DESIGN ANALYSIS OF LOW COST MULTI STORED

DESIGN AND ANALYSIS OF LOW COST MULTI STORED BUILDING USING STAAD PRO Abstract This paper aims to point out the various aspects of prefabricated building methodologies for low cost school building by highlighting the different prefabrication techniques, and the economical advantages achieved by its adoption In a building the foundation, walls, doors and windows, floors and roofs are the most important components, which can be analyzed individually based on the needs thus, improving the speed of construction and reducing the construction cost The major current methods of construction systems considered here are namely, structural block walls, mortar less block walls, prefabricated roofing components like precast RC planks, precast hollow concrete panels, precast concrete/Ferro cement panels are considered.low cost school building design using Staad pro vi8 Keywords: Prefabrication; Precast RCC „kular‟, precast joist, Ferro cement products ,Staad pro vi8 METHODOLOGY Introduction of low cost Multi Storedbuilding ,Planning and designing of school building design with transfer girder and floating columns as per architect requirement using Staad Pro Vi8 software CASE CASE Analyzing the structural frame with Analyzing the structural frame with floating floating piers as a whole for design loads piersbased on sequence of constructionfor (DL, LL, WL, SL) design loads (DL, LL) and structure as a whole for WL and SL Comparison of the variation in deformations and forces for the transfer girdersand the frame which is above the transfer girders Finalising the Low Cost Multi Storeddesign forces for the transfer girders and frame Conclusion Introduction Affordable housing is a term used to describe dwelling units whose total housing cost are deemed “Affordable” to a group of people within a specified income range In India, the technology to be adopted for housing components should be such that the production and erection technology be adjusted to suite the level of skills and handling facilities available under metropolitan, urban and rural conditions Logical approach for optimizing housing solutions: There should be a logical approach for providing appropriate technology based on the availability of options, considering its technical and economical analysis There should be optimal space in the design considering efficiency of space, minimum circulation space Economy should be considered in design of individual buildings, layouts, clusters etc While preparing the specifications it should be kept in mind that, cost effective construction systems are adopted Energy efficiency has gained considerable importance due to energy crisis especially in developing countries Orientation, built–form, openings & materials play a vital role besides landscaping / outdoor environment To develop an effective mechanism for providing appropriate technology based shelter particularly to the vulnerable group and economically weaker section.(R.K.Garg, 2008) Prefabrication as applied to `Low Cost School Building(P.K.Adlakha and H.C.Puri, 2002) Advantages of prefabrication are: In prefabricated construction, as the components are readymade, selfsupporting, shuttering and scaffolding is eliminated with a saving in shuttering cost ACSGE-2009, Oct 25-27, BITS Pilani, India In conventional methods, the shuttering gets damaged due to its repetitive use because of frequent cutting, nailing etc On the other hand, the mould for the precast components can be used for large number of repetitions thereby reducing the cost of the mould per unit In prefabricated housing system, time is saved by the use of precast elements which are casted off-site during the course of foundations being laid The finishes and services can be done below the slab immediately While in the conventional in-situ RCC slabs, due to props and shuttering, the work cannot be done, till they