Field of the invention

[0001] The present invention relates to a method for construction of a building. In particular, the invention relates to a method of pre-fabricated pre-finished volumetric construction of a building.

Background of the invention

[0002] Traditional construction methods for infrastructures, which involve building primary structural elements entirely or largely on-site, typically follow a linear specific sequence where an appropriate step needs to be completed before a next step can begin. As such, building progress and qualities of infrastructures built using traditional construction methods are often susceptible to external factors such as weather conditions, an available manpower, qualities of workers etc.

[0003] In recent years, an alternative building method, modular construction, is gaining much popularity. Modular construction is a process where structural elements (or modules) are prefabricated off-site prior to transportation of the completed or mostly completed modules to a site of construction for assembly. A form of modular construction is prefabricated prefinished volumetric construction (PPVC), where the prefabricated modules are also fitted with internal finishes, fittings and fixtures in a factory off-site before the completed modules are transported on-site for final assembly.

[0004] One type of PPVC involves a shear wall structural system comprising braced panels (also known as shear walls) which are used to counter the effects of lateral load acting on a structure. In particular, a shear wall provides stiff resistances to vertical and horizontal forces acting in its plane and is capable of transferring loads vertically to a building's foundation. However, this results in less flexibility for an internal design of the building since these shear walls, which act as supporting structures, cannot be demolished or removed. Moreover, a type of modular construction involves only five-walled modules (e.g. a module without a roof). The five-walled modules used in such a modular construction reduce ease and safety of assembly on-site since workers are not provided with a platform for working on top of these five-walled modules during the final assembly on-site. In addition, such five-walled modules cannot be completely finished internally off-site (e.g. mechanical and electrical connections cannot be pre-installed since no ceiling is provided for each five-walled module), thereby resulting in more time required for assembly and finishing on-site. [0005] It is therefore an aim of the present invention to provide an improved method for construction that helps to ameliorate one or more of the above problems.

Summary of the invention

[0006] In accordance with a first aspect of the present invention, there is provided a method for constructing a p re-fabricated pre-finished volumetric construction (PPVC) module for a building. The method comprising:

casting of concrete to form a body of the PPVC module, wherein the body of the PPVC module comprises one or more load-bearing columns and beams, and six walls including a roof that covers a top of the PPVC module; and

substantially finishing an interior of the PPVC module before the PPVC module is transported to a site for assembly into a building.

[0007] Embodiments of the invention therefore provide a method for constructing a prefabricated pre-finished volumetric construction (PPVC) module for a building. In particular, the method comprises: (i) casting of concrete to form a body of the PPVC module, where the body of the PPVC module comprises one or more load-bearing columns and six walls including a roof that covers a top of the PPVC module; and (ii) substantially finishing an interior of the PPVC module before the PPVC module is transported to a site for assembly into a building. The provision of a roof (i.e. a sixth wall) in the PPVC module advantageously provides protection for workers and finishes from weather elements, while allowing installation of safety barricades using cast-in provisions on the roof of the PPVC module to improve safety for workers during on-site assembly/installation of the PPVC modules. The provision of a roof also improves efficiency for construction as it provides a platform for light human traffic during PPVC module assembly and it permits simple stacking of PPVC modules for easy installation. Moreover, the six-sided PPVC module minimises structural connection inspection and building maintenance since each PPVC module is self-contained, and improves containment of fire in an event of a fire breakout. The overall building cost of construction may be reduced due to savings gained as a results of more efficient construction (e.g. decreasing manpower and logistics costs) and improved safety on-site (e.g. decreasing housekeeping costs).

[0008] In addition, the load-bearing columns and beams system employed in each PPVC module advantageously enhances the structural performance of a building compared to a conventional load-bearing shear wall system since it improves lateral load transfer (e.g. wind or earthquake etc.).

[0009] In accordance with a second aspect of the invention, there is provided a method of assembling a plurality of PPVC modules, the method comprising: positioning a second PPVC module adjacent to a first PPVC module; providing a bar in a cavity of each of the first and second PPVC modules; and providing a connecting plate between the bars of the first and second PPVC modules, the connecting plate being operationally connected to the bars of the first and second PPVC modules.

[0010] The method may comprise providing at least one spacer in a region of a top end of each cavity adjacent to each of the bars of the first and second PPVC modules, wherein the at least one spacer is positioned in an area of recess formed by a recessed edge of the top of each of the first and second PPVC modules and wherein the at least one spacer is positioned beneath the connecting plate.

[0011] The method may comprise providing at least one coupler at a top end of each of the bars.

[0012] The method may comprise providing a mortar bedding extending between the bars of the first and second PPVC modules atop the connecting plate, the mortar bedding being operationally connected to the at least one coupler of each of the first and second PPVC modules.

[0013] The method may comprise providing a grout, wherein the grout fills each of the cavities of the first and second PPVC modules and covers the connecting plate.

[0014] The method may comprise:

aligning another two adjacent PPVC modules above the first and second PPVC modules, wherein each cavity of the another two adjacent PPVC modules is positioned over a respective cavity of the first and second PPVC modules;

providing another bar into each cavity of the another two adjacent PPVC modules; and

fastening the another bars onto each respective at least one coupler.

[0015] The method may comprise providing another grout, the another grout fills each of the cavities of the another two adjacent PPVC modules and covers each of the at least one coupler of the first and second PPVC modules.

[0016] The method may comprise providing a rod in a gap between the first and second PPVC modules, wherein the rod is placed in a direction parallel to a length of the top of the first and second PPVC modules.

[0017] The method may comprise applying a sealant between the gap wherein the sealant covers the rod and a top of the gap. [0018] In accordance with a third aspect of the present invention, there is provided a PPVC module for pre-fabricated pre-finished volumetric construction (PPVC) of a building, the module comprising:

a body, wherein the body comprises one or more load-bearing columns and beams, and six walls including a roof at a top of the PPVC module.

[0019] The PPVC module may comprise:

a bar provided within a cavity of the body; and

a recessed edge at a top end of the cavity.

[0020] The PPVC module may comprise a plurality of cast-in provisions at the roof for further attachment of further elements.

[0021] The PPVC module may comprise one or more safety barricades wherein the one or more safety barricades are secured using the plurality of cast-in provisions at the roof.

