Bt5.pdf

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

Table of Contents Non-Conventional Methods of Construction ................................................................................................... 1 Drivers for building with modern methods of construction......................................................................... 1 Methods ........................................................................................................................................................... 2 1.

Volumetric construction ....................................................................................................................... 2

2.

Panellised construction systems .......................................................................................................... 3

3.

Hybrid Construction ............................................................................................................................. 5

4.

Sub-assemblies and components ......................................................................................................... 5

5.

Tunnel Form ......................................................................................................................................... 7

6.

Flat Slab ................................................................................................................................................ 8

7.

Thin Joint Masonry ............................................................................................................................. 10

8.

Lift Slab ............................................................................................................................................... 11

9.

Piled raft foundation .......................................................................................................................... 13

10.

Twin wall Construction .................................................................................................................. 14

References: ..................................................................................................................................................... 15

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

Non-Conventional Methods of Construction Since the Second World War, and the desperate need for new housing to be delivered quickly, modern methods of construction (MMC, or 'smart construction') has been promoted as a way of working more effectively to achieve more without using more. It centres on the use of offsite construction techniques that can benefit from factory conditions and mass production techniques. Modern methods of construction are about better products and processes. They aim to improve business efficiency, quality, customer satisfaction, environmental performance, sustainability and the predictability of delivery timescales. Modern methods of construction are, therefore, more broadly based than a particular focus on product. They engage people to seek improvement, through better processes, in the delivery and performance of construction.

Drivers for building with modern methods of construction  Shortage in housing supply High demand for housing is pushing up prices, making it more difficult for key workers and those on low incomes to find suitable accommodation. The development of affordable private sector dwellings is outside the control of Government so the focus has been on stimulating the development of MMC capacity as a means of increasing the rate of housing supply.  Concerns about housing quality There is a perception that build quality is declining, but that is probably due more to high profile media coverage of a few examples of poor practice and increasing customer expectations, than to an overall decline. Conventional construction can, and in most cases does, provide good quality housing but there is a general feeling that quality will need to improve if only to meet the higher performance standards needed to comply with the revised Building Regulations.  Revisions to Building Regulations When the Building Regulations were introduced, they were concerned only with the health and safety of people in and around buildings. More recently the Regulations have been broadened to cover the performance of buildings, particularly their thermal and acoustic performance.

Page | 1

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

 Environmental performance Increasing emphasis is being placed on the environmental performance of buildings, not only in use but also during construction, and the environmental credentials of the materials being used. There are other environmental benefits particularly for manufactured dwellings because much of the work is conducted in a factory; therefore the impact on the local community in terms of noise, dust and traffic movements associated with conventional construction sites is reduced.

Methods 1. Volumetric construction Three-dimensional units produced in a factory, fully fitted out before being transported to site and stacked onto prepared foundations. It is also referred to as modular construction. These units can be made from most materials including light gauge steel frame, timber frame, concrete and composites. The units are sometimes used alongside panels (readymade walls, floors, and roofs) in hybrid construction. Volumetric construction is most efficient when used for large numbers of identical units, as may be found in flats. A house is typically made up of four units plus roof (which can be either pre-fabricated or conventional). Benefits:        

Short construction time Reduced need for skilled workforce on site Less waste High quality control Reliable delivery timescale Price certainly Sustainable – can be relocated or recycled Light weight

The casting of modules uses the benefits of factory conditions to create serviceintensive units where a high degree of repetition and a need for rapid assembly on-site make its use highly desirable.

Page | 2

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

Room-sized modules are prefabricated and completed with internal finishes, fixtures and fittings, before being transported and installed on site.

2. Panellised construction systems Flat panel units built in a factory and transported to site for assembly into a threedimensional structure or to fit within an existing structure. Systems can include wall, floor and roof panels to create the complete structural shell. Factory-made structural floor and roof panels are known as “cassettes”. Different types of panel Open panels - panels delivered to site where insulation, windows, services and linings are fitted. All structural components are visible. Panels can be structural (transmitting load to the foundations) or non-structural (used as non-loadbearing separating walls and partitions) Open steel frame panels

Page | 3

Raz, Jim Bryan E. 201510324

Building Technology 5

Closed panels - panels based on a structural framing system (such as the type used for open panel systems), which can have factory fitted windows, doors, services, internal wall finishes and external cladding. The internal structural components can only be seen around the perimeter of the panel.