are removed Thus, saving of time attributes to saving of money In precast construction, similar types of components are produced repeatedly, resulting in increased productivity and economy in cost too Since there is repeated production of similar types of components in precast construction, therefore, it results in faster execution, more productivity and economy In prefabricated construction, the work at site is reduced to minimum, thereby, enhancing the quality of work, reliability and cleanliness The execution is much faster than the conventional methods, thereby, reducing the time period of construction which can be beneficial in early returns of the investment Concept of prefabrication / partial prefabrication has been adopted for speedier construction, better quality components & saving in material quantities & costs Some of these Construction techniques &Materials for walls, roof & floor slab, doors & windows are as follows: In Walls:In the construction of walls, rammed earth, normal bricks, soil cement blocks, hollow clay blocks, dense concrete blocks, small, medium and room size panels etc of different sizes are used However, bricks continue to be the backbone of the building industry In actual construction, the number of the bricks or blocks that are broken into different sizes to fit into position at site is very large which results in wastage of material poor quality Increasing the size of wall blocks will prove economical due to greater speed and less mortar consumption, which can be achieved by producing low density bigger size wall blocks using industrial wastes like blast furnace slag and fly ash Several prefabrication techniques have been developed and executed for walls but these medium and large panel techniques have not proved economical for low rise buildings as compared to traditional brick work (P.K.Adlakha and H.C.Puri, 2002) i Non erodible mud plaster: The plaster over mud walls gets eroded during rains, which necessitates costly annual repairs This can be made non erodible by the use of bitumen cutback emulsion containing mixture of hot bitumen and kerosene oil The mixture is pugged along with mud mortar and wheat/ rice straw This mortar is applied on mud wall surface in thickness of 12 mm One or two coats of mud cow dung slurry with cutback are applied after the plaster is dry The maintenance cost is low due to enhanced durability of mud walls.(R.K.Garg, 2008) Fig Mud Plastered House ii Fly –Ash sand lime bricks: By mixing of lime and fly ash in the presence of moisture, fly ash sand lime bricks are made Fly Ash reacts with lime at ordinary temperature and forms a compound possessing cementitious properties After reactions between lime and fly ash, calcium silicate hydrates are ACSGE-2009, Oct 25-27, BITS Pilani, India Produced which are responsible for the high strength of the compound Bricks made by mixing lime and fly ash are therefore, chemically bonded bricks The bricks are manufactured with the help of hydraulic press and are dried in the autoclave These bricks have various advantages over the clay bricks, It possesses adequate crushing strength, uniform shape, smooth finish and does not require plastering and also are lighter in weight than ordinary clay bricks (R.K.Garg, 2008) iii Solid concrete and stone blocks: This technique is suitable in areas where stones and aggregates for the blocks are available locally at cheaper rates Innovative techniques of solid blocks with both lean concrete and stones have been developed for walls The gang-mould is developed for semi-mechanized faster production of the blocks In the manual process, single block moulds are used wherein the concrete is compacted with help of a plate vibrator With the use of a portable power screw driven egg laying type machine, solid concrete blocks are made with higher productivity at low cost Six blocks of 30 x 20 x cm size are cast in single operation