Subsidence News and Updates:
BRE Digest 298
April 1999

.... Level monitoring surveyors.... ABI Report .... Deep datum.... Staffs for level monitoring....
New Research Project.... Tree Preservation Orders.... Court of Appeal .... Case Study 6....
BRE Digest 298.... ISE report .... Corrections.... HortLink Project ... P.G. Biddle O.B.E....


An extensively revised edition of this Digest was published in April 1999. Whilst most of the text of this Digest is a considerable improvement, it is disappointing that it continues to advocate that the choice of remedial action should depend on the relative ages of the tree and building.  As noted in Chapter 16 of Tree Root Damage to Buildings [p261], it is relevant to consider when the persistent deficit developed, and relate this, rather than the age of the tree, to the age of the building.  Just because a tree is older than a building, it does not mean that there will be a risk of heave.  Conversely, even if the tree is younger than a building, if it has managed to produce a significant persistent deficit, there can be long term recovery movements if it is felled.  For this reason, diagnosis should seek to determine when the persistent deficit developed and relate this, rather than the age of the tree, to the construction of the building.  

BRE Digests are often considered to be the definitive statement on a subject.  Readers might therefore be interested in the following extract of a letter from Mike Crilly of BRE with reference to my comments on Digest 298:- "The Digest is intended to provide simple guidance, primarily aimed at non-specialists; it is not meant to be a comprehensive treatment of the subject. I would agree that the existence (and, as importantly, the magnitude) of a persistent water deficit is more important than the relative ages of a tree and property".



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