[0022] In accordance with a third aspect of the present invention, there is provided an assembly comprising two or more of the preceding PPVC modules.

[0023] The assembly where the preceding PPVC module is fixedly connected to another adjacent PPVC module, each of the module may comprise:

at least one spacer placed in a region of the top end of the cavity besides the bar, the at least one spacer being positioned in an area of recess formed by a recessed edge of each of the PPVC modules; and

a coupler at a top of the bar.

[0024] The assembly may comprise a connecting plate provided between the bars of each of the PPVC modules, the connecting plate being operationally connected to the bars of the PPVC modules.

[0025] The assembly may comprise a grout filling each of the cavities of the PPVC modules and the area of recess, and covering the at least one spacer of each PPVC module and the connecting plate.

[0026] The assembly may comprise a mortar bedding extending between the bars of the PPVC modules atop the connecting plate, the mortar bedding being operationally connected to the at least one coupler of each of the PPVC modules.

[0027] The at least one spacer may be held under compression by the connecting plate.

[0028] The present invention aims to provide an improved method for construction that helps to improve productivity while decreasing construction time. Brief description of the drawings

[0029] Non-limiting embodiments of the invention will now be described for the sake of example only, with reference to the following drawings in which:

Fig. 1 shows an illustration of a building constructed using pre-fabricated pre-finished construction (PPVC) modules in accordance with an embodiment of the invention;

Fig. 2 shows steps of a method for PPVC of a building in accordance with an embodiment of the invention;

Fig. 3 shows an illustration of a PPVC module with six walls in accordance with an embodiment of the invention;

Fig. 4 shows an illustration of load-transfer in a PPVC column and beam system in accordance with an embodiment of the invention;

Fig. 5, comprising Figs. 5A and 5B, shows illustrations of applying protection to a PPVC module in accordance with an embodiment of the invention;

Fig. 6 shows an illustration of different types of facade available for a PPVC module in accordance with embodiments of the invention;

Fig. 7 shows an illustration of lifting of a PPVC module in accordance with an embodiment of the invention;

Fig. 8 shows steps of a method for providing safety barricades on a PPVC module in accordance with an embodiment of the invention;

Fig. 9 shows an illustration of a PPVC module fitted with safety barricades using cast-in provisions in accordance with an embodiment of the invention;

Fig. 10 shows an illustration of a plurality of PPVC modules fitted with safety barricades using cast-in provisions in accordance with an embodiment of the invention;

Fig. 1 1 , comprising Figs. 1 1A and 11 B, shows illustrations of lateral connections between adjacent PPVC modules in accordance with an embodiment of the invention;

Fig. 12 shows steps of a method for connecting two PPVC modules laterally in accordance with an embodiment of the invention;

Fig. 13 shows an illustration of a rod and a sealant provided in a gap between two adjacent PPVC modules in accordance with an embodiment of the invention; Fig. 14 shows a perspective view of a plurality of PPVC modules where a rod and a sealant are applied along a perimeter of a common area between two adjacent PPVC modules in accordance with an embodiment of the invention;

Fig. 15 shows an illustration of a gap between two adjacent PPVC modules with a rod and a sealant in accordance with an embodiment of the invention;

Fig. 16 shows an illustration of two bars provided in each one of two cavities of adjacent PPVC modules in accordance with an embodiment of the invention;

Fig. 17 shows an illustration of two spacers and a connecting plate between the bars of the PPVC modules in accordance with an embodiment of the invention;

Fig. 18 shows an illustration of a coupler on each bar in each cavity of the PPVC modules in accordance with an embodiment of the invention;

Fig. 19 shows an illustration of a grout filling each of the cavities and covering the connecting plate in accordance with an embodiment of the invention;

Fig. 20 shows an illustration of a mortar bedding extending between the bars in accordance with an embodiment of the invention;

Fig. 21 shows steps of a method for filling a gap between two adjacent PPVC modules using a rod and a sealant in accordance with an embodiment of the invention;

Fig. 22 shows steps of a method for connecting PPVC modules vertically in accordance with an embodiment of the invention;

Fig. 23 shows an illustration of another two adjacent PPVC modules aligned above the PPVC modules of Fig. 20 in accordance with an embodiment of the invention;

Fig. 24 shows an illustration of bars provided in cavities of the another two adjacent PPVC modules in accordance with an embodiment of the invention;

Fig. 25 shows an illustration of bars provided in cavities of four PPVC modules for connecting the four PPVC modules in accordance with an embodiment of the invention;

Fig. 26 shows an illustration of a grout filling each of the cavities of the another two adjacent PPVC modules in accordance with an embodiment of the invention;

Fig. 27 shows an illustration of a cross-sectional view of eight PPVC modules in accordance with an embodiment of the invention; Fig. 28 shows an illustration of connecting joints at an intersection of four PPVC modules in accordance with an embodiment of the invention;

Fig. 29 shows a cross-sectional view of two vertically-stacked PPVC modules in accordance with an embodiment of the invention;

Fig. 30 shows an enlarged view of a cross-section of two vertically-stacked PPVC modules in accordance with an embodiment of the invention;

Fig. 31 , comprising Figs. 31A, 31 B and 31C, shows illustrations of mechanical, electrical and plumbing (MEP) services and a false ceiling provided between adjacent PPVC modules in accordance with an embodiment of the invention;

Fig. 32 shows a plan view of a cross-section of four laterally connected PPVC modules in accordance with an embodiment of the invention;

Fig. 33 shows a plan view of a cross-section of three laterally connected PPVC modules in accordance with an embodiment of the invention;

Fig. 34 shows an illustration of dry and wet areas partitioned in a PPVC module in accordance with an embodiment of the invention; and

Fig. 35 shows an illustration of a roof deck constructed at a top of a plurality of PPVC modules in accordance with an embodiment of the invention.