with an output of 120-150/hr (R.K.Garg, 2008) In Floor and Roof: Structural floors/roofs account for substantial cost of a building in normal situation Therefore, any savings achieved in floor/roof considerably reduce the cost of building Traditional Cast-in-situ concrete roof involve the use of temporary Shuttering which adds to the cost of construction and time Use of standardized and optimized roofing components where shuttering is avoided prove to be economical, fast and better in quality Some of the prefabricated roofing/flooring components found suitable in many low-cost housing projects are: i Precast RC Planks ii Prefabricated Brick Panels iii Precast RB Curved Panels iv Precast RC Channel Roofing v Precast Hollow Slabs vi Precast Concrete Panels vii L Panel Roofing viii Trapezon Panel Roofing ix Un reinforced Pyramidal Brick Roof i Precast RC plank roofing system: This system consists of precast RC planks supported over partially precast joist RC planks are made with thickness partly varying between cm and cm There are haunches in the plank which are tapered When the plank is put in between the joists, the space above cm thickness is filled with in-situ concrete to get tee-beam effect of the joists A cm wide tapered concrete filling is also provided for strengthening the haunch portion during handling and erection The planks have numbers mm dia MS main reinforcement and mm dia @ 20 cm centre to centre cross bars The planks are made in module width of 30 cm with maximum length of 150 cm and the maximum weight of the dry panel is 50 kg (Figure 2) Precast joist is rectangular in shape, 15 cm wide and the precast portion is 15 cm deep (Figure 2) The above portion is casted while laying insitu concrete over planks The stirrups remain projected out of the precast joist Thus, the total depth of the joist becomes 21 cm The joist is designed as composite Tee-beam with cm thick flange comprising of cm precast and cm in-situ concrete (Figure 3) This section of the joist can be adopted up to a span of 400 cm For longer spans, the depth of the joist should be more and lifting would require simple chain pulley block The completely finished slab can be used as intermediate floor for living also In residential buildings, balcony projections can be provided along the partially precast joists, designed with an overhang carrying super imposed loads for balcony as specified in IS: 875-1964, in addition to the self load and the load due to balcony railings The main reinforcement of the overhang provided at the top in the in-situ concrete attains sufficient strength The savings achieved in practical implementations compared with conventional RCC slab is about 25%.(P.K.Adlakha and H.C.Puri, 2002) ACSGE-2009, Oct 25-27, BITS Pilani, India Fig Precast R.C Planks Fig Fig R.C Planks laid over partially precast joists R.C Planks laid over partially precast joists ii Prefabricated brick panel roofing system: The prefabricated brick panel roofing system consists of: (a) Prefab brick panel Brick panel is made of first class bricks reinforced with two MS bars of mm dia and joints filled with either 1:3 cement sand mortar or M-15 concrete Panels can be made in any size but generally width is 53 cm and the length between 90 cm to120 cm, depending upon the requirement The gap between the two panels is about cms and can be increased to cms depending upon the need A panel of 90 cm length requires 16 bricks and a panel of 120 cm requires 19 bricks (Figure 4) (P.K.Adlakha and H.C.Puri, 2002) (b) Fig Brick Panel (b) Partially precast joist It is a rectangular shaped joist 13 cm wide and 10 cm to 12.5 cm deep with stirrups projecting out so that the overall depth of joist with in-situ concrete becomes 21 cm to 23.5 cm, it is designed as composite Tee-beam with 3.5 cm thick flange (Figures and ) (P.K.Adlakha and H.C.Puri, 2002) Fig Precast R C Plank and Joist System Fig Details of