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iTWO costX® Consultant Series: Key Discussion Points for 5D BIM

For our latest blog post, RIB’s London-based EMEA Lead Consultant Matthew Donnison has covered some helpful considerations for QS/Estimators involved on a 5D BIM project for the first time.

Using BIM for quantification purposes (otherwise known as 5D BIM) can be a daunting task for the first time, and all too frequently the QS/Estimators aren’t part of key discussions regarding the model.

At RIB, our Consultancy team has guided hundreds of organisations through the process, and there are a number of repeating themes that we encounter. I will explore some of these considerations below, to provide key discussion points for first-time users with their respective design teams.

All too often, the QS/Estimator is a mere afterthought in the discussions surrounding the design process. However, by having a good general understanding of the process and associated benefits and drawbacks, appropriate advice can be given to both the Client and design team. This can help to provide focus on areas of maximum benefit in line with the overall procurement objectives.

These points should be covered as part of the Employer Information Requirements (EIR) and BIM Execution Plan (BEP), so you must review and challenge these documents appropriately as the project’s QS/Estimator.

Basics

What will the model be used for?
This might sound simple enough on the face of it, but is really the key driver that will inform everything else – is it just a design tool, is it for clash detection/coordination purposes, cost estimation, facilities management, etc.?

Will all disciplines be involved?
How are the Architectural, Structural and Mechanical & Electrical teams planning to work? Will they all be utilising BIM or will some be providing 2D designs? Will you use a different model for each discipline or will you use a federated model (as this will impact on your iTWO costX® workflow)?

How will revisions be handled?
There can be many thousands of revisions to the model during the design phases – how frequently will the quantification and costings be updated? Fortunately, iTWO costX® makes it easy to track change in quantity and cost through the revisioning functionality, however controls still need to be put in place.

What file formats will be utilised?
iTWO costX® can open models in DWFx, RVT, CPIXML and IFC formats (among others). There are pros and cons to each option impacting upon computer hardware requirements, data completeness, proprietary vs open standards, etc.

How will the models be transmitted?
Linked to the point regarding revisions, how will the files be transmitted/stored? This particularly relates to when comparisons need to be carried out on the model to understand any cost changes.

What content will be modelled vs 2D detailed?
Frequently, not all aspects of a design will be modelled, and can just be manually drawn as detailing onto the 2D drawing outputs; for example, skirting boards within a building. The extent of this needs to be agreed beforehand and everyone made aware so that the QS/Estimator can make appropriate allowances for it.

Naming conventions – minimal vs descriptive?
Rather than an object in the model being called something like “Wall-CavInsBlkBrick”, it can be useful for the names to be fully descriptive and more widely understood. These descriptions may also change over time between concept and detailed design phases, so the process for updating model content needs to be understood by all.

Contractual standing of the model?
What is the contractual status of the model versus the 2D drawings? Can this be influenced at all?

Quantification

What coding is going to be applied to the model?
The model is frequently coded with Uniclass data, whereas the QS may be preparing an NRM1 cost plan or an NRM2 bill of quantities, and there isn’t a complete (public) mapping between these coding systems.

Project Units – what rounding will be applied?
If every object is exported to zero decimal places for the quantity information, this can lead to discrepancies on large projects. Ensure this is set appropriately for your requirements.

Parts vs Assemblies?
Rather than having a single object of a composite slab exported, it can be useful to have the individual components exported and quantified (e.g. blinding, concrete, rebar, screed etc).

Areas/Rooms
When creating Area Schedules, it can be extremely useful to have the Area or Room data available from the model.

Deliverables
How will the resulting cost plan, estimate or Bill of Quantities be shared with the Client or other Stakeholders? As well as a traditional output, the free iTWO costX® viewer can be utilised to enable a live-link between the quantities in the deliverable and the model.

Quality Assurance
How will checks be carried out at various stages of the process? For example, the model needs to be checked upon first receipt, and the final deliverable needs to be cross- referenced against the model or drawings (depending on the contract).

Wider Impacts on the Business

How will success be measured?
Will the time taken for both the initial takeoff and future revisions be tracked and compared to other more manual workflows? What are the ambitions for quantification from the model versus 2D drawings – and is this calculated by item or by value?

How is the learning curve allowed for?
The first time that teams undertake any new process there will inevitably be a learning curve, and this needs to be planned and allowed for to prevent staff just giving up and going back to the “old way”. Will there be a senior sponsor within the organisation to support, promote and monitor progress?

How will this impact future work winning?
How will this information be fed back to business development teams to be utilised in fee proposals, and how will fee proposals be written in future to specify minimum requirements for models?

How will you enable knowledge sharing?
The lessons learnt on the initial 5D flagship projects need to be recorded and shared amongst the wider team to ensure continued success.

Digital Sample Board

Rather than waiting for weeks or months for the model to be delivered, followed by a short period to carry out checking and quantification, discussions can be conducted alongside the design process.

I like to use the concept of a Digital Sample Board, whereby the design team provides the QS/Estimator with samples of the content they are using.

In iTWO costX®, it doesn’t matter if you have 1m of a pipe object or 1,000,000m of the pipe object – getting a sample enables you to check it in line with your proposed workflows, and substantially complete any custom iTWO costX® Model Maps required for project-specific breakdowns.

If you’ve completed all the preparation work from the Digital Sample Board, once the final model is delivered it should then be a very quick process to extract the quantities in exactly the way you require.

At RIB we have many resources and training options to guide our customers through this process, and we have a highly qualified international team of Consultants able to provide assistance.

If you have any enquiries about the 5D BIM functionality and potential of iTWO costX®, don’t hesitate to reach out to your local RIB office today!