Detailed description of the embodiment

[0030] The present invention aims to provide an improved method for construction that helps to improve productivity and safety while decreasing construction time. In particular, a PPVC module with six walls (i.e. a floor, four walls and a roof) is provided that advantageously offers protection for workers and finishes from weather elements and allows installation of safety barricades to improve safety for workers during on-site assembly/installation of PPVC modules. The provision of a roof improves efficiency for construction as it allows interiors to be finished to a greater degree off-site and provides a platform for light human traffic during PPVC module assembly while also permitting simple stacking of PPVC modules for easy installation. Moreover, a six-sided PPVC module minimises structural connection inspection and building maintenance since each PPVC module is self- contained. A concrete six-sided PPVC module also improves containment of fire in an event of a fire breakout. In addition, a load-bearing column and beam system employed in each PPVC module advantageously enhances the structural performance of a building compared to a conventional load-bearing shear wall system since it improves lateral load transfer (e.g. due to wind or earthquake etc.). [0031] Fig. 1 shows an illustration of a building 100 constructed using pre-fabricated pre- finished construction (PPVC) modules in accordance with an embodiment of the invention. The building as shown comprises a plurality of PPVC modules 1 10 with pre-finished interior and facade adjoined together to form the building 100. During assembly or installation of the PPVC modules on-site, a central structural core 102 may be erected several floors ahead prior to the installation of the PPVC modules 110. Tie brackets or connecting plates may be used to connect the PPVC modules 110 to the central structural core 102 for stability. The methods for assembling the PPVC modules 110 will be discussed in further detail in relation to Figs. 12 to 26.

[0032] Fig. 2 shows steps of a method 200 for PPVC of a building in accordance with an embodiment of the invention. Steps 204, 208 and 210 shown in dotted lines are optional steps.

[0033] In a step 202, a body of the PPVC module 1 10 is formed by casting concrete. The body of the PPVC module comprises at least one load-bearing column and/or at least one structural beam, and six walls including a roof that covers a top of the PPVC module. One or more of the six walls may comprise an opening for full-height windows or walls. One or more balcony and/or air-conditioning ledge may also be attached to the body of the PPVC module. The body of the PPVC module 1 10 may be fabricated in a concrete casting factory off-site. Pre-casting checks may be carried out, for example, to ensure that the dimensions of a mould for concrete casting are within specified tolerances. Any rebars or cast-in items in the body of the PPVC module may also be formed and casted into the concrete of the body in this step.

[0034] In a step 204, the concrete PPVC module may be received at another factory for internal fittings, if casting of the concrete and installation of fittings are not performed at the same place. Upon receipt, inspection of dimensions and conditions of a structure of the concrete PPVC module may be performed to ensure structural integrity. For example, the actual dimensions of the body of the PPVC module may be compared to design drawings to ensure that the PPVC module is fabricated to scale. The concrete may also be tested for its strength and moisture to ensure that the concrete meets the necessary requirements.

[0035] In a step 206, an interior of the PPVC module is fitted (i.e. finished). Fitting of the interior of the PPVC module involves a number of phases, namely - (i) installing internal/external partition wall boards; (ii) installing mechanical/electrical (M&E) pipes and wirings (e.g. electricity lines and sockets, water pipes, air-conditioning ducts, gas lines etc.); (iii) performing water-proofing works with at least two coatings; (iv) installing toilets, basins, bath-tubs/shower units and kitchen frames and applying water- proofing where necessary; (v) water-proofing and performing a ponding test to check for any water leakage; (vi) performing wall tiling works; (vii) installing ceiling frames, mechanical/electrical (M&E) lateral connections and painting an interior and an exterior of the PPVC module; (viii) performing floor tiling works; (ix) performing pressure tests for mechanical pipes and carrying out electrical tests; (x) installing mirrors; (xi) installing vanity cabinets and kitchen cabinets; (xii) installing shower screens (if necessary); and (xiii) installing basin sinks, air- conditioning units, heaters and/or water-mixers. Inspection and checks may be performed as each phase is completed. For example, after M&E pipes and wirings are installed, locations of these installations may be checked against that in the design drawings. Workmanships and qualities of the materials (e.g. tiling works, installation of mirrors, cabinets, air-conditioning units etc.) may also be inspected at each phase. The fitting process as described may be performed in a sheltered factory environment.

[0036] In a step 208, all the interior fittings performed in the step 206 will undergo a final inspection. Any defects found at this stage are rectified accordingly. The PPVC modules manufactured will meet all statutory requirements and there is a complete quality system in place to ensure proper execution of all processes during the course of PPVC module production.

[0037] In a step 210, protection is applied to all fitted materials as well as the interior and an exterior of the PPVC module. For example, suitable protective film or cling wraps may be used to protect architectural finishes from deteriorating over time or during transport and assembly.

[0038] In a step 212, the PPVC module is delivered and supplied to the site for final assembly in a building construction. The completed PPVC may be installed similar to precast volumetric concrete on-site. The PPVC modules may be rigged during installation using suitable structures which will be discussed in more detail in relation to Fig. 7. Mating joints used in assembling the PPVC modules on-site may be treated once the PPVC modules are installed. Installation of the PPVC modules may include applying minor architectural finishes and forming mechanical, electrical and plumbing (MEP) inter-connections between modules. Since the PPVC modules are substantially finished (i.e. nearly completed), mating works/treatments should be quick and minor.

[0039] The below table (Table 1) compares a productivity of each major activity for building construction using a conventional method and PPVC according to embodiments of the invention. It may be noted, in particular, that an overall productivity of the conventional method (i.e. a method involving components of the building fabricated on-site) is lower at less than 75% of the productivity of the PPVC (on-site & off-site). As shown in Table 1 , there is: (i) an increase of productivity for PPVC (on-site) method compared to the conventional method by about 38%; (ii) an increase of productivity for PPVC (off-site) method compared to the conventional method by about 44%; and (iii) an increase of productivity for PPVC (on-site and off-site) method compared to the conventional method by about 41 %. This table is tabulated based on a typical dwelling unit with an area of 90m ² .

Table 1 0] Fig. 3 shows an illustration of a PPVC module 300 with six walls in accordance with an embodiment of the invention. A main body 302 comprising a floor 304, four walls 305 and a ceiling 306 of the PPVC module is fabricated using concrete, preferably pre-cast concrete. The PPVC module may comprise at least one partition wall 308 where the at least one partition wall 308 may be fabricated using drywall partition boards. A facade 310 and an end wall 312 may be fabricated using pre-cast concrete, light weight concrete or an appropriate drywall. In particular, all materials used in the fabrication of the PPVC module meets all statutory requirements and there is a complete quality check system in place to ensure proper execution of all trades in the PPVC production process. The PPVC module fabricated complies with current building control standards and other international standards. Moreover, the PPVC module manufactured may be designed to fit onto available trailers (e.g. trailers suitable for Singapore roads). For PPVC modules of special sizes, special trailers with escorts may be deployed. Necessary permits (e.g. oversized vehicle movement permits) may also be applied for prior to transportation of these PPVC modules to the site.

