Roger Lever, md of Excel Industries, is proprietorial about the term 'breathing wall' (aj 5.11.98), which is understandable since Excel has promoted its recycled newsprint insulation product using the term.
However, it is not as far as I am aware a trade name, nor is it otherwise protected in law, nor is the term the exclusive property of any individual or organisation. It is in common use or abuse, as the case may be, and in fact has a long history, being first coined by Dr M Marker and Professor Max Von Pettenkoffer in 1870 to describe the flow of air and moisture through masonry walls, lime mortar and compacted gravel.
Despite this, if Mr Lever wishes to have the term 'breathing wall' associated with a particular form of timber construction using a particular insulant which Mr Lever's company manufactures, then why not? As he himself points out: 'walls do not 'breathe' in the true sense of the word', so the term is scientifically meaningless in the context anyway.
And this is the crux: if architects and others are to understand the performance characteristics of timber-frame walls (or any other building envelope), as Geoffrey Pitts (aj 15.10.98) quite rightly suggests, then accurate and unambiguous terminology is essential. Better by far that the inaccurate term 'breathing wall' be confined to one well- defined, proprietary method than to burden the whole building industry with the careless use of that term. Come along, Geoffrey Pitts, who needs such second-hand and misapplied terminology? Be bold, and let's have some scientifically accurate and easy-to-use new terms which meaningfully describe the transport of water vapour through building envelopes.
DR DOUGLAS CAWTHORNE