Ar. Lauro F. Ador

Closed timber frame panels being placed

Concrete panels - structural wall panels, which can include cladding (often bricks or brick slips), insulation materials, windows and doors. Composite panels - panels made from a combination of different materials that act together to provide structural support. Structural insulated panels are a specific form of composite panel. Structural insulated panels (SIPS) Sandwich construction comprising two layers of sheet material bonded to a foam insulation core. They do not rely on internal studs for their structural performance. Used primarily as wall and roof panels. Infill panels - non-loadbearing panels inserted within a structural frame. Any type of panel can be used although framed panels are more common. Masonry can also be used.

Page | 4

Concrete panels

Structural Insulated Panels

Light gauge steel infill panels

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

Curtain walling - vertical building enclosure system that supports no loads other than its own weight and the environmental loads that act upon it.

3. Hybrid Construction Volumetric units integrated with panellised systems. Hybrid construction is also referred to as semi-volumetric construction. Highly serviced areas such as kitchens or bathrooms can be constructed as volumetric units, with the rest of the dwelling constructed with panels.

4. Sub-assemblies and components Larger components that can be incorporated into either conventionally built or MMC dwellings. These items are not full housing ‘systems’ and are usually factory made or, occasionally, site-assembled. Sub-assemblies and components  Pre-fabricated foundations - a series of pre-fabricated ground beams and other components assembled to form foundations quickly and accurately.  Floor cassettes - pre-fabricated panels specifically designed for floor construction. Fewer labour hours on-site are needed per square metre of floor, and reduced work at height has potential health and safety benefits.  Roof cassettes - pre-fabricated panels designed specifically for pitched roofs. The panels are very stiff and are designed to leave the loft free of struts and props, allowing easy production of ‘room in the roof’ construction. Using roof cassettes

Page | 5

Pre-fabricated foundations

Floor cassettes

Raz, Jim Bryan E. 201510324

Building Technology 5

allows the building to become watertight more quickly than with conventional trussed rafter or cut roof constructions.  Pre-assembled roof structure - roofs assembled at ground level before constructing the shell of a dwelling. The roof can be craned into place as soon as the rest of the superstructure is in place, creating a weather tight structure more quickly than assembling the roof in site. There are also health and safety benefits resulting from the workforce not undertaking all the work at height.  Pre-fabricated dormers - factory made dormers can speed up the process of making the roof watertight.  Pre-fabricated plumbing - pipework and fittings pre-assembled for use in volumetric units to facilitate the rapid throughput of units in the factory.

Ar. Lauro F. Ador

Roof Cassettes

Pre-assembled roof structure

Pre-fabricated dormers

Pre-fabricated plumbing

Page | 6

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

5. Tunnel Form Tunnel form is a formwork system that allows the contractor to cast walls and slabs in one operation in a daily cycle. It combines the speed, quality and accuracy of factory/offsite production with the flexibility and economy of in-situ construction. The result is a cellular reinforced structure, the surfaces of which are sufficiently high quality to require only minimal finishing for direct decoration, while the end walls and facades are easily completed with thermally insulated units that can be clad as required. The system creates an efficient load-bearing structure for use in a wide variety of applications. It is particularly effective in projects suited to repetitive cellular construction such as residential blocks, hotels, student accommodation, barracks and prisons. Benefits:  Building - The formwork is specially adapted for each project. The repetitive nature of the system and the use of prefabricated forms and reinforcing mats/cages simplifies the whole construction process, producing a smooth and fast operation. The techniques used are already familiar to the industry, but with tunnel form construction there is less reliance on skilled labour.  Quality - Quality is enhanced despite the speed of construction. The precise, even steel face of the formwork creates a smooth, high quality finish capable of receiving direct decoration with the minimum of preparation (a skim coat may be required). This reduces the requirement for following trades, thus providing additional cost savings and speeding the entire process.  Design - The large bays constructed using tunnel form provide exceptional flexibility in the design and layout of the building and allow a high degree of freedom in the final appearance.  Safety - Tunnel form has integral working platforms and edge protection systems. In addition, the repetitive, predictable nature of the tasks involved encourages familiarity with operations, and, once training is complete, productivity improves as construction progresses. The minimal requirement for tools and equipment when moving the tunnel form further reduces the risk of accidents on site.  Sustainability- The insitu casting of units on site and the local availability of readymixed concrete supplies reduce transportation impacts. Just-in-time deliveries and near zero wastage produce an overall tidier site with associated cost savings and safety benefits. Page | 7

