Framing the Standard Task List (STL) in the Bouwdata© methodology

Bouwdata

Dec 5, 2024

Framing the Standard Task List (STL) in the Bouwdata© methodology

In August ’22, the Standard Task List (STL) was published on BIMPORTAL. It came about in a collaboration between Buildwise, the G30, ORI and VBA-ADEB. The source of inspiration was the DNR in the Netherlands, which has its roots in table 1 of NEN 2699 “Investment and operating costs of property – Terminology and classification”. A standard I have been dwelling with since it came out … except for that one table!
Below, I explain why but also how, in terms of cost control, we can “knit everything together”.

Table 1 of NEN2699 – “Level of expandable table linked to stages of the construction process” is still based on the design-bid-build construction paradigm by creating a stage 7 Pricing/Contracting with an associated tender budget. This involves pitting the design group, via usually a tender purely on price, against the execution team. A business culture that has since long proved its bankruptcy. A business culture also which, on the other side of the channel, has already found a solution since 2013 i.e. RIBA plan of work.

So what is the big difference between the British and the Dutch?

RIBA plan of work considers the hiring of a contractor(s) in the process in the same way as everything else that needs to be procured to realise the building and therefore does not erect a “Berlin wall “. Procurement, like contracting a contractor, is a task that runs across all Stages .

In 2008, PB calc & consult received grants from the IWT (now VLAIO) to conduct prenormative research and develop an calculation system for the construction sector, called BouwData©1. This work has been “on going” since then and is also being systematically tested in practice.

The task now is to “knit together” the STL and this research .

0.0.0.0.000 START

At RIBA plan of work, this is Stage 0 Strategic Definition and is formulated as follows: “Stage 0 is not about design or the practical details. It focuses on making the right strategic decisions and capturing them in a Business Case.

In NEN2699, this stage is Stage 1 Initiative/Feasibility and we refer to it as an initiative budget at level 1 (headings) or level 2 (clusters).

The STL has only 1 task in this stage, namely making the list project specific.

Within the BouwData© methodology, this means making choices regarding:

  • Common Data Environment
  • How one wishes to involve the project partners in the whole process? 

1.0.0.0.000 FEASABILITY STUDY

In RIBA plan of work, this is Stage 1 Preparation & Briefing and is worded as follows: “Stage 1 is about developing the detail of the brief and making sure that everything needed for the design process is in place before Stage 2. This includes ensuring that the brief can be accommodated on the site.

In other words, the end goal of this stage, is to decide what is to be built or renovated on which site within which budget and timeframe.

In NEN2699, this stage is stage 2 project definition with a feasibility/budget definition at level 2 (clusters) or level 3 (element clusters).

1 The copyright is only there because the accompanying contract was an SME innovation project and therefore has copyright and a valorisation obligation attached to it. However, all research has always been made freely available to the public via the website www.bouwdata.net.

In the STL, task X1.0.1.3.001 deals with the price in each case.

In the further detailing under this step, the client, designer and builder are all involved. However, they are not precise enough, talk about budgets and estimates and do not say to which standard the surfaces should be measured.

Experience within the BouwData© methodology shows that level 2 of NEN2699 is “nice to know” but not detailed enough to objectively distinguish mass study A from mass study B. The Agentschap Facilitair Bedrijf has also realised this. That is why in spring 2022, together with BouwData and Bimplan, they wrote the white paper”Univocal framework for post calculation and 5D BIM” . During ‘project definition & briefing’, the parties involved are asked to provide an estimate based on element clusters in order to gain insight into the various architectural proposals. Since early 2023, GO! has also been following this insight.

We, BouwData People, therefore only talk about an estimate in this step – whoever prepares it – and measure the surfaces according to NBN EN 15221-6 supplemented by additional definitions to make things work in practice as well.