Precast Joist Structural design The prefab brick panel for roof as well as for floor of residential buildings has two numbers mm dia MS bars as reinforcement up to a span of 120 cms The partially precast RC joist, is designed as simply supported Tee-beam with 3.5cm thick flange The reinforcement in joist is provided as per design requirements depending upon the spacing and span of the joist ACSGE-2009, Oct 25-27, BITS Pilani, India 283 WEIGHT 209.25 284 WEIGHT 184.49 285 WEIGHT 210.49 286 WEIGHT 169.47 287 WEIGHT 414.89 288 WEIGHT 339.38 289 WEIGHT 318.58 290 WEIGHT 393.12 291 WEIGHT 404.38 292 WEIGHT 409.99 293 WEIGHT 400.32 294 WEIGHT 165.31 295 WEIGHT 183.86 296 WEIGHT 200.85 297 WEIGHT 145.44 298 WEIGHT 158.27 299 WEIGHT 159.85 300 WEIGHT 163.63 301 WEIGHT 104.65 302 WEIGHT 191.06 303 WEIGHT 164.64 304 WEIGHT 433.22 305 WEIGHT 193.61 306 WEIGHT 40.39 307 WEIGHT 51.63 308 WEIGHT -53.6 309 WEIGHT -21.45 310 WEIGHT 36.9 311 WEIGHT 62.52 312 WEIGHT -69.04 313 WEIGHT -26.64 314 WEIGHT 39.03 315 WEIGHT 47.81 316 WEIGHT -28.5 317 WEIGHT 62.33 318 WEIGHT 61.95 319 WEIGHT 62.5 320 WEIGHT 85.15 321 WEIGHT -27.21 322 WEIGHT 62.38 323 WEIGHT 40.61 324 WEIGHT 43.28 325 WEIGHT 69.16 326 WEIGHT -28.78 327 WEIGHT -28.41 328 WEIGHT 42.14 329 WEIGHT 39.01 330 WEIGHT 37.05 331 WEIGHT 40.95 332 WEIGHT 98.96 333 WEIGHT 114.67 334 WEIGHT 98.85 335 WEIGHT 114.78 336 WEIGHT 98.93 337 WEIGHT 114.7 338 WEIGHT 100.14 339 WEIGHT 114.88 340 WEIGHT 102.63 341 WEIGHT 112.39 342 WEIGHT 104.85 343 WEIGHT 110.17 344 WEIGHT 25.22 345 WEIGHT 28.08 346 WEIGHT 28.3 347 WEIGHT 24.1 348 WEIGHT 22.12 349 WEIGHT 23.43 350 WEIGHT 23.39 351 WEIGHT 22.02 352 WEIGHT 57.17 353 WEIGHT 57.92 354 WEIGHT 55.23 355 WEIGHT 49.19 DEFINE WIND LOAD TYPE INT 1.2 HEIG 21.5 EXP JOINT 26 TO 158 160 TO 239 242 244 TO 246 248 TO 259 261 262 264 TO 270 273 TO 2839 LOAD LOADTYPE Seismic TITLE SEISMIC LOAD: X 1893 LOAD X LOAD LOADTYPE Seismic TITLE SEISMIC LOAD: -X 1893 LOAD X -1 LOAD LOADTYPE Seismic TITLE SEISMIC LOAD: Z 1893 LOAD Z LOAD LOADTYPE Seismic TITLE SEISMIC LOAD: -Z 1893 LOAD Z -1 LOAD LOADTYPE Wind TITLE WIND LOAD @ X WIND LOAD X TYPE LOAD LOADTYPE Wind TITLE WIND LOAD @ -X WIND LOAD X -1 TYPE LOAD LOADTYPE Wind TITLE WIND LOAD @ Z WIND LOAD Z TYPE LOAD LOADTYPE Wind TITLE WIND LOAD @ -Z WIND LOAD Z -1 TYPE LOAD LOADTYPE Dead TITLE DEAD LOAD SELFWEIGHT Y -1 LIST TO 49 51 53 TO 55 57 TO 59 61 TO 296 299 TO 310 312 313 TO 459 461 463 TO 474 476 TO 481 483 TO 512 523 TO 705 711 TO 1451 MEMBER LOAD 293 TO 296 299 TO 301 323 396 TO 402 423 496 TO 502 523 528 TO 532 537 538 543 TO 549 618 TO 624 635 640 TO 644 649 650 655 TO 661 UNI GY -2.2 *LOAD LOADTYPE Dead TITLE DEAD LOAD OF OUTER WALL EWIGHT @ 2.5 M HEIGHT & 0.51 BEAM DEPTH MEMBER LOAD 102 103 105 106 116 117 119 TO 124 127 128 130 131 133 135 147 174 175 177 178 188 189 191 TO 196 199 200 202 203 205 207 219 UNI GY -8.78 *LOAD LOADTYPE Dead TITLE DEAD LOAD OF OUTER WALL EWIGHT @ 2.5 M HEIGHT & 0.74 BEAM DEPTH MEMBER LOAD 134 136 206 208 UNI GY -7.77 *LOAD LOADTYPE Dead TITLE DEAD LOAD OF OUTER WALL EWIGHT @ 2.5 M HEIGHT & 0.61 BEAM DEPTH MEMBER LOAD 139 141 TO 143 211 213 TO 215 UNI GY -8.34 109 140 181 212 UNI GY -4.17 *LOAD LOADTYPE Dead TITLE DEAD LOAD OF INNER WALL EWIGHT @ 2.5 M HEIGHT & 0.3 BEAM DEPTH MEMBER LOAD 125 132 144 TO 146 148 197 204 216 TO 218 220 UNI GY -4.85 *LOAD LOADTYPE Dead TITLE DEAD LOAD OF OUTER WALL EWIGHT @ M HEIGHT & 0.45 BEAM DEPTH MEMBER LOAD 246 247 249 250 260 261 263 TO 268 271 272 274 275 277 279 283 285 TO 287 291 302 306 307 310 318 321 349 350 352 353 363 364 366 TO 371 374 375 377 378 380 382 386 388 TO 390 394 403 407 408 411 418 421 UNI GY -11.26 *LOAD LOADTYPE Dead TITLE DEAD LOAD OF OUTER WALL EWIGHT @ M HEIGHT & 0.51 BEAM DEPTH MEMBER LOAD 255 281 304 312 358 384 405 412 449 TO 453 455 457 463 TO 471 480 494 527 3275 3277 3279 3281 3283 3285 3287 3289 3291 UNI GY -10.99 *LOAD LOADTYPE Dead TITLE DEAD