LESSONS FROM USING BIM TO INCREASE DESIGN

1 LESSONS FROM USING BIM TO INCREASE
2 DESIGN-CONSTRUCTION INTEGRATION
3 Gregory P. Luth, M.ASCE1; Alyssa Schorer, M.ASCE2; Yelda Turkan, M.ASCE3
4 Abstract
5 Building Information Modeling (BIM) has started to become a common practice in the Architectural,
6 Engineering, Construction and Facilities Management (AEC-FM) Industry. The benefits of BIM have
7 been recognized in the AEC-FM industry, and numerous design firms and contractors reported benefits of
8 utilizing BIM in their projects. However, the full potential of BIM tools has not yet been achieved. In
9 current practice, design and construction phases are not well integrated. Conventional practice is to
10 produce a conceptual design based on no particular construction sequence, means or methods.
11 Construction knowledge must be deployed to support design. This way, the full potential of BIM can also
12 be exploited. The term High Definition Building Information Modeling (HiDef BIM) is used to describe
13 BIM that is detailed and precise enough to create shop drawings directly from the model. Additionally,
14 the use of HiDef BIM offers the opportunity to examine construction sequence in order to produce a
15 design that can be less expensive, save time, and be of a higher quality. This paper explores the benefits
16 of utilizing HiDef BIM and the lessons learned through a case study.
17 18 19 Keywords: High Definition Building Information Modeling (HiDef BIM), Construction Sequence,
20 Integrated Project Delivery (IPD).
1
President, Ph.D., S.E., Gregory P Luth & Associates (GPLA), 3350 Scott Blvd, Bldg 48, Santa
Clara, CA 95054. Email: greg@gplainc.com
2
Design Engineer, M.S., P.E., Gregory P Luth & Associates (GPLA), 3350 Scott Blvd, Bldg 48,
Santa Clara, CA 95054. Email: alyssa@gplainc.com
3
Assistant Professor, Ph.D., Department of Civil, Construction and Environmental Engineering, Iowa
State University, 428 Town Engineering Building, Ames, Iowa 50011-3232. Email: yturkan@iastate.edu
1 21 Introduction
22 Current design and construction processes must change in order to get maximum benefit from the
23 latest design tools and technologies. Building Information Modeling (BIM) is one of the latest
24 technologies that have changed how the Architectural, Engineering, Construction and Facility
25 Management (AEC-FM) industry does business. BIM is defined as a digital representation of physical
26 and functional characteristics of a facility (National BIM Standards, 2007). It is reported in previous
27 research that utilizing BIM improves processes and supports decision making throughout the life cycle of
28 a project by enabling accurate and rapid update of design changes and integration of life-cycle data
29 (National BIM Standards, 2007; Becerik-Gerber and Rice, 2010; Staub-French and Khanzode, 2007;
30 Arayici et al. 2011). The benefits of BIM have been recognized in the AEC-FM industry, and numerous
31 design firms and contractors reported the benefits of utilizing BIM in their projects. However, the full
32 potential of BIM technology has not yet been achieved.
33 In current practice, design and construction phases are not well integrated. Conventional practice
34 is to produce a conceptual design based on no particular construction sequence, means or methods.
35 Therefore, currently BIM models are created based on approximate design intent, and used for clash
36 detection, or worse, simply provided as a requirement of the contract, whether useful or not. In order to
37 take full advantage of BIM tools, the design model should be detailed and precise enough to create shop
38 drawings. This requires incorporating construction means, methods and sequencing knowledge into the
39 design model, i.e. construction knowledge must be employed to support design. In this paper, authors use
40 the term High Definition BIM (HiDef BIM) to describe BIM that is created at a shop drawing level of
41 detail. HiDef BIM has been employed on several Gregory P. Luth & Associates (GPLA) projects, and its
42 benefits have been substantial.
