Welcome to our online course – BIM Basics for Quantity Surveyors and Cost Estimators. The course is centered around the understanding of key aspects of BIM so you can take full advantage of this methodology in your own workflows. The content is split into three sessions that will be recorded and you will be able to watch them on demand. Everyone that enrolls in this course will receive a test at the end to get a BIM basics certificate from Bimmetry and Glodon Singapore.
1st Session – BIM modelling for QS
2nd Session – BIM management for 5D BIM
3rd Session – Take advantage of BIM on your next QS/ cost estimation project
The course is organized by Bimmetry and Glodon Singapore.
Recording – Session 1 – BIM Modelling for QS
Session 1 Content:
Contactors often do scan to BIM, which is a 3D scanning of a site or a building to produce accurate as-built drawings or to study existing site or construction. Developers on the other hand might want to use the BIM models for space management and tender management. There are a few tools that are specialized for the developer’s portfolio asset management, which are different to the FM tools. But let`s see now how the BIM models are useful for the consultants. Design consultants use BIM to produce 2D documentation and 3D visualizations. You can use the BIM models to make AR and VR walkthrough the models. As we live in three dimensional space, the 3D representation helps us a lot to visualize the design before building it. It also helps us to make clash detection. Here is the moment to mention that as we have multiple consultants on a construction project, so we have multiple models. We usually have architectural firm producing the architectural model, structural engineer modelling the structure, MEP consultants doing the services models. All these models get linked into a single file and by visual digital inspection of the models, we can easily see any clashes that are happening. We can also run automated clash detection and run regular design meetings and report the status of the clashes.
We already mentioned that you could get involved in animated construction simulation including the cost – 5D sequencing. You can also get the models, extract the quantities, and speed up your work greatly. For example, Cubicost can help you do that. All you need to do is insert the Revit model into Cubicost and you have all the quantities structured and you can further add cost to it. The great thing about Cubicost is that it will not only extract the quantities, but it will make automated deductions, which the BIM authoring tools don`t always do. So, if you have a window for example, the volume will be automatically deducted from the wall mass. Cubicost will also automatically generate the quantities for your structural components’ reinforcement and formwork. You basically need 1 minute to import the model and 50% of your cost estimation job is done.
Often people don`t make a difference between a 3D modelling software and BIM authoring tool. For example, BIM authoring tool is Revit, Archicad and Vectorworks. They produce 3D geometry, but every object is recognized by the program as a different CATEGORY with certain properties. For example, a column is a structural component, it has material, profile, cost and so on. The 3D modelling software as Sketch Up and Rhino also generate 3D geometry, but it doesn`t have the meta-data that the BIM models usually have. There are plug-ins and workarounds to turn 3D geometry to BIM model, but essentially this is the major difference. Revit produces 3D geometry and meta data information, while 3D studio max usually is used when we only need 3D representation without the additional information. This is good to be remembered as if you hear that certain model was created in Rhino, then you might not have the data you need from this model, you can reference the 3D geometry, but you might not be able to extract the quantities that you would usually be able to extract from Revit.
As we saw in the Revit interface video, often we have 2D lines instead of actual 3D objects, but it still looks ok for the drawings, the problem comes in the scheduling, you won`t get the quantities for objects that are drawn with 2D lines only. There might be some naming/ type mistakes in the model. Let`s say two identical types of windows might be named differently. You might also have duplicating geometries. Cubicost might help you fix this, but it is a common issue in BIM modelling.
There are some general recommendations to be followed
As the objects to be modelled in the right categories. And stairs to be modelled separate from the railings to get them scheduled correctly in Cubicost. Ramps to be modelled as ramps instead of sloped mass for example and set the structural components as structural.
Well, one thing is in case you are involved early in the design process to mention that the BIM models will be used for QS. And set some requirements to be included in the BIM execution plan, for which we will talk in the next session.
You can of course also review the models. You can open them in Revit directly or in Cubicost, which is way easier for QS professionals to learn and see where you might have some inaccuracies. This kind of issues happen often, but on the other hand they are a very small percentage of the modelled geometry, so it is still worth to take the models and get the most of them.
To get a general quick check you can choose a portion of the building take some estimates automatically and manually and see if the results are similar, this will quickly point you to some conclusion about the quality of the BIM model.
On most projects, we have a BIM Lead/ BIM manager who can be on the client-side, construction side, or consultant side depending on the contract. Usually, this is the person responsible for the BIM execution plan, who defines the future use of the models. If you have special requirements for the models, this is the person to talk to. Also, most consultants have their own BIM office leaders and project dedicated BIM project managers and coordinators. The document controller is the one to make sure the BIM models and documentation is correctly uploaded on platforms such as Aconex or Procore.