LOAD OF OUTER WALL EWIGHT @ M HEIGHT & 0.61 BEAM DEPTH MEMBER LOAD 278 280 381 383 456 485 487 UNI GY -10.55 *LOAD LOADTYPE Dead TITLE DEAD LOAD OF INNER WALL EWIGHT @ M HEIGHT & 0.45 BEAM DEPTH MEMBER LOAD 252 TO 254 284 355 TO 357 387 UNI GY -5.63 *LOAD 10 LOADTYPE Dead TITLE DEAD LOAD OF INNER WALL EWIGHT @ M HEIGHT & 0.3 BEAM DEPTH MEMBER LOAD 269 276 288 TO 290 292 314 316 317 319 320 322 372 379 391 TO 393 395 414 416 417 419 420 422 UNI GY -5.96 481 483 UNI GY -9.98 *LOAD 11 LOADTYPE Dead TITLE DEAD LOAD OF INNER WALL EWIGHT @ M HEIGHT & 0.51 BEAM DEPTH MEMBER LOAD 257 259 313 315 360 362 413 415 UNI GY -5.49 *LOAD 16 LOADTYPE Dead TITLE DEAD LOAD OF STAIR CASE HEAD ROOM WT @ 2.5 M & OTER WALL FLOOR LOAD YRANGE 1.5 6.5 FLOAD -5 GY YRANGE 15 18 FLOAD -5 GY *LOAD 23 LOADTYPE Live TITLE LIVE LOAD L4/L5 @ FLOOR LOAD YRANGE 12 FLOAD -3 GY YRANGE 20.5 25 FLOAD -3 GY *LOAD 24 LOADTYPE Live TITLE LIVE LOAD L4/L5 @ FLOOR LOAD YRANGE 12 FLOAD -1 XRANGE -1.5 ZRANGE 20 GY YRANGE 12 FLOAD -1 XRANGE 17.5 19 ZRANGE 20 GY YRANGE 12 FLOAD -1 XRANGE 7.5 10 ZRANGE 2.5 15 GY PERFORM ANALYSIS PERFORM ANALYSIS START CONCRETE DESIGN CODE INDIAN FC 25000 ALL FYMAIN 415000 ALL FYSEC 415000 ALL END CONCRETE DESIGN PERFORM ANALYSIS PERFORM ANALYSIS FINISH ANALYSIS AND DESIGN RESULTS LOW COST MULTI STORED BUILDING Some of the sample analysis and design results have been shown below for beam number which is at the roof level of 1st floor ============================================================================ B E A M N O M25 D E S I G N R E S U LTS Fe415 (Main) LENGTH: 7500.0 mm Fe415 (Sec.) SIZE: 300.0 mm X 600.0 mm COVER: 25.0 mm SUMMARY OF REINF AREA (Sq.mm) -SECTION 0.0 mm 1875.0 mm 3750.0 mm 5625.0 mm 7500.0 mm -TOP 1350.38 350.24 350.24 REINF (Sq mm) (Sq mm) (Sq mm) BOTTOM REINF 350.24 (Sq mm) 402.32 (Sq mm) 350.24 417.24 (Sq mm) 1468.12 (Sq mm) 350.24 (Sq mm) (Sq mm) 350.24 (Sq mm) -SUMMARY OF PROVIDED REINF AREA -SECTION 0.0 mm 1875.0 mm 3750.0 mm 5625.0 mm 7500.0 mm -TOP 12-12í REINF layer(s) BOTTOM 5-10í REINF layer(s) 4-12í 4-12í4-12í layer(s) layer(s) 6-10í 6-10í layer(s) layer(s) 13-12í layer(s) layer(s) 5-10í 5-10í layer(s) layer(s) SHEAR legged 8í legged 8í legged 8í legged 8í legged 8í REINF @ 190 mm c/c @ 190 mm c/c @ 190 mm c/c @ 190 mm c/c @ 190 mm c/c Fig 8.1: Geometry of beam no Fig 8.2: Property of beam no Fig 8.3: Shear bending of beam no Fig 8.4: Deflection of beam no Fig 8.5: Concrete design of beam no ================================================================== C O L U M N N O.34 D E S I G N R E S U L T S M25 Fe415 (Main) Fe415 (Sec.) LENGTH: 4100.0 mm CROSS SECTION: 500.0 mm X 500.0 mm COVER: 40.0 mm ** GUIDING LOAD CASE: 30 END JOINT: 10 SHORT COLUMN REQD STEEL AREA : 3669.89 Sq.mm REQD CONCRETE AREA: 246330.11 Sq.mm MAIN REINFORCEMENT: Provide 12 - 20 dia (1.51%, 3769.91 Sq.mm.) (Equally distributed) TIE REINFORCEMENT: Provide mm dia rectangular ties @ 300 mm c/c SECTION CAPACITY BASED ON REINFORCEMENT REQUIRED (KNS-MET) -Puz : 3913.47 Muz1 : 266.51 Muy1 : 266.51 INTERACTION RATIO: 0.99 (as per Cl 39.6, IS456:2000) SECTION CAPACITY BASED ON REINFORCEMENT PROVIDED (KNS-MET) -WORST LOAD CASE: 30 END JOINT: 10 Puz : 3943.47 Muz : 272.73 Muy : 272.73 IR: 0.96 ================================================================= Fig 8.6: Concrete design of column no 34 Conclusions Low cost school building targets can be achieved by replacing the conventional methods of planning and executing building operation based on special and individual needs and accepting common denominator based on surveys, population needs and rational use of materials and resources Adoption of any alternative technology on large scale needs a guaranteed market to function and this cannot be established unless the product is effective and economical Partial prefabrication is an approach towards the above operation under controlled conditions The essence lies in the