43 44 The following section summarizes the significant progress that has been made toward virtual
design and construction using BIM tools while identifying remaining knowledge gaps. The subsequent
2 45 section reviews relevant concepts related to HiDef BIM and Integrated Project Delivery. Then, one of the
46 GPLA projects is presented as a case study and benefits of using HiDef BIM are evaluated.
47 Literature Review
48 The benefits of BIM have been recognized in the AEC-FM industry, and numerous design firms
49 and contractors reported the benefits of utilizing BIM in their projects. Previous research results reported
50 that utilizing BIM improves processes and supports decision making throughout the life cycle of a project
51 by enabling accurate and rapid update of design changes and integration of life-cycle data (Arayici et al.
52 2011; Becerik-Gerber and Rice, 2010; National BIM Standards, 2007; Kvan, 2000; Ku et al., 2008;
53 Staub-French and Khanzode, 2007; Young et al., 2009). Furthermore, the benefits related to the
54 preconstruction phase, which includes enabling prefabrication, and identification of design conflicts prior
55 to construction, were reported by several researchers (National BIM Standards, 2007; Shen & Issa, 2010;
56 Staub-French and Khanzode, 2007). However, the full potential of BIM technology has not yet been
57 achieved.
58 BIM is becoming a common practice in the AEC/FM industry, and the potential benefits of BIM
59 are much talked about. However, there is still a need for understanding the value added by BIM for
60 construction projects. BIM usage for all stages of a project is not yet a common practice. Therefore, there
61 have been numerous case studies identifying the benefits, and testing the capabilities and limitations of
62 BIM (Barlish and Sullivan 2012; Sacks and Barack, 2008; Succar, 2009).
63 While BIM benefits are vital to quantify, it is also very important to identify its level of detail
64 (LoD) to achieve the planned value added by its usage. Various researchers stated that BIM model’s LoD
65 depends on the application, such as creating shop drawings, energy simulations, cost estimating, clash
66 detection etc., it will be used for (Eastman et al., 2008; Fischer and Kunz, 2003; Staub-French and
67 Khanzode, 2007). A study by Leite et al, (2011) showed that more detail in a model does not necessarily
68 mean more modeling work. Futhermore, they concluded that such additional effort can actually lead to
69 higher precision, better supporting decisions during design and construction.
3 70 HiDef BIM and Integrated Project Delivery (IPD) with HiDef BIM
71 Conventional practice is to create a conceptual design and model based on no particular
72 construction sequence or means or methods. The ubiquitous use of “typical details” is meant to provide a
73 generic scenario that supposedly allows the project to be completed in full; however, situations invariably
74 arise where the typical solution is ill-suited or impossible to build given the conditions. This leads to
75 RFI’s, change orders, construction delays, and a lot of paperwork. Subcontractors bid a fixed price based
76 on incomplete design details since final quantities are not known until after shop drawings, and because
77 the “typical details” are not easily translated into material lists and labor estimates. Therefore, they have
78 to cover risk in price, and often get away with charging more for changes that the designer did not
79 anticipate.
80 IPD with HiDef BIM is based on a complete design product based on the most efficient
81 construction sequence. Unit price is based on exact quantities in the model and adjusted based on the
82 actual quantities delivered. It gives an advantage to the subcontractor with the most efficient and cost
83 effective way to fabricate and deliver. This requires incorporating detailed construction knowledge and
84 planning into the design.
