As a follow up to our previous benefits of BIM blog post, which covered the 10 main benefits of BIM for architects, BSBG Lead Architectural Technologist Mark Vaughan now provides an evaluation of the advantages presented by BIM for contractors…
Everything about BIM lends itself to assuring the project programme is met without delay. It enables a contractor to establish a programme and construction sequence using the design as the starting point. The following factors fall under the category of programming, and should not be overlooked:
With the output speed capabilities that BIM offers, the design period can be substantially reduced. To realise this potential, a client and contractor should consider the BIM capabilities of the designers they are using, as although programmes can be reduced, without care so can the quality of the output. This is one of many reasons BSBG has reached the levels of success it has in BIM – the ability to deliver high quality in short periods.
Currently, the industry does not use phasing to its full potential, and yet this is one of the top features within Revit. As the concept is approaching finalisation, contractors could get more involved with the BIM modelling by working out site logistics and inputting these into the intelligence of the model. This not only helps assure programme success, but also provides safer solutions in line with UK CDM regulations. Inputting logistics into the modelling allows designers to provide earlier guidance and assistance on the site process. This results in contractors having the ability to begin work on site with a far more advanced level of preparedness than we see now in Dubai.
Site co-ordination issues
BIM can detect co-ordination issues early, that might usually only be found on site; due to the limitations of 2D delivery. This facility is all about reducing or eliminating the potential for surprises found on site. However, it is important that contractors understand the processes required to achieve this and respect them. Often, clients/contractors can focus efforts on areas that slow the process of coordination down; an example is in understanding what a clash is.
When a contractor/client requests a clash free model, from an Architectural Technologist’s perspective this is great as it shows the contractor understands the benefits BIM offers. But, developing a true understanding of what a clash is can be disruptive to the process. BSBG received a request to run clash detection on a new window in an SFS wall on a previous project. There is no clash in this scenario as the window sits within the wall. Another example was a request to run a clash detection on MEP pipework insulation against other MEP pipework insulation with a tolerance of 0 mm. We had to explain that insulation is compressible and therefore, not an issue at this tolerance. These examples can be overcome with education, however, designers require a good degree of flexibility in discussions to allow us to provide the necessary solutions to focus efforts on areas of risk.
Good co-ordination is critical for the success of a project. This is not only for time and cost, but for protecting the design intent and delivering the result the client is expecting. By embracing BIM co-ordination, the client’s expectations are protected, and therefore disputes are reduced or avoided. BIM allows for a platform of collaboration across disciplines. It allows for quick and easy interference checks between disciplines and model elements, and therefore informs designers at an earlier stage than traditional methods.
In fact, if we really consider collaboration in BIM, it is simply revolutionary. Traditionally, an architect would be reliant on reviewing every aspect of a project in a 2D plan, then in 2D sections, and then in 2D elevations. It is simply impossible for a designer to draw every single junction within a design in 2D to fully ensure co-ordination. And even if they could, there is the risk of human error. Traditional methods require contractors to take responsibility for more of the co-ordination, and if they can’t protect the intent, they run the risk of complicating relationships with the client.
In addition, contractors will tender a project based on the information available. Often this is priced from 2D deliverables, whether it be traditional or BIM methods. What traditional methods don’t offer is assurance to the contractor that they will not incur more cost due to co-ordination issues found during construction. Therefore, a contractor can tender a project produced in BIM with more confidence.
BIM offers much more besides detailed models, such as the platform it creates for the propagation of knowledge and insight for those involved in the project. It’s a platform that acts as an enabler for effective collaboration. Contractors are able to develop the most effective method of delivery using digital engineering – comprised of data on the building’s design, the construction plan and its purpose. We can build it together digitally, which makes the physical build much more efficient.
BSBG promotes the idea of close collaboration between contractor and architect to achieve this. Collaboration across servers like C4R is great for time and efficiency, but there is no substitute for regular meetings to engage with the entire team, present the BIM modelling, explain the design, and agreeing upon actions within the 3D platform. At present BSBG, utilises Navis Works to its full potential to review the status of co-ordination within a meeting and to mark up the 3D project. Navis Works is great for taking notes within meetings and ensuring there is no confusion.
Traditionally, contractors are very reliant on the output promised to them by designers. BIM enables contractors to integrate new services and solutions into their current business model, from the development of BIM execution plans, modelling and quality procedures, to takeoff reports and work breakdown structure. This can provide contractors with more insight and control, but they may need to adjust their business models to make the most of its capabilities.
Most contractors using BIM will already have integrated the key aspects into their working practices, however, it is contractors/developers such as Laing O’Rourke and Lendlease who we see as the key players that maximise the benefits available through BIM. It is interesting to note how the two have approached BIM from opposite angles; Leandlease look to standardisation from the outset, while Laing’s approach is founded in speed of construction through DfMA. It is a credit to both how engaged they are in reaping the full benefits of the new BIM solutions available to the market.
Integrated functionality in BIM systems could mean the end for 2D manual quantity takeoff, as BIM allows for takeoff and estimating directly from the 3D model. The industry doesn’t use the BIM Material Takeoff capability to its full potential. This is a shame as it provides an earlier understanding of cost, as well as easier and quicker tracking throughout the process.