[0041] Fig. 4 shows an illustration of load-transfer in a PPVC column and beam system in accordance with an embodiment of the invention. The PPVC system of the present invention is restrained vertically by bars in columns of the PPVC modules and laterally by connecting plates used in connecting PPVC modules laterally. As shown in Fig. 4, imposed and dead loads (e.g. a weight of concrete used in walls of a PPVC module etc.) within each PPVC module are transferred to floor slabs and beams of the PPVC module and are supported by vertical columns 402 in the PPVC column and beam system. In addition, lateral wind loads 404 may be transferred by lateral means 406 (e.g. beams and/or connecting plates operationally connected between columns of PPVC modules) to a lift core 408 of the building. The load-bearing columns and beams system employed advantageously enhances the structural performance of a building compared to a conventional load-bearing shear wall system since it improves lateral load transfer (e.g. due to wind or earthquake etc.).

[0042] Fig. 5, comprising Figs. 5A and 5B, shows illustrations of applying protection to a PPVC module in accordance with an embodiment of the invention.

[0043] Fig. 5A shows an illustration of a finished PPVC module in a factory off-site prior to application of protective films/layers/covers. As shown in Fig. 5A, a soil stack opening 502, glass and window frames 504, and a side opening 506 (e.g. door frame) of the PPVC module may require protection to prevent them from being damaged.

[0044] Fig. 5B shows an illustration of a PPVC module completed with protection. For example, the soil stack 502 is covered by a removable metal cover 508, the glass and window frames 504 are covered by at least a layer of vinyl film 510, and the side opening 506 is covered by a removable vinyl canvass 512. The protection is applied to the exterior and interior of the PPVC module before transportation and installation/assembly on-site. The applied protection serves to prevent interior finishes and fittings of the PPVC module from damaging during transportation and/or installation on-site. Although not shown in the figure, all interior finishing of the PPVC module may also be protected.

[0045] Fig. 6 shows an illustration of different types of facade available for a PPVC module 300 in accordance with embodiments of the invention. Depending on a design of the building to be constructed, different external facade (e.g. a window and air-conditioning ledge 602, a connecting corridor 604, a curtain/wall cladding 606, a wall and door 608, and/or a balcony 610) may be installed on a PPVC module 300 and protected appropriately off-site.

[0046] Table 2 as shown below shows a minimum level of completion for each element of a PPVC module off-site in accordance with embodiments of the invention. All PPVC modules manufactured may comply with a minimum level of completion as shown below.

Table 2

[0047] Fig. 7 shows an illustration of lifting of a PPVC module in accordance with an embodiment of the invention. In an embodiment, the completed PPVC module is installed in a similar manner as a precast concrete component at site. The completed PPVC module may be rigged in a suitable conventional manner (e.g. using reinforced anchors and/or lifting lugs) to allow the PPVC module to be lifted up for assembly on-site. In an embodiment, the completed PPVC module is lifted by a rigging frame 702. A design of the rigging frame 702 may take into consideration (i) a structural stability of the rigging frame 702, and (ii) a centre of gravity (CG) of the PPVC module and its weight. The design of the rigging frame 702 may be checked and endorsed by a relevant professional engineer to ensure that necessary safety regulations are met. In an embodiment, installation of the PPVC modules comprises a critical drop-in method. The choice of an appropriate lifting equipment is critical in lifting the PPVC modules for assembly on-site. For example, a tower crane with a suitable capacity may be chosen for lifting of PPVC modules in a construction of high-rise buildings. Moreover, tower crane lifting of PPVC modules is to be carefully planned and executed to ensure safety during lifting of the PPVC modules. In an embodiment, heavier PPVC modules are positioned nearer to a mast of the tower crane while lighter PPVCs are positioned further from the mast during lifting.

[0048] Providing a safe working environment for workers on-site is of paramount importance.

In this regard, Fig. 8 shows steps of a method for providing safety barricades on a PPVC module in accordance with an embodiment of the invention.

[0049] In a step 802, a plurality of cast-in provisions are provided on a roof of the PPVC module. The plurality of cast-in provisions enable safety barricades to be mounted on the roof of the PPVC module.

[0050] In a step 804, a plurality of safety barricades are secured to the roof of the PPVC module using the plurality of cast-in provisions provided in the step 802. The safety barricades facilitate a safe working condition for the workers on the roof of the PPVC module. This is important since most if not all critical drop-down works involved in assembling PPVC modules on-site are conducted on the roof of the PPVC module. Levelling works between vertically stacked PPVC modules may also be conducted on the roof of the PPVC module.

[0051] Fig. 9 shows an illustration of a PPVC module fitted with safety barricades 904 using cast-in provisions 902 in accordance with an embodiment of the invention.

[0052] Fig. 10 shows an illustration of a plurality of PPVC modules fitted with safety barricades 904 using cast-in provisions in accordance with an embodiment of the invention. In an embodiment where a plurality of PPVC modules are stacked side by side as shown in Fig. 10, the safety barricades can be freely arranged to form a perimeter along the edges of the PPVC modules. All of the installed safety barricades can be dismounted easily at any time to allow further stacking of PPVC modules on top of an existing level of PPVC modules.

[0053] Fig. 1 1 , comprising Figs. 1 1A and 11 B, shows illustrations of lateral connections between adjacent PPVC modules in accordance with an embodiment of the invention. Fig.