85 There are two major ways in which a design professional can influence BIM on his or her project.
86 The first is internally, within his or her own design. The second is project wide, requiring collaboration
87 between many parties. Ideally, this includes involving those responsible for the construction of the
88 building early on in the project. Input not only from the contractor, but from the subcontractors who
89 fabricate and place the parts, is the ultimate collaboration tool. Unfortunately, it is not always possible to
90 involve all critical parties at the time of design, in which case the responsibility falls on the engineer to
91 produce a conscious and efficient design. HiDef BIM requires the structural engineer to pose questions
92 not only about his or her own structure, but about the other elements of the building as well such as
93 mechanical, electrical, plumbing, fire proofing, and other special systems. Any engineer can anticipate a
94 construction sequence within their own design. This requires experience as well as a little out-of-the-box
95 thinking in order to solve some of the most frequent and simple problems. For example, consider a
4 96 building of steel and precast concrete. Is it designed in such a way that some steel must be erected, then
97 all of the precast, and then further steel must be connected to embeds in the precast? Is there a better way
98 to design the structure so that the steel erector does not have to make multiple appearances in the
99 schedule? A building may fulfill all building code requirements, but it is also very important that it
100 fulfills a logical construction sequence. Designing a structure that allows each subcontractor to complete
101 his or her job without depending on another trade is a good example of using construction sequence to
102 create an intelligent design.
103 HiDef BIM success is defined by the benefit it brings to the project. Having a BIM model is only
104 effective if it is being used, and the more team players that use it, the more value it can add to the project.
105 This is where the “HiDef” part of the concept comes in. A mechanical contractor can create a 3D model
106 for his or her design to clash detect between his or her own systems. This model becomes more useful
107 when it is shared with the other trades: the structural engineer, for example, can coordinate where ducts
108 penetrate stud walls using the mechanical 3D model. Knowing where penetrations are would allow each
109 stud to be modeled, sized and spaced appropriately around penetrations. Furthermore, having each stud
110 modeled accurately leads to the possibility of running a materials report that is correct, and not estimated
111 with 20% overages. Accurate stud models also make it possible to create shop drawings from the design
112 model.
113 The case study that follows will go into greater detail of how HiDef BIM can have a significant
114 impact on a project; the key is that the more information that goes into the model, the more opportunity
115 the team has to reap a benefit. It takes discipline and ingenuity to orchestrate a cooperative atmosphere,
116 and the alternative is no longer affordable or practical. Design intent should be to deliver shop drawings
117 by the time the contract is awarded.
118 Case study
119 The University of Southern California (USC) School of Cinematic Arts consists of six buildings
120 constructed in three phases, and Gregory P Luth & Associates (GPLA) is the structural engineering firm
5 121 for all six buildings. The owner specified that the buildings must be Venetian stucco, with no joints,
122 which would require a concrete substrate. GPLA was also committed to maintaining an efficient
123 construction schedule on par with a steel structure. GPLA used Tekla Structures to model the entire
124 project in 3D.
125 In order to erect the buildings as quickly as possible, the main building frame was designed to be
126 structural steel, with braces at the stair wells which enabled the structure to withstand lateral loads before
127 installation of the concrete shear walls on the exterior. Furthermore, this also allowed for quick steel
128 erection of one entire building giving the interior trades the opportunity to begin working immediately
129 while the more time intensive concrete shear walls were poured. The concrete shear walls are “rocking
130 wall” panels that fit between steel columns, with an innovative design to connect them to the steel
131 structure. “Butterfly plates fuses” were welded to the steel columns and plates in strategic locations that
132 had welded hoops that were cast into the walls at a later time. The “butterfly plates” are designed to yield
133 along their perforations in order to minimize the damage done to the structure’s integrity and appearance
134 during a seismic event. In a worst case scenario, an interior wall could be opened up to replace the
135 damaged plates. This method exploits ingenuity in order to improve design and to deliver an aesthetically
136 pleasing product that performs unparalleled to others. Moreover, it also made use of BIM which allowed
137 each embed and rebar to be placed exactly where they needed to be.
138 The second way in which concrete wall construction was sped up, without sacrificing quality, was
139 to use pre-fabricated rebar mats. GPLA created the BIM model in such detail that it was possible to
140 produce shop drawings of the rebar mats, accompanied by barlists. Prefabrication would not have been
141 possible without modeling the exact rebar placement around embeds and penetrations. Moreover, stick-
142 building these complex shear walls would have been a debilitating time sink in the schedule.