If utilised correctly, contractors will be able to cost more accurately and therefore protect their profits. The problem with Material Takeoff can often be down to scope and LOD. Most designers will sign up to a scope of LOD300. This is a fair LOD for the design and detailing of projects. Regardless of the LOD, Quantity Surveyors can still benefit from BIM at whichever level of detail the model has been taken to, so long as they understand the gaps/risks. For example, regardless of the LOD, designers will go through a takeoff process to provide a schedule of doors. This is a takeoff from the model, as door schedules are no longer manually inputted into schedules. Therefore, 2D information provided by designers to Quantity Surveyors is a material takeoff and will allow for early evaluation of cost. Designers are already working in this way.
Designers will provide models with caveats against the reliability of material takeoff, and it is correct to do so; however it should be seen as an aid, not an absolute. If Quantity Surveyors respect the limitations but also understand the opportunities, then quantity takeoff from models can improve the accuracy and efficiency of costing. It can be run at earlier stages of the project and easily monitored throughout to highlight any red flags in the design.
As mentioned above, there are contractors who are engaging well with BIM for the purposes of takeoff by managing the input through a digital warehouse, where each item already has a cost associated. Designers can piece together these assemblies within a model and then take a count of how many within the project.
BIM models, although in 3D, do produce 2D drawings. But designers can’t be expected to turn every 3D junction into a 2D presentation. This is where BIM comes in to play. As experienced designers, BSBG will identify areas critical to the design intent and then produce a 2D representation from those elements. Typical details will then be used that can be applied to a variety of conditions. The expectations will then be on the contractor to apply these.
Although the detailing might be there to achieve the intent, it is helpful for the contractor to have access to a 3D model to understand further the application of the detail and how it must achieve the end product.
Within the UAE we are starting to see a new trend in architecture – large scale refurbishments. Refurbishments are challenging, and involve a new approach not often used here. But BSBG has welcomed the challenge to further test our digital capabilities and to embrace innovation and new techniques to accomplish the successful delivery of refurbishment projects with the highest level of complexity.
Existing refurbishments come with a significant risk on cost – cost for the designers, the contractors and the client. The older the building, the more risk it comes with. For contractors, the risks are higher on existing buildings as there will be a lot of unknowns which are often discovered during the process. Therefore, it is imperative to make the most of BIM technology to fully understand the existing building as early as possible.
BSBG has had a fantastic experience on a very interesting existing building in Dubai through the implementation of 3D RCS & RCP Point Cloud and LiDAR survey input. We have worked alongside Urban Surveys, who completed a laser survey, which then allowed us to build an extremely accurate 3D Revit model before the end of the concept stage. This has resulted in an early-stage understanding of the cost implications in relation to the existing building.
When a contractor is appointed they will reap the benefits from quickly understanding the remedial works required, risk associated with existing services/structure at the outset, without having to visit site. Logistics will be far easier to plan with such an accurate existing model to review. We will shortly publish an in-depth case study on our experience of LiDAR and 3D Surveying.
Pre-fabrication is a very exciting topic within the market at present. As mentioned above there are some contractors that really are pioneering the approach to pre-fabrication from BIM. The value that pre-fabrication brings to the table is second to none. It provides:
It’s interesting to see the different approaches adopted by contractors. Some are approaching from the outset by providing more design/model guidelines/limitations, while others manage the input strictly with a catalogue of elements already tried and tested. There is significant synergy to be found in connecting these two dots. When these dots are fully connected, the industry will reach the next level of BIM integrated solutions.
The site logistics phasing facilities available within BIM are one of the best tools for contractors to understand how they should approach construction. BIM software has the ability to create detailed 4D sequences for all activities before the project goes on site, making for a comprehensive and coordinated construction process. BIM is the most widely used digital construction technology among contractors for site planning and virtual logistics because, quite simply, all information relating to the construction process can be collected and leveraged to plan and execute a project in the best, most efficient way.
Conventional methods for scheduling and site logistics don’t often bring clarity as to the reasoning for sequence of activity. Using BIM ensures everyone understands the nature of planned activities, and when they will happen.
It should also be noted that construction sites are dangerous places, where logistics can be the difference between life and death. As mentioned, BIM can simulate all activities on site, including the path of a delivery truck traffic through the site. This creates awareness of where there will be significant hazards during the construction stage and allows the contractor to move on site with action plans in place to protect all.
BIM has the potential to provide data on life expectancy and replacement costs of materials and systems. This data can be utilised to provide a clear picture to the project owners in gaining perspective when it comes to investing more in higher quality products to save cost in the long run. Lifecycle data is important too in the forecast of costs related to upgrades and improvements on systems in the future.
When projects are complete, there are further opportunities to integrate BIM software into facility management software. Often on large scale projects contractors will remain as the acting FM for the project, and therefore having BIM models to easily and quickly understand how the building has come together is invaluable. If there were to be future developments on the same project, they should run much smoother than the first. Providing the contractor appoints competent consultants to contribute the best quality models, something BSBG prides itself in providing. If the model is not to the quality required, it can actually hinder the next extension/refurbishment.
You can read more of Mark’s BIM articles by clicking on the following links: