Hi Cullenloon,
We have spoken before you may recall as I, though not a Cullenloon myself, am proud to be the product of a long line of Cullenloons.
Moving on....
The term 'large and complex' is only used in these documents in a general way and there are no precise recommendations that should be followed if a building falls under this description and that need not be followed if a building does not fall under this description. Therefore, I wouldn't worry too much about the exact meaning as none is given.
The only recommendation that falls roughly in line with the category boundary that separates 'large and complex' buildings from more run-of-the-mill buildings is the recommendation in 7974 for when a QDR team might be needed. But the need for a QDR team is something that grows proportionately with the complexity of the design and the precise level of complexity at which a QDR team becomes necessary is a matter of perception and judgement, not a matter of trying to make the building fit into one category or another.
I think kurnal's right when he refers to context. Look at what the documents are saying when they use this term. I believe that what they are trying to say is that where a building has some characteristics that make it difficult to comply with standard fire safety guidance, whether because of its complexity or its sheer size, then fire engineering solutions may be more appropriate than normal code compliance. Perhaps the term should have been 'very large or complex'.
Stu