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

6. Flat Slab Flat slab is a reinforced concrete slab supported directly by concrete columns without the use of beams. Flat slab is defined as one sided or two-sided support system with sheer load of the slab being concentrated on the supporting columns and a square slab called ‘drop panels’. Drop panels play a significant role here as they augment the overall capacity and sturdiness of the flooring system beneath the vertical loads thereby boosting cost effectiveness of the construction. Usually the height of drop panels is about two times the height of slab. Flat Slabs are considered suitable for most of the construction and for asymmetrical column layouts like floors with curved shapes and ramps etc. The advantages of applying flat slabs are many like depth solution, flat soffit and flexibility in design layout. Benefits: 



Page | 8

Flexibility in room layout - Flat slabs allows Architect to introduce partition walls anywhere required, this allows owner to change the size of room layout. Use of flat slab allows choice of omitting false ceiling and finish soffit of slab with skim coating. Saving in building height - Lower storey height will reduce building weight due to lower partitions and cladding to façade.

Raz, Jim Bryan E. 201510324

 



Building Technology 5

Shorter construction time - Use of flat slabs requires less time for construction by the use of big table formwork. Use of prefabricated welded mesh - Use of prefabricated welded mesh minimizes the installation time of flat slabs. These mesh are available in standard size and provides better quality control in construction of flat slab. Buildable score - This allows standardized structural members and prefabricated sections to be integrated into the design for ease of construction. This process makes the structure more buildable, reduce the number of site workers and increase the productivity at site, thus providing more tendency to achieve a higher Buildable score.

Disadvantages:     

Page | 9

Ar. Lauro F. Ador

Span length is medium Not suitable for supporting brittle (masonry) partitions Use of drop panels may interfere with larger mechanical ducting Critical middle strip deflection Higher slab thickness

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

7. Thin Joint Masonry Thin joint masonry is a fast, clean, accurate system for construction using autoclaved aerated concrete blocks of close dimensional tolerance with 2mm-3mm mortar joints. Thin layer mortar is a pre-mixed cement-based product that only requires the addition of water to make an easily-applied mortar. It differs from general use mortar in that it sets more rapidly, thus giving early stability to the construction. It provides an alternative to traditional sand/cement mortar and allows the depth of the mortar to be reduced from at least 10mm to 3mm or less. Benefits:  Faster build speed - Thin layer mortar is applied to autoclaved aerated concrete blocks by the use of a serrated scoop, which allows mortar to be applied quickly and accurately to the bed joints and perpends. The benefits are fully realised on long runs of walling.  Increased productivity - The system ensures high levels of productivity. Autoclaved aerated block walls built with thin layer mortar will typically be stable after 60 minutes. This will allow whole walls to be built in less time and enables earlier installation of other components, such as floors and roof timbers.  Improved thermal performance - The construction of thin joint block work minimises this effect by reducing the amount of mortar in any given area of wall by at least 70% compared with general use mortar construction.  Improved airtightness - Excellent airtightness can be achieved using thin joint technology, thereby improving the overall performance of the wall in terms of heat loss.  Reduced site wastage - A key benefit of autoclaved aerated concrete blocks is that they can be easily and accurately cut, sawn and worked on site. The precision cutting of blocks for use with thin layer mortar allows greater utilisation of the blocks, which can substantially reduce site wastage. Mortar wastage can also be minimised with the batch mixing of small quantities of thin layer mortar.  Improved construction quality - The combination of high tolerance blocks and thin layer mortar allows greater accuracy to be achieved in the internal face of a completed wall, which can provide a suitable substrate for the application of thin coat spray plaster. This has the added advantage of fast application and quick drying time, resulting in further productivity gains.

Page | 10

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

8. Lift Slab Lift slab construction (also called the Youtz-Slick Method) is a method of constructing concrete buildings by casting the floor or roof slab on top of the previous slab and then raising (jacking) the slab up with hydraulic jacks. This method of construction allows for a large portion of the work to be completed at ground level, negating the need to form floor work in place. The ability to create monolithic concrete slabs makes the lift slab construction technique useful in quickly creating structures with repetitive form work, like parking ramps.