11A shows a cross-sectional plan view of four laterally connected PPVC modules. Lateral connections may be applied onto the load-bearing columns 1 102 of adjoining PPVC modules. Fig. 11 B comprises a perspective view of the four laterally connected PPVC modules in Fig. 1 1A and a blown-up illustration of the lateral connections used in joining two of the adjacent PPVC modules. Each lateral connection may comprise: (i) a bar 1104 provided in each cavity of the load bearing column, (ii) at least one spacer 1106 which is placed onto a recessed area formed by a combination of recessed edges of the adjoining

PPVC modules, and (iii) a connecting plate 1108 and a coupler 1 110 for each bar 1 104. In some embodiments, the bar 1 104 is a continuity bar. An embodiment of a method for laterally connecting two adjacent PPVC modules is discussed below in relation to Fig. 12. [0054] Fig. 12 shows steps of a method 1200 for connecting two PPVC modules laterally in accordance with an embodiment of the invention. The method 1200 may be repeated to connect a plurality of PPVC modules laterally.

[0055] In a step 1202, a second PPVC module (or another PPVC module) is aligned adjacent to a first PPVC module. In particular, at least one load-bearing column of the second module is aligned adjacent to a load-bearing column of the first PPVC module such that a lateral connection may be applied across these two columns. Once the two PPVC modules (i.e. a first and a second PPVC modules) are suitably adjacent to each other (e.g. within permitted error margins), a rod may be provided and placed in a gap between the PPVC modules. In some embodiments, the rod provided is a backer rod. A sealant may be applied subsequently at a top of the gap above the rod to cover the gap between the PPVC modules.

[0056] In a step 1204, a bar is provided in a cavity of each column of the two PPVC modules.

The cavity may be aligned substantially vertically along a length of the column. The bars are designed to take tensile loads and accidental loads in accordance with national and/or international standards (e.g. design code SS EN1991-1-7:2009). The bars ensure continuity between PPVC modules vertically for vertical transfer of loads to a foundation of the building. The bar may be made of steel.

[0057] In an optional step 1206, at least one spacer may be provided. The at least one spacer may comprise one or more shim plates. The at least one spacer may be positioned in an area of recess formed by a combination of recessed edges at a top of the adjoining PPVC modules. The at least one spacer may be used to improve floor level evenness between vertically stacked PPVC modules which will be discussed in more detail in relation to Fig. 28.

[0058] In a step 1208, a connecting plate is provided between the continuity bars where the connecting plate is operationally connected to the continuity bars of the PPVC modules. The connecting plate may be positioned on top of the at least one spacer if the at least one spacer is provided in the step 1206. The connecting plate is used as a lateral restraint and is designed to take shear forces and compressive forces due to lateral loads in accordance with national and/or international standards (e.g. design code SS EN 1991 -1-7:2009). The connecting plate may be made of steel.

[0059] In a step 1210, at least one coupler is provided at a top end of each of the continuity bars of the PPVC modules. The at least one coupler, together with the continuity bars, form a vertical continuity system which enables PPVC modules to be joined vertically in the construction of a building. This is discussed in more detail in relation to Figs. 22 to 26. [0060] In a step 1212, a grout is provided to fill each of the cavities of the PPVC modules. The grout may be a non-shrink grout. In some embodiments, the grout covers the connecting plate. This advantageously prevents exposure of the connecting plate to air, thereby minimises potential corrosion to the connecting plate and ensures effective lateral load transfer.

[0061] In a step 1214, a mortar bedding is provided between the continuity bars of the PPVC modules atop the connecting plate where the mortar bedding is operationally connected to the at least one coupler (and thereby is also connected to the continuity bars) provided in the step 1210. In an embodiment, the mortar bedding is positioned on top of the grout which covers the connecting plate.

[0062] Figs. 13 to 20 depict a series of illustrations showing steps of the method 1200 for connecting two PPVC modules laterally in accordance with an embodiment of the invention.

[0063] Referring to Fig. 13, an illustration of a backer rod and a sealant provided in a gap between two adjacent PPVC modules is shown in accordance with an embodiment of the invention. As shown in Fig. 13, a rod 1302 (e.g. a backer rod) is provided and is placed in a gap between the PPVC modules. A suitable sealant 1304 may then be applied to at a top of the gap to cover the rod 1302 and the gap between the PPVC modules. The sealant aids to prevent water ingress between the adjacent PPVC modules during assembly on- site and/or after the building is completed.

[0064] Fig. 14 shows a perspective view of a plurality of PPVC modules where a rod and a sealant are applied along a perimeter (marked with thickened lines 1402) of a common area between two adjacent PPVC modules in accordance with an embodiment of the invention.

[0065] Referring to Fig. 15, an illustration of a gap between two adjacent PPVC modules 1501 with a rod (e.g. a backer rod) and a sealant is shown. An area of recess 1502 is formed by a combination of recessed edges at a top of the two adjacent PPVC modules 1501 when the PPVC modules are positioned side-by-side. In some embodiments, a corrugated pipe may be placed within each cavity 1503 of each column 1504 of the adjacent PPVC modules 1501. A rod 1506 (shown as a cross-section here in Fig. 15) may be placed horizontally in a gap between the PPVC modules 1501 and covered by a sealant 1508 which is applied at a top of the gap. The rod may be placed in a direction parallel to a length of the top of the PPVC modules 1501. In some embodiments, the rod may be placed along an entire perimeter near the edge of an adjoining area between the two adjacent PPVC modules 1501 (e.g. as shown in Fig. 14). [0066] Fig. 16 shows an illustration of a bar 1602 (e.g. a continuity bar) provided in each cavity 1503 of each column 1504 of the PPVC modules 1501 in accordance with an embodiment of the invention (see e.g. the step 1204 of Fig. 12). The distance D as shown in Fig. 16 provides an indication of a threading depth of the bar in a coupler (see e.g. in Fig. 18) used in connecting bars of vertically stacked PPVC modules. For example, if the bar is not threaded into the coupler properly, D will be larger than twice a diameter of the bar. This indicates an insufficient threading depth. In contrast, if D is equal to twice a diameter of the bar, it indicates a sufficient threading depth. In some embodiments, it is sufficient to thread the bar to a depth of about a diameter of the bar to ensure a sufficient threading depth. Note, in this embodiment, the bar 1602 is threaded and the cavity 1503 is provided by an internally corrugated pipe (not shown).

