module" and represented by the letter M.•For larger dimensions, preference is given to multiples of the modules 12 M (= 1.2 m), 15 M (= 1.5 m), 30 M (= 3 m), and 60 M (= 6 m). For smaller dimensions, the submodular increments 50 mm or 25 mm are used.•Dimensions chosen this way can easily be divided by a large number of factors without ending up with millimetre fractions.

Modular coordination

BUILDING CONSTRUCTIONSubmitted by_TABISH NEHA