2.0.0.0.000 PRELIMINARY DESIGN

In RIBA plan of work, this is Stage 2 Concept Design and is formulated as follows: “Stage 2 is about getting the design concept right and making sure that the look and feel of the building is proceeding in line with the client’s vison, brief and budget. The key challenge of this stage is to make sure that the tasks that are undertaken are geared to meeting the stage objectives. Going into too much detail too early can pivot the design team’s effort away from setting the best strategy for the project; but if there is too little detail, Stage 3 becomes inefficient.

In other words, in this stage the framework for the supporting structure is established, as well as the location of the large circulation cores and technical shafts !

In NEN2699, this is stage 3 structural design with a structure budget (SO) at level 3 (element clusters) or level 4 (elements).

The word “preliminary design” in the STL is actually too non-committal and does not sufficiently encompass the objective of this stage. “Structural design” is more suitable.

In the STL, in this step the contractor makes an initial estimate of “construction costs at the level of main elements and based on unit prices per element and/or m2”. This is then checked by the architect and engineering firms. Only, again, no reference to a standard or classification making it difficult to compare estimation of main contractor A with estimation of main contractor B.

1 Number of the concerned stage

The BouwData© methodology always adopts the designation of RIBA plan of work, i.e. Concept Design and speaks of a budget made on the basis of elements.

It is important to note that at level 4 of NEN2699 the main structure of table 1 of the SfB is registered, but this is the old SfB. I.e. there should be an adaptation of the standard so that it fits their new 2019 version of the Nl-SfB.

In Belgium, the discussion on coding and description of elements is raging. Four possibilities were put forward in the sessions of Cluster BIM:

  • table 1 SfB
  • table EF elements/fonctions from Uniclass
  • tables Functional Systems/Technical Systems/Components from Cuneco Classification System
  • table 21 Elements from Omniclass.

Meanwhile, there seems to be agreement that they will go for Table 1 SfB, but not yet which edition.

BouwData People have opted for a mixture of the BB-SfB plus from 2008 for renovation and the NL-SfB for technical installations, supplemented with a number of further breakdowns to fit in with practice – see level 4 of the Object Code1.

3.0.0.0.000 DETAILED DESIGN

The STL seems to aim for obtaining an environmental permit at the end of this stage.

In NEN2699, this stage is 4 preliminary design with a preliminary design budget (VO) at level 4 (elements) or level 5 (which the standard itself leaves free)

In RIBA plan of work this is Stage 3 Spatial Coordination and is described as follows: “The purpose of Stage 3 is to spatially coordinate the design before the focus turns to preparing the detailed information required for manufacturing and constructing the building. The information at the end of this stage needs to be coordinated sufficiently to avoid all but the most minor of iterations at Stage 4 and to make sure that the planning application is based on the best possible information.

The BouwData© methodology always adopts the RIBA plan of work name, i.e. Spatial Coordination , and speaks of a budget made on the basis of components – see level 5 of the Object Code.

Like level 4 elements, this is a mixture of the BB-SfB plus from 2008 for renovation and the NL-SfB for technical installations, supplemented with a number of further breakdowns to fit in with practice.

The difference with level 4 is that there the discussion concerned the main structure of table 1 of the SfB while here the substantiation of each chapter is discussed.
1 i.e. one of the nine tables of the classification scheme available for free download at www.bouwdata.net

4.0.0.0.000 FINAL DESIGN

The STL seems to aim here for the selection of the contractor based on a classical, fully developed tender dossier .

It is working towards a final flat1 price with an emphasis on seeking optimisations. But again without any reference to standards or classifications.

In NEN2699, this breaks down into three stages:

  • stage 5 final design with a final design budget (DO) at level 4 (elements) or level 5 (which the standard itself leaves free)
  • stage 6 technical design/specification with a management budget at level 5 (which the standard itself leaves open) or level 6 (where the standard suggests switching to the STABU system)
  • stage 7 pricing/contracting with a tender budget. This can go from level 3 element clusters to level 6 (STABU)

In RIBA plan of work, this is Stage 4 Technical Design and is formulated as follows: “Stage 4 is about developing the information required to manufacture and construct the building. This requires information from the design team and the specialist subcontractors employed by the contractor, regardless of which procurement route is used.