[0067] Fig. 17 shows an illustration of two spacers 1702 and a connecting plate 1704 between the bars 1602 of the PPVC modules 1501 in accordance with an embodiment of the invention (see e.g. the steps 1206 and 1208 of Fig. 12). As shown in Fig. 17, the two spacers 1702 are placed on each side of the two adjacent PPVC modules 1501 and in the area of recess 1502. The connecting plate 1704 is placed on top of the two spacers 1702 between the bars of the adjacent PPVC modules and is connected to the bars. In an embodiment, the connecting plate 1704 is placed within the area of recess 1502 (i.e. below a top level of the roofs of the PPVC modules) as shown in Fig. 17.

[0068] Fig. 18 shows an illustration of a coupler 1802 on each bar in each cavity 1503 of the PPVC modules 1501 in accordance with an embodiment of the invention (see e.g. the step 1210 of Fig. 12). The coupler 1802 is fastened to a top end of each bar 1602. In this way, the bars 1602 are placed under tension by the coupler 1802 (e.g. in a case where bottom ends of the bars 1602 are also fastened to another set of couplers 1802 attached to a pair of bottom PPVC modules). In this set-up, the two spacers 1702 are under compression by the connecting plate 1704 which is locked in place by the coupler 1802.

[0069] Fig. 19 shows an illustration of a grout 1902 filling each of the cavities 1503 of each column 1504 and covering the connecting plate 1704 in accordance with an embodiment of the invention (see e.g. the step 1210 of Fig. 12). The grout 1902 may be a non-shrink grout. As shown in Fig. 19, the grout covers each of the column 1504, the two spacers 1702 and the connecting plate 1704. As such, the connecting plate 1704 is fully covered by the grout. This may be checked visually during inspection.

[0070] Fig. 20 shows an illustration of a mortar bedding 2002 between the bars 1602 in accordance with an embodiment of the invention (see e.g. the step 1212 of Fig. 12). The mortar bedding 2002 may be a high-strength metal plate. As shown in Fig. 20, the mortar bedding 2002 is placed atop the connecting plate 1704 and on top of the grout 1902. The mortar bedding 2002 is operationally connected to each of the couplers 1802 at each end of the bars 1602.

[0071] Fig. 21 shows steps of a method 2100 for filling a gap between two adjacent PPVC modules using a rod and a sealant in accordance with an embodiment of the invention.

[0072] In a step 2102, a rod is provided in a gap between the PPVC modules. The rod may be placed in a direction parallel to a length of a top of the adjacent PPVC modules. In some embodiments, the rod may be placed along an entire perimeter near the edge of an adjoining area between the two adjacent PPVC modules (see e.g. Fig. 14).

[0073] In a step 2104, a sealant may be applied at a top of the gap and may cover the rod provided in the step 2102. The sealant may be water-proof. The application of the sealant advantageously prevents water ingress during assembly of PPVC modules on-site and/or after the building is completed.

[0074] Fig. 22 shows steps of a method 2200 for connecting PPVC modules vertically in accordance with an embodiment of the invention. The method 2200 may be repeated to connect a plurality of PPVC modules vertically.

[0075] In a step 2202, another two adjacent PPVC modules are aligned above the two adjacent PPVC modules (see e.g. in Fig. 20). In this case, each column of the another two adjacent PPVC modules is positioned onto a respective column of the PPVC modules below.

[0076] In a step 2204, a bar (similar to the bars 1602 provided in the step 1204 of Fig. 12) is provided into a cavity of each column of the two upper PPVC modules. In some embodiments, where corrugated pipes are provided in the cavities of the columns of the upper PPVC modules, the bars are inserted into the corrugated pipes in the columns.

[0077] In a step 2206, each bar provided in its respective cavity of each column of each of the upper PPVC modules is fastened to its respective coupler using a bottom end of the bar. In some embodiments, fastening the bar of the upper PPVC modules to its respective coupler involves screwing the bar with a torque wrench or a screw-driver.

[0078] In a step 2208, a grout is provided into each cavity of each column of the upper PPVC modules. The grout may be a non-shrink grout. In some embodiments, the entire column is filled with grout up to a top end of the column. In some embodiments, it is not necessary to fill the entire column of the upper PPVC modules with grout.

[0079] Figs. 23 to 26 depict a series of illustrations showing steps of the method 2200 for connecting PPVC modules vertically in accordance with an embodiment of the invention. [0080] Referring to Fig. 23, an illustration of another two adjacent PPVC modules 2302 aligned above the PPVC modules 1501 of Fig. 20 is shown. The mortar bedding 2002 installed in the step 1214 now takes up an air space between the upper and the lower PPVC modules. In some embodiments where corrugated pipes are provided in columns 2304 of the upper PPVC modules 2302 (i.e. the another two adjacent PPVC modules), the corrugated pipes are aligned to the couplers 1802 which are fixedly connected to the top end of the bars 1602 in the cavities 1503 of the columns 1504 of the two adjacent PPVC modules below such that each coupler 1802 is fitted into a bottom end of each of the corrugated pipes. In some embodiments where corrugated pipes are not provided, the upper PPVC modules 2302 are aligned with the PPVC modules below such that each coupler 1802 is fitted into a bottom end of each column 2304 of the upper PPVC modules 2302.

[0081] Fig. 24 shows an illustration of bars 2402 provided in cavities 2403 of the columns 2304 of the another two adjacent PPVC modules 2302 in accordance with an embodiment of the invention. The bars 2402 are fastened to its respective coupler 1802 using a bottom end of the bar 2402. In some embodiments, fastening the bar 2402 to its respective coupler 1802 involves screwing the bar 2402 with a torque wrench or a screw-driver from a top end of the bar 2402. To ensure that the bar 2402 is tightened or inserted into its respective coupler 1802 by a suitable distance 2404, which corresponds to a protrusion length that can be measured at a top of the upper PPVC modules, is measured. This is shown in more detail in relation to Fig. 25. In some embodiments, the distance 2404 is about twice a diameter of the bar 2402. In other embodiments, the distance 2402 is of a similar magnitude as the diameter of the bar 2402. In some embodiments, the distance 2402 is about one and a half times the diameter of the bar 2402.