143 A third use of BIM in this project that stands out as an exemplary use of 3D technology to
144 improve construction is the panelization of the light gauge panels for the complex hip and valley roof.
145 GPLA designed the light gauge roof connections to the main steel frame in such a way that panels could
146 be made ahead of time in the shop and simply lifted into place on site. Not only was time saved through
6 147 both rebar and light gauge detailing, but also the prefabricated materials were manufactured at a higher
148 standard of quality under a controlled environment, as opposed to stick-building on site where conditions
149 are often changing or uncertain. Furthermore, installation of prefabricated assemblies tends to put
150 construction crews at less risk, which is another welcome benefit of employing BIM models on a project.
151 Employing IPD and BIM technology are simply contractual obligations to some firms within the
152 AEC-FM industry. Currently, the most common way of employing BIM technology is to create 3D
153 models for each trade, and to use them for clash detection after the design is finalized. Clash detection
154 itself already indicates that something in the process has failed. Clashes can be avoided before the final
155 design if the trades exchange information during the design process. Clash detection is a passive use of
156 BIM rather than proactive, and the ultimate goal should not be only to avoid a pipe hitting a beam. The
157 ultimate goal should be discovering a way to build faster, less expensive, and safer. In order to achieve
158 the full potential of BIM technology, it should be utilized throughout the entire construction process, i.e.
159 from design to field.
160 What is the journey of the rebar from the shop to the field?
161 In order to provide fully detailed rebar at the USC School of Cinema, GPLA had to examine the
162 whole rebar fabrication process. GPLA began by tracing each step of the project that involved rebar;
163 essentially, the journey of a piece of rebar, from the time it is cut and bent to the moment it is buried in
164 concrete and finally a part of a building. Along each step of the journey that the rebar is modified or
165 moved, GPLA had to consider whether that process could be made easier, or improved. GPLA examined
166 the following when deciding the most efficient way to improve certain processes:
167 
How does the rebar fabricator read the bar sizes and shapes into a machine?
168 
What sizes and shapes does he prefer to make?
169 
What sizes and shapes can be lifted by a single man, or two men?
170 
What sizes and shapes can be transported conveniently?
171 
How is the rebar unloaded from the truck?
7 
172 How is it lifted into place?
173 The answers to these questions informed the whole process from design, to detailing, and to shop
174 drawings. Along the way, issues arose where something could have been a little different or a little better,
175 and those are the lessons learned that must be remembered, so the right questions are asked the next time.
176 GPLA produced bar lists exported directly from Tekla to MS Excel, which were formatted to be
177 read into Soulé, the system that fabricates the rebar. Tekla Structures offers many forms of customization,
178 so that the information in the database of the building model can be extracted in a variety of ways and
179 formats. Having a BIM model that can be easily viewed or exported to other file formats is vital;
180 otherwise the value in BIM would be null.
181 The next step was to detail the rebar so that it could be pre-fabricated where possible. The
182 foundations were detailed with 30’-0” bars wherever possible since that was a readily available stock
183 length. The basement wall cages (Figure 1) were designed to be 25’-0” wide maximum as requested by
184 the foreman, so that they could be lifted into place on site with minimal equipment. Each cage had a set of
185 splice bars tied to them which were used to splice the wall horizontals once the next cage was in place
186 (Figure 2). Additionally, the basement walls are riddled with embeds for columns and rocking walls
187 above, and steel beams that form the first floor. A large amount of congestion meant that bar layering and
188 spacing was absolutely critical. The HiDef BIM model deployment on this project allowed any
189 difficulties to be identified ahead of time and resolved with a clear detail, rather than discovering these
190 problems during placement (Figure 3). Details shown in these figures were produced directly from the
191 HiDef BIM model, as are all details shown in this paper.
8 192 193 194 195 196 Figure 1: An example of a rebar shop drawing detail that exactly specifies how the rebar are
layered in order to coordinate the placement of embeds and penetrations in the basement walls at
USC.