systematic approach in building methodology and not necessarily particular construction type or design The methodology for low cost housing has to be of intermediate type- less sophisticated involving less capital investment (P.K.Adlakha and H.C.Puri, 2002) STAAD PRO has the capability to calculate the reinforcement needed for any concrete section The program contains a number of parameters which are designed as per IS: 456(2000) Beams are designed for flexure, shear and torsion Design for Flexure: Maximum sagging (creating tensile stress at the bottom face of the beam) and hogging (creating tensile stress at the top face) moments are calculated for all active load cases at each of the above mentioned sections Each of these sections are designed to resist both of these critical sagging and hogging moments Where ever the rectangular section is inadequate as singly reinforced section, doubly reinforced section is tried Design for Shear: Shear reinforcement is calculated to resist both shear forces and torsional moments Shear capacity calculation at different sections without the shear reinforcement is based on the actual tensile reinforcement provided by STAAD program Two-legged stirrups are provided to take care of the balance shear forces acting on these sections Beam Design Output: The default design output of the beam contains flexural and shear reinforcement provided along the length of the beam Column Design: Columns are designed for axial forces and biaxial moments at the ends All active load cases are tested to calculate reinforcement The loading which yield maximum reinforcement is called the critical load Column design is done for square section Square columns are designed with reinforcement distributed on each side equally for the sections under biaxial moments and with reinforcement distributed equally in two faces for sections under uni-axial moment All major criteria for selecting longitudinal and transverse reinforcement as stipulated by IS: 456 have been taken care of in the column design of STAAD References 1.“Faster Production of Stone Blocks and Concrete Blocks‟, CBRI-Annual Report, 1999-2000 2.Garg R.K., `Sustainable Human Settlements and Cost Effective Housing Technologies.‟ BMTPC 3.Garg R.K., Garg N K &Batra Y K.(2004), Sanitation and Waste Water Disposal Systems inRural Areas, Journal of Indian Building Congress, Vol 11, No 2, 2004; Seminar on “Up gradation of Housing & Amenities in Rural Areas”, Bhubaneswar, December, 22nd-23rd2004 BMTPC Gupta B.S., Jain S.K., Hira B.N “Trapezonpan Roofing/Flooring Scheme”, Indian Concrete Journal, July 1982, India 5.Hira B.N &Negi S.K., Journal of Indian Building Congress, Vol 11, No 2, 2004;Seminar on “Up gradation of Housing & Amenities in Rural Areas”, December, 22nd-23rd2004 at Bhubaneswar Appropriate Building Techniques for Rural Housing BMTPC IS 4326: Earthquake Resistant Design and Construction of Materials, 1993 7.Lal A.K., `Hand Book of Low Cost Housing.‟ National Urban Housing and Habitat Policy, 2007, Govt of India 9.Standards and Specifications for Cost Effective Innovative Building Materials and Techniques.‟ BMTPC 10 Study on Low Cost Incremental Housing for UP State.‟ BMTPCD, Adlakha and Associates 11.Verma N., 1985, CBRI Building Research Note No 34 on Low Cost Sanitation for Rural & Urban Houses ... the analyzing windowLow Cost School Building CHAPTER DESIGN OF LOWCOST MULTI STOREDBUILDING USINGSTAAD.Pro DESIGN OF LOW COST SCHOOL BUILDING USINGSTAAD.Pro The structure was designed for concrete... Introduction of low cost Multi Storedbuilding ,Planning and designing of school building design with transfer girder and floating columns as per architect requirement using Staad Pro Vi8 software... reduce the cost of building Traditional Cast-in-situ concrete roof involve the use of temporary Shuttering which adds to the cost of construction and time Use of standardized and optimized roofing