[0082] Fig. 25 shows an illustration of bars 1602, 2402 provided in the cavities 1503, 2403 of the columns 1504, 2304 of four PPVC modules 1501 , 2302 used in connecting the four PPVC modules 1501 , 2302 in accordance with an embodiment of the invention. As shown in Fig. 25, a length of the bar 2502 may be same as a height 2504 of the PPVC module. In this case, it may be straight-forward to inspect critical parameters in relation to installation of the bars 1602, 2402 in each PPVC module 1501 , 2302 using the methods 1200, 2200 for PPVC modules assembly. For example, as discussed in Fig. 24 and shown here in Fig. 25, a protrusion length 2506 measured from a top of the upper PPVC modules 2302 corresponds to the distance 2404 that the bar 2402 has inserted into its respective coupler 1802 of the PPVC modules 1501 below.

[0083] Fig. 26 shows an illustration of a grout 2602 filling each of the cavities 2403 of the columns 2304 of the another two adjacent PPVC modules 2302 in accordance with an embodiment of the invention. This grouting sequence eliminates the high pressure resulting from pouring of the grout along the entire height (approximately 3m) of the PPVC module to the bottom of the PPVC module 2501. For example, in shear walled designs, a large part of a wall between two PPVC modules will be filled with a substantial volume of grout. This may result in an overwhelming pressure which may result in bulges in the shear walls. In contrast, the grout is contained inside the cavities of the load bearing columns in the present method, and may therefore eliminate any pressure issues posed by the grout.

[0084] Upon assembly of the PPVC modules, inspection may be performed to determine if the PPVC modules have been connected up to desired standard laterally and/or vertically. In some embodiments, borescope inspections are performed at horizontal spaces and/or vertical spaces between the PPVC modules. For performing inspections in the horizontal spaces, inspection holes (e.g. with a diameter of 25mm) may be provided at a ceiling of a PPVC module. The inspection holes may be covered by plugs. These plugs may be removed for accessing the horizontal spaces during inspections. A borescope inspection of horizontal spaces between PPVC modules may involve checking of unlikely water seepages, and gap spaces between vertically stacked PPVC modules (e.g. lookout for spalling concrete between walls, columns, beams and slabs etc.). For an inspection of the vertical spaces, a hole maybe provided through a flooring between two adjoining PPVC modules. The hole may allow inspection of the sealant 1508, the rod 1506, and the gap between the two adjoining PPVC modules. The hole may be patched up with putty after the inspection.

[0085] Fig. 27 shows an illustration of a cross-sectional view of eight PPVC modules 2702 in accordance with an embodiment of the invention. A method of ensuring alignment or evenness of floor finishes between upper and lower PPVC modules will be discussed in relation to an enlarged diagram of an intersection 2704 of four PPVC modules 2706 as shown in Fig. 28.

[0086] Fig. 28 shows an illustration of connecting joints at the intersection 2704 of four PPVC modules 2706 in accordance with an embodiment of the invention. As shown in Fig. 28, an upper PPVC floor 2802 is supported on a lower PPVC ceiling 2804 by a spacer 2806. Another similar upper PPVC floor 2808 is also supported on another lower PPVC ceiling 2810 by another spacer 2812. The spacers 2806, 2812 may comprise at least one shim plate. In some embodiments, a plurality of spacers 2806, 2812 are placed between the upper PPVC floors 2802, 2808 and the lower PPVC ceilings 2804, 2810. A floor level between the two upper PPVC slabs 2802, 2808 may be adjusted and levelled by using the plurality of spacers 2806, 2812. For example, if the upper PPVC floor 2808 is higher than that of the upper PPVC floor 2802, a height of the plurality of spacers 2810, 2812 may be reduced to level the two PPVC floors 2802, 2808 (e.g. by decreasing a number of spacers 2806, 2812). Once the floors 2802, 2808 of the upper PPVC modules are levelled, floor finishes 2814 may be laid across the floors of the two upper PPVC modules 2802, 2808.

[0087] Fig. 29 shows a cross-sectional view of two vertically stacked PPVC modules 2902, 2904 in accordance with an embodiment of the invention. As shown in Fig. 29, an upper PPVC module 2902 is positioned above a lower PPVC module 2904. Interior finishing of the PPVC modules 2902, 2904 are also shown. For example, mechanical and electrical (M&E) connections 2906 have been installed above a false ceiling 2908. There are also dry wall partitions 2910 placed within each of the PPVC modules 2902, 2904. A soil shaft 2912 and a soil pipe 2914 are also present in each of the PPVC modules 2902, 2904. The soil shaft 2912 may be enclosed by suitable drywall partitions (see e.g. Fig. 34 for more detail). Depending on a location of the soil shaft 2912, water-proofing of the soil shaft may be provided. When the upper PPVC module 2902 is stacked above the lower PPVC module 2904, it is important to ensure that the soil shaft 2912 and an opening for the soil pipe 2914 between the PPVC modules 2902, 2904 are aligned properly within error margins. An enlarged diagram showing an intersection 2916 between the two PPVC modules is shown in Fig. 30.

[0088] Fig. 30 shows an enlarged view of a cross-section of two vertically stacked PPVC modules 2902, 2904 in accordance with an embodiment of the invention. As shown in Fig. 30, the soil pipe 2914 passes through the two vertically stacked PPVC modules 2902, 2904. In the intersection 2916 around the soil pipe, a floor 3002 of the upper PPVC module 2902 is stacked above a ceiling 3004 of the lower PPVC module 2904 with a ring gasket 3006 placed between the floor 3002 and the ceiling 3004. The ring gasket 3006 is positioned adjacent to an edge of an opening through which the soil pipe 2914 passes through between the upper PPVC module 2902 and the lower PPVC module 2904. This advantageously helps to prevent any water seepage from the soil pipe 2914 if necessary. The ring gasket 3006 may be made of rubber.

[0089] Fig. 31 , comprising Figs. 31 A, 31 B and 31 C, shows illustrations of mechanical, electrical and plumbing (MEP) services and a false ceiling provided between adjacent PPVC modules in accordance with an embodiment of the invention. After adjacent PPVC modules are joined using the method 1200 as discussed, it is necessary to connect at least some of the interior finishing between adjacent PPVC modules.

[0090] Fig. 31A shows MEP services termination 3102 and false ceiling termination 3104 of the two adjacent PPVC modules. [0091] After the adjacent PPVC modules are in position, connection of the MEP services can be done on-site. Connected MEP services 3106 between the two adjacent PPVC modules is shown in Fig. 31 B. Electrical services may follow a path along a connecting corridor above false ceilings between PPVC modules and may branch off to other parts of the PPVC modules. The services may be extended to suitable locations for power points, lights switches, data points etc. on walls of the PPVC modules via vertical conduits embedded if necessary.

[0092] Fig. 31 C shows a completed false ceiling 3108 provided between the two adjacent PPVC modules. The completion of the false ceiling can be carried out after the MEP services are connected as shown in Fig. 31 B. Access openings may be provided in the false ceiling for purposes of maintenance.

[0093] For long-term performances of PPVC modules, considerations on possible differential movements between joining corridors (e.g. a corridor formed by different PPVC modules in Fig. 32) need to be taken into account. This is of particular importance for floor finishing and wall finishing of PPVC modules. To account for these differential movements in regards to the floor finishing, additional connecting plates 1704 may be provided between adjacent PPVC modules for floors with connecting openings (e.g. a corridor) before laying of the floor finishing. To take into account of differential movements for wall finishing, fibre- glass mesh tapes may be used to lap over a vertical joint connecting the adjoining PPVC modules before applications of wall plastering, skimming or compound jointing.

[0094] Figs. 32 to 34 illustrate water-proofing between adjacent PPVC modules. Referring to Fig. 32, a plan view of a cross-section of four laterally connected PPVC modules is depicted in accordance with an embodiment of the invention. As shown in Fig. 32, the four PPVC modules comprises an en-suite master bedroom PPVC module 3202, a PPVC module 3204 with a bedroom and a common bathroom, a PPVC module 3206 with a bedroom and a kitchen and a living room PPVC module 3208. Areas in the bathrooms (e.g. in the PPVC modules 3202 and 3204) and the kitchen (e.g. in the PPVC module 3206) may be considered as wet areas as they are often exposed to a presence of water. To elucidate measures taken for water-proofing these wet areas between adjacent PPVC modules, a cross section of the PPVC modules 3202, 3204 and 3206 along a line 3210 is shown in Fig. 33.

[0095] Fig. 33 shows a plan view of a cross-section view of three laterally connected PPVC modules 3202, 3204 and 3206 in accordance with an embodiment of the invention. Water seepage may be prevented from occurring between the PPVC modules 3202, 3204 and 3206 through use of a water-proofing treatment (shown as thickened lines 3302 along portions of the walls in the PPVC modules 3202, 3004, 3206) in the wet areas of adjacent PPVC modules. In some embodiments, the PPVC modules 3202, 3204 and 3206 are completely compartmentalized by concrete walls which aids to minimise water seepage between adjacent PPVC modules.

[0096] Fig. 34 shows an illustration of dry and wet areas partitioned in a PPVC module in accordance with an embodiment of the invention. Drywall partition boards 3402 may be installed on each side of a partition which serves to divide space in a PPVC module. The drywall partition boards 3402 may comprise a fire resistance plasterboard. The thickness of the drywall partition boards 3402 may range from 10mm to 20mm. If partition is required between a dry area and a wet area within a PPVC module, an additional layer of waterproof partition board 3404 may be used. In addition, a suitable sealant 3406 lining a bottom part of the water-proof partition board 3404 and around a bottom corner to beneath a floor tile surface of the PPVC module may be applied to prevent water seepage (the suitable sealant may be similarly applied in the water-proofing treatment shown in Fig. 33) between the wet and dry areas within the PPVC module. Skirting 3408 may be applied to a bottom of the partition if necessary to cover a joint between the partition and a floor of the PPVC module. In order to install the partition, a bottom track 3410 may be fitted to a desire area of the floor where the partition is to be erected. In some embodiments, an acoustic sealant 3412 is applied beneath the bottom track 3410. The bottom track 3410 may be secured to the floor using fasteners 3414. Studs (or support frames) 3416 may then be constructed and placed onto the bottom track as shown in Fig. 34. The studs 3416 functions as a frame where partition boards 3402, 3404 may be mounted. In some embodiments, insulation 3418 is fitted within the partition. Wall tiles 3420 may be adhered to the partition boards if it is required (e.g. for the wet area as shown in Fig. 34).

[0097] In some embodiments, materials used for dry wall partitions, false ceilings are non- combustible. The materials may have achieved appropriate fire-test performance reports and certificates. In some embodiments, bodies of PPVC modules are made of a precast concrete of grade 40 and above, and is non-combustible. PPVC modules comprising six walls and fabricated using concrete may therefore allow containment of a fire within a dwelling unit made of a PPVC module and prevent spreading of the fire to other dwelling units. In some embodiments, the concrete structure of a PPVC module has a fire rating of 1 - 2 hours. Dwelling units made of concrete PPVC modules may sustain a minimal damage due to a fire. As such, unlike steel-based PPVCs, inspection of an integrity of a building structure may not be required in a building made of concrete PPVCs.

[0098] Fig. 35 shows an illustration of a roof deck 3500 constructed at a top of a plurality of PPVC modules in accordance with an embodiment of the invention. The roof deck 3500 may be constructed after the necessary PPVC modules have been assembled on-site. The roof deck 3500 comprises stumps 3502 placed above columns of the PPVC modules. The stumps 3502 may function to support roof slabs 3504 and may be made of concrete. One or more roof slabs 3504 are placed onto the stumps 3502 to form a top surface of the roof deck 3500. The roof slabs 3504 may be made of concrete. Water-proofing treatments may be carried out on the roof slabs 3504 to improve durability of the roof deck against external weather elements. The roof deck 3500 formed in this manner advantageously comprise an air gap 3506 between the PPVC modules and the roof slabs 3504. The air gap 3506 acts as an insulation to minimise temperature fluctuations (e.g. as a result of direct heating from the sun in a summer or cooling by fallen snow in a winter) experienced by top-most PPVC modules directly beneath the roof deck 3500. A parapet 3508 may also be installed along a perimeter of the roof deck 3500. The parapet 3508 may act as safety barriers for maintenance work and/or use to facilitate installation of a removable gondola frame for cleaning works performed on a facade of the building. 9] Whilst the foregoing description has described exemplary embodiments, it will be understood by those skilled in the art that many variations of the embodiments can be made within the scope of the present invention as defined by the claims. Moreover, features of one or more embodiments may be mixed and matched with features of one or more other embodiments.