197 198 199 200 201 202 Figure 2: Detail from a rebar shop drawing at USC, showing where two typical prefabricated
basement wall mats come together at a corner with a prefabricated corner cage. Loose splice bars
are indicated where the wall horizontals are spliced between mats and cages. Note that bar layering
is critical so that cages may fit within one another and still allow room for top-of-wall embeds.
9 203 204 205 206 207 208 209 Figure 3: USC site photo of placed rebar at a similar condition to the shop drawing shown in Figure
2. Note the embed at top-of-wall, which was designed to fit efficiently within the rebar layers. At
corners especially, using a HiDef BIM model to produce rebar was essential to identify difficulties
ahead of time, and avoid any delays in the field.
210 window openings in different locations. Moreover, all the wall panels have butterfly plate embeds and
211 heavily reinforced boundary elements. GPLA wanted the rocking walls to be constructed quickly, but
212 with the utmost attention to accuracy. After getting the rebar foreman’s feedback, it was determined that
213 the easiest way to build the cages would be to fabricate them in a shop. The widths of the walls were
214 chosen during schematic design to be small enough for shipping on a truck bed, and they could be stacked
215 in a pile onto a truck in the order they would be placed, so that the pile would not be shuffled once on site.
216 The order the wall barlists were released mimicked the order of the wall construction. Whether a wall had
217 openings or not, the wall horizontal and vertical bars were modeled continuous, and all the loose bars
218 needed to slide through embeds were tied to the cages. The HiDef BIM model actually had two sets of
219 rebar – one for “as detailed” for the fabricator and one “as designed” for permit drawings. Each bar in the
The rocking wall cages are the most complex rebar on this particular job. Many of the walls have
10 220 wall cages was specifically dimensioned so that when the cage arrived, it would fit perfectly around steel
221 members and embeds. In order to make the openings, once a cage was placed, the horizontal and vertical
222 bars were trimmed according to the dimensions of the opening. A bundle of u-bars to lap the cut bars
223 were on hand when needed. This was achieved by simply exporting two separate Excel sheets for barlists
224 from Tekla Structures software. The fabricators requested that the wall cages be in one list with the
225 opening u-bars omitted, and a second bar list for the u-bars alone. This streamlined the fabrication process
226 so bars that were tied into cages together were made together, and the extra bars added in were in their
227 own package. There were two lessons learned from the wall cages installation. The first lesson was
228 related to cage lifting. Procedure for this operation was not initially discussed. Nevertheless, just before
229 the shop drawing process began, GPLA was able to add two #10 horizontal bars on each wall (Figure 4),
230 as requested by the foreman. These extra bars served as pick points for the crane (Figure 5). The second
231 lesson learned was to have early conversations with those responsible for building the project. During
232 construction of the first and second phases of the project, the wall cages lifted in to place had to be
233 shimmed up to “float” so they did not rest on the basement walls below. By the third phase of the project,
234 the foreman mentioned that having a way to shim the rebar panels built in ahead of time would save time
235 for him. His suggestion was to space the horizontal ties in the boundary elements more closely around the
236 wall embeds at the steel columns, so the panels could “hang”. GPLA incorporated this request into the
237 detailing of the third phase, and this simple change made for quicker, easier construction. (Figure 6). This
238 lesson learned was a convincing reminder of the importance of examining each step of construction, and
239 involving those who are responsible for that step.
11 240 241 242 243 244 Figure 4: This is a shop drawing detail from the rocking wall rebar cages. The exact spacing of the
horizontal and vertical bars is given, as well as the necessary embed bars. The #10 bars labeled
“Pick bars” are the additional bars added for the crane to lift the cage. The dotted lines indicate the
surrounding steel structure that the wall cage must fit around.
12 245 246 247 Figure 5: A rocking wall prefabricated rebar cage being lifted into place by a crane at USC. Each
wall cage was installed in a matter of minutes, rather than hours or days of stick-building.