Page | 11

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

Process:  Concrete - To begin, a concrete slab is first poured on the ground level. Lifting collars are set around each of the columns and cast into place as the slab is poured around them. The lifting collars will later be used to support the slab as it is raised and secured in place. Subsequent floors and the roof are then poured and formed on top of the initial ground slab. Bond breakers are used between each floor plate to allow the slabs to separate as they are raised. Along with reducing the formwork required to create the slabs, slabs can be easily protected from inclement weather since all of the slabs remain together during the curing process  Lifting - Once the slabs have been raised to their desired height the lifting collars are welded to the columns, along with shear blocks to support the slab from beneath. To assure the security of a structure during the raising of the slabs, the hydraulic jacks, attached to the top of the columns, use synchronized consoles to lift the slabs at an even rate. Conventional methods of mounting the jacks to the columns require that the jacks are removed before continuing to raise the slabs. More recent approaches utilize welded plates, separated from the columns, to support the jack.

Page | 12

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

9. Piled raft foundation Foundations provide support for structures, transferring their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement characteristics. Very broadly, foundations can be categorised as shallow foundations or deep foundations:  Shallow foundations are typically used where the loads imposed by a structure are low relative to the bearing capacity of the surface soils.  Deep foundations are necessary where the bearing capacity of the surface soils is not adequate to support the loads imposed by a structure and so those loads need to be transferred to deeper layers with higher bearing capacity. In their normal form, raft foundations (sometimes referred to as mat foundations) are shallow foundations formed by a reinforced concrete slab of uniform thickness (typically 150-300 mm) covering a wide area, often the entire footprint of a building. This 'raft' spreads the load imposed by a number of columns or walls over the area of foundation, and can be considered to ‘float’ on the ground as a raft floats on water. However, where a conventional raft foundation does not provide adequate support, it can be enhanced by the addition of piles, creating what is known as a piled raft foundation.

Page | 13

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

10. Twin wall Construction Twinwall construction is a walling system that combines the speed of erection and quality of precast concrete with the structural integrity of in-situ concrete to provide a hybrid solution. The prefabricated panels comprise two slabs separated and connected by cast-in lattice girders. The units are placed, temporarily propped, and then joined by reinforcing and concreting the cavity on site. Twinwall is usually employed in association with precast flooring systems. The panels are manufactured to exacting tolerances, have a high quality finish, and can incorporate cast-in cable ducts, electrical boxes and service ports. Installation rates are of up to 100m2 per hour. Twinwall has excellent inherent fire resistance and acoustic performance. Twin wall construction is a hybrid of precast and in-situ concrete walls and floors. Each wall unit comprises of two plates of precast concrete with a cavity between, linked by a lattice of steel reinforcement and placed on site; effectively as permanent concrete formwork. Once units and water bars are in place the cavity is filled with in-situ concrete to complete the structural wall. Twin wall systems offer all the benefits of precast concrete but with the added benefit of continuous cast in situ concrete across the whole wall and, potentially, floor.

Page | 14

Raz, Jim Bryan E. 201510324

Building Technology 5

Ar. Lauro F. Ador

References: 

http://trentglobal.com/docs/A%20Guide%20to%20Modern%20Methods%20of%20Construction. pdf



https://mndsingapore.wordpress.com/2014/08/14/game-changing-technology-to-upproductivity/



https://www.slideshare.net/philwdm/modular-volumetric-construction



https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=2ahUKEwjj4sv2 vuTcAhXEw7wKHYDaC4QQjxx6BAgBEAI&url=https%3A%2F%2Fwww.the-self-buildguide.co.uk%2Fsteel-framehouses.html&psig=AOvVaw3flC3fGRWvN4T_fMolExyZ&ust=1534059416089714`



https://www.homebuilding.co.uk/how-to-choose-a-timber-frame-system/



https://specifier.com.au/timbertruss-floors-customers-with-cassettes/



https://www.concretecentre.com/Building-Elements/Walls/Tunnel-form.aspx



https://theconstructor.org/structural-engg/flat-slab-types-design-advantages/13919/



https://taxonomy.openquake.org/terms/flat-slab-plate-or-waffle-slab--lfls



https://www.concretecentre.com/Building-Elements/Walls/Thin-joint-blockwork.aspx



https://en.wikipedia.org/wiki/Lift_slab_construction



https://www.concretecentre.com/Building-Elements/Walls/Twinwall.aspx



http://www.keeganprecast.com/technical-data?prod=twin-wall

Page | 15