Specialist Architectural Services
The Spec Man Blog - topical comment from a freelance specification writer
Who specifies What?
Posted: 13 February 2012 : Link
One of the questions that I'm constantly asking architect-clients is "Who is responsible for specifying ........ (insert item, usually structural)?", to be met with a mumbled "Well ........ I'm not sure". This might be understandable if the architect is inexperienced, but it's becoming increasingly common at all levels. The question really is fundamental, and goes straight to the key issue of liability, so it's surprising that teams will launch-off into production information without giving it a minutes thought - until I ask the awkward question of course.
Large practices, and many well-organised client companies, have some form of Responsibilities Matrix which sets out exactly who is to be responsible for designing-and-specifying what, but some of these matrices will not be sufficiently comprehensive to cover all the potentially contentious items listed below.
Irrespective of who-is-specifying-what, I believe that it is crucial to avoid split responsibility within the specification. Most NBS work sections are very easy to assign to a single construction profession but, in my experience, there are three main areas where omission or conflict with the Structural Engineer (SE) can occur. Use the list below to check who-is-specifying-what, and take the appropriate action.
Underslab elements
- Underslab waterproofing membranes : Use J40 if specified by the Architect. Not normally necessary for the Architect to cross-refer if specified by the SE.
- Underslab insulation : Use E20 if specified by the SE. Use P10 if specified by the Architect (this allows the Engineer to take 100% responsibility for E20 if they are using NBS). Not normally necessary for the Architect to cross-refer if specified by the SE.
Brickwork reinforcing, support, and fixing accessories
- Ties, windposts, supports, reinforcement : Use F30 (clauses 210 to 291) if specified by the Architect. If specified by the SE, cross-refer from the Architect's specification: keep clause title; delete NBS clause content; add "Refer to Structural Engineer's specification". This is necessary because the SE is unlikely to be specifying all the items in F30/210 to 291 and completely omitting SE-specified items can cause confusion.
- Lintels (proprietary to BS EN 845-2) : Use F30 (clauses 735 to 755) if specified by the Architect. Not normally necessary for the Architect to cross-refer if specified by the SE.
- Lintels (non-proprietary) : Use F31 if specified by the SE. Take project-specific action, following the general principles above, if the SE is responsible for the lintels but the Architect is responsible for the sills, copings, and other features.
Structural timberwork
- Structural carpentry and timber framing : Use G20 if specified by the Architect or the SE. Take project-specific action if the SE is responsible for some elements and the Architect is responsible for others - there are no general 'rules'.
- Sheathing to timber framing : Use G20 if specified by the SE. Use K11 if specified by the Architect (assuming that it is non-structural). Not normally necessary for the Architect to cross-refer if specified by the SE.
All the above advice is based on the use of NBS Building. It may (and the codes certainly will) all change in NBS Create.
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