13 248 249 250 251 252 Figure 6: A site photo of a rocking wall rebar cage before the window opening has been cut. Note
the closely spaced ties around the hoop embeds on either side, from which the cage hangs.
253 would have been to stick build the congested rebar and wait on an RFI every time something was unclear.
254 However, it is known that on Phase I changing the sequence from a floor-by-floor approach to building
255 the steel structure in its entirety first, and then building the exterior walls while completing the interior
256 MEP work saved in excess of 6 months. The preconstruction personnel at the construction company
257 estimated and scheduled the project using the former methodology even though the structure was
It is difficult to quantify the savings for this part of the job since the alternative to prefabrication
14 258 designed based on the latter approach. The general superintendent communicated with the engineer about
259 the schedule to make him aware that the latter approach was the basis of design. Therefore, the new
260 schedule was created based on the new methodology and compared with the previous schedule which
261 indicated more than 6 months of time saving.
262 A similar occurrence happened with the rebar which was bid based on a stick-built process. The
263 rebar foreman agreed to try the prefabrication method, and he tested 5 prefabricated panels several weeks
264 ahead of his scheduled start date. The schedule was based on stick-building 1 panel a day, and there were
265 65 panels. Nonetheless, he brought out 5 panels and had them installed in 3 hours. The general
266 contractor immediately flipped his sequence, and put the rebar ahead of all other sequences. The rebar
267 was completed in 6 weeks less time than was allocated in the schedule – with 50% of savings.
268 Additionally, the team was able to achieve a quality product in a controlled shop environment rather than
269 struggling with complicated reinforcement and embeds on site.
270 The light gauge detailing on USC Phase 3 also has some quantifiable data that shows the use of
271 HiDef BIM improved the project. GPLA attended a meeting with the metal fabricators before the
272 detailing began, and at first the pre-construction team decided not to use panelization and stay with the
273 traditional stick building. Once the idea of panelization trickled down to the field team, the idea was
274 revisited and chosen as the method for construction. Collaboration among the teams led to the
275 modification of the original eave detail that GPLA had initially designed. The fabricator also agreed that
276 having a few typical details for the connections was a good choice; for example, typical details for screw
277 patterns between panels which would be the same throughout the roof.
278 Again, the journey of the light gauge pieces from the point of fabrication to their completed
279 placement in the structure was considered in an attempt to streamline all aspects of the process. Each
280 panel would have a materials list on the sheet, so the pieces could be cut at the mill with minimal material
281 waste. Tekla Structures has the capability of recognizing panel assemblies that are the same and creating a
282 tally for each panel type. Panels were held to a width of 10’-0” for transportation purposes. The eaves
283 were built directly into the panels so that they were set down in one self-contained piece to form the
15 284 whole roof structure. Blocking was built into the panels where they attached to the main structure to
285 provide a surface to screw to (Figure 7). The panels even had the majority of the plywood sheathing
286 installed in the shop. GPLA also planned for a 1/8” tolerance between each panel.
287 GPLA learned the most important lesson by watching the panels get erected. First, a truck would
288 arrive with a load of panels, which had to be offloaded so they could be “prepped” for lifting. This step
289 was necessary because no pick points or means of lifting had been incorporated into the shop drawings,
290 and the team was forced to fasten the pick points to the panels while they were on the ground (Figure 8).
291 292 293 294 295 296 Figure 7: A screenshot from Tekla Structures showing one light gauge roof panel. Note the blocking
for attachment is already built in (pink members). Additionally, the eave detail at the bottom edge
is already included, so each panel is an all-inclusive piece of roof.
297 off the truck if they had come with pick points. Unloading the panels took eight men one hour, and
298 erecting each panel took 8 – 10 minutes (Figure 9). The superintendent estimated that had the panels
299 come prepped for lifting, the time would be cut in half for each panel. Indeed, Tekla Structures software
300 has the capability of locating the center of gravity of each panel. The pick points must be located at a
301 precise location in order for the assembly to hang at the proper angle for installation. The 3D technology
The fabricator believes that the panels could have been lifted by the crane and installed straight
16 302 that Tekla offers makes it a relatively trivial exercise to locate the precise location for the pick point on
303 each panel during shop drawings preparation, and GPLA can incorporate this into future shop drawings.
