Friday, 25 May 2012

The Importance of Specification

One blog post that is definitely worth a read is the guest post on specification by Adrian Williamson The NBS: the Woes of a Specifier on Su Butcher's blog - it's a warts-and-all view on using NBS Building.

Adrian Williamson
One issue discussed by Adrian was:
" you write or edit individual sections clauses as you are producing the working drawings or complete the spec once you’ve have a full set of complete drawings and then cross reference them against the NBS? I’ll let you decide on what’s the preferred route; we opted for the latter."

At NBS, we do offer some assistance here. At the most basic level, you can export your clauses to "annotation" database. You will get a little exported database with the clause references and titles from your project spec or office master. These will slot into the AutoCAD or Microstation or Vectorworks CAD system and allow you to simply pick from them to annotate your sections and elevations.

So if you are annotating a window, you can quickly pick from your list of clauses. For example picking a reference such as "L10/350A PVC-U Windows Type A" or "L10/350B PVC-U Windows Type B"?

However, with the growth of Building Information Modelling (BIM), the task of putting together a coordinated set of drawings has became even easier. It is a far more robust process. At NBS, we currently have BIM plug-in tools for Graphisoft ArchiCAD and will soon be releasing one for Autodesk Revit. We also are in discussions with Vectorworks, Tekla and Bentley about integrating within their systems. In the example below I have attempted to demonstrate the benefits of the linked data models using a basic example.

Consider a design-and-build job where an architect is putting a performance specification for the client (what maybe could be considered a COBie drop 2A). If we look at a simple internal partition system, it is likely that the architect will not specify the individual products. It is likely that architect will not specify the workmanship. But they will specify the system's overall performance. The screen-shots below shows a typical project specification and the associated guidance. Key metrics such as structural, acoustic and fire performance are specified, whilst leaving the design of the system to the lead-contractor. In addition to these performance requirements, the testing requirements and submittals to verify the performance are specified.
Fig 1 - Specifying the performance of an internal partition system
Fig 2 - Pages and pages of detailed guidance and reference documents supporting the specifier
And now it's a simple job for the architect to link the "object" in the central BIM representing the partition with the "object" in the specification model also representing the same partition. The clever plug-in looks directly into the specification and allows the user to easily pick out the correct clause.
Fig 3 - Using the NBS plug-in to link objects in central BIM and specification model
Where this process has particular robustness is the ability to check that all annotations are correct prior to issuing any drawings and specifications from the complete BIM.
Fig 4 - Using the NBS plug-in to report on any coordination issues between drawings and specification
Now I could not have picked a more simple example above - imagine the performance requirements of an air conditioning system or of a complex curtain wall system. Being able to specify this in a tool like NBS Create and then link the spec to the drawings/BIM is crucial. Also, consider a fully specified system with all of the products specified (DPC, frame, plasterboard, fasteners, finish, cavity fire barriers...) and the plug-in becomes even more useful. Click the picture below to see each object in a full specification (not just performance) to see the scope of content for just a simple system:
Fig 5 - A fully designed system in NBS Create
So hopefully this article demonstrates how the links between drawn information and detailed specification information is really improving. Finally, going back to the original post that prompted this blog post, I think that Andrew Brown's summary of thoughts making the case for a well-written, robust, specification is probably the best I have ever read:

Andrew Brown
"...there really is no alternative to allowing adequate time to write the specification whatever system is used. The specification is an essential document in communicating the design intent to the contractor and should not be considered as a painful-but-necessary add-on to the drawings. As I’ve been saying for many years … when did you last hear someone say 'Are we covered on the drawings?' when something goes wrong, it’s always 'Are we covered in the specification?'. There are many times when a picture is not worth a thousand words, but a handful of carefully chosen words are worth several thousand megabytes of drawings."
Andrew Brown - 35 years experience with the likes of BDP and Sheppard Robson

1 comment:

  1. Hi Stephen,
    Thanks so much for posting this and linking back to Adrian's post.
    An excellent example of practical blogging technique!