As indicated several times above, the BouwData© methodology follows RIBA plan of work: procurement is atask” that runs through the entire life cycle of a building.
The executor can get on board…

  • …in stage 1 preparation & briefing in which the estimate based on element clusters…
  • …in stage 2 concept design in which the budget based on elements…
  • …in stage 3 spatial coordination in which the budget based on components…
  • …in stage 4 technical design in which the calculation based on a MLES1 calculation…

Is being agreed upon through a contract.

It is very important to note that in Technical Design the price is no longer determined on the basis of unit prices from previous projects, but on the basis of quotations requested specifically for the project on the market.

1 The question arises whether a fixed price is exclusive or inclusive of price revision? The builder will consider the latter to be self-evident while the designers and contractors will consider the former to be equally self-evident. So this needs to be very well specified when contracting !

1 Material, Labour, Equipment, Subcontracting

This step includes the entire virtual construction phase where the top down design logic is converted into bottom up execution logic.

In other words, the budget according to level 5 Components of the Object Code gets a Material Code next to it and is “re-sorted” into workresults (as per ISO 12006-2:2015).

A workresult includes a total price, a probable start date and end date and is therefore expressed in workable days.

For each executor, the workresults are plotted over time to produce a financial forecast that provides the benchmark for budget monitoring in the next step.

In the BouwData methodology, this ends step 4.

5.0.0.0.000 EXECUTION

In this chapter, the STL distinguishes the work preparation, construction phase and delivery (VO / DO).

In the NEN2699, this falls into two stages:

  • stage 8 execution-ready design with a construction/work budget at level 5 (which the standard itself leaves free) or level 6 (where the standard suggests switching to the STABU system)
  • stage 9 management with a control/monitoring budget at level 5 (which the standard itself leaves free) or level 6 (where the standard suggests switching to the STABU system)

In RIBA plan of work, this is Stage 5 Manufacturing & Construction and is worded as follows: “Stage 5 is when the building is manufactured and constructed.”

Within the BouwData© methodology, work preparation belongs to Stage 4 Technical Design.

In Stage 5 Manufacturing & Construction , BouwData People limit themselves to budget monitoring according to the principles of Earned Value Management with a rigorous follow-up of the changes and distribution of the associated costs among the various workresults (WR).

As long as a workresult has not been started, the contractor may make changes to the composition, start date and number of workable days of the workresult = updated financial forecast

Daily notes are made in the site diary on which work is being executed. A monthly progess report = ΣWR (#wd x €/wd). An agreed percentage of the number of workable days is only released when the Handover (cf. next step) of the work in question is completed.
If ultimately more days are worked than foreseen in the adjusted financial prognosis, it is important to register this and include it in the graph so that one keeps in touch with what is happening on site.

 

 

6.0.0.0.000

USE PHASE

The STL limits this phase to the transfer of instructions and maintenance programmes to the builder.

In NEN2699, this falls into two stages:

  • stage 10 aftercare – i.e. a step with no cost control
  • stage 11 use with an operating cost at level 5 (which the standard itself leaves free) or level 6 (where the standard suggests switching to the STABU system)

RIBA plan of work has a Stage 6 Handover and is worded as follows: “By Stage 6 the building will be in use and the emphasis of the project team will have switched to closing out any defects and completing the tasks required to conclude the Building Contract.”

Within the BouwData© methodology, this Stage 6 Handover is already started during the previous Stage 5. After all, as soon as a workresult is finalized on site, the following matters are immediately put in order :

  • Financial finalisation of the associated changes
  • On-site inspection and resolution of the Bad Work items or shifting them to the delivery list if there is still interaction with independent contractors.
  • Completion of the as built file for the works belonging to this workresult.

Only then does RIBA plan of work and therefore the BouwData© methodology move on to stage 7 In Use which is defined as follows: This is the period when the building is in use, lasting until the building reaches the end of its life.”

7.0.0.0.000

END OF LIFE This is a stage without further explanation

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