304 305 306 307 308 Figure 8: A close-up of a roof panel pick point, installed by workers on-site. GPLA could have
streamlined the roof installation by incorporating pick points in their shop drawings, which would
be installed ahead of time.
17 309 310 311 312 313 314 315 Figure 9: On-site photo from roof panel installation at USC. Shop crews labeled each panel
according to a key plan provided by GPLA (this panel is labeled LR-8). Note that while the roof is
installed, only two men were required to be on top of the roof structure, making this installation
safer than a stick-built roof, which would require upwards of 10 men in harnesses.
Time & cost savings
316 In a post-construction discussion with the steel team who fabricated and installed the roof panels,
317 a lot of the benefits and savings were brought to light. One of the most important benefits was that rather
318 than having 10 – 12 men in harnesses stick building the roof, there were 2 or 3 men guiding the panels
319 into place, making the process much safer. The use of scaffolding was avoided, as well as the time it
320 would have taken to set it up and break it down. The panels were built in a controlled area with less
321 expensive labor. There were also significant material savings. The panel contractor used GPLA’s shop
322 drawings and bill of materials which allowed them to cut almost everything right at the mill, and to
323 deliver the pieces in bundles for the typical panels. Furthermore, there were also important time savings: a
324 relatively inexperienced apprentice could sort the cut pieces in much less time than cutting them from a
325 long stock.
18 326 The superintendent also provided GPLA with a constructive list of what could be done
327 differently. He pointed out that the panel pick points being pre-installed rather than field installed would
328 save time. He also stated that the 12 gauge metal is difficult to screw in the field and a lot of screws were
329 stripped and wasted. Preferably, next time the design would be in a lighter gauge. Additionally, in some
330 cases the 1/8” tolerance was not quite enough when panels had to sandwich between hard points on either
331 end. The best solution would be to brainstorm some type of adjustable tolerance connection. The team
332 also found that a 35’-0” length of panel is the ideal maximum length that could be easily handled.
333 Anything larger might require a larger crane that would “eat away” at any savings. Lastly, he indicated
334 that if the MEP hanger locations could be coordinated ahead of time, the blocking for those attachments
335 could also be done in the shop.
336 Conclusions and Lessons Learned
337 Perhaps the most rewarding benefit is seeing figures in writing of the savings. This is the sell
338 point BIM needs. However, benefits of BIM are often hard to quantify on paper. While GPLA firmly
339 believes that HiDef BIM leads to a better product and a faster, safer construction schedule, there is rarely
340 a cut-and-dry analysis that can prove it.
341 The light gauge superintendent provided GPLA information on how the panelization process
342 benefitted his company. His estimate for erecting the light gauge via a traditional stick-built method was
343 between 190 and 210 man-days from start to finish. The actual time spent was 80 man-days, and this
344 could be reduced further if some of the productivity lessons learned had been incorporated earlier. GPLA
345 spent approximately 185 hours modeling and producing shop drawings for the roof panels. This being the
346 first time GPLA had the opportunity to detail light gauge panels, it can only be assumed that the process
347 will get even shorter in the future. Based on the figures above, and rates provided by the superintendent,
348 the steel contractor saved in the range of $54,000 - $63,700 on labor alone. Additional material savings,
349 human safety savings, and the savings from pre-installing the sheathing are not factored into this number.
350 GPLA spent approximately $23,000 to detail the job and to create the shop drawings, which is well below
19 351 the amount saved by the contractor. The savings for this type of job can only increase if the lessons
352 learned are applied to the next project. Consulting with the experts of each specific trade and sharing
353 construction knowledge across the team will benefit the process in an exponential way.
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