P.G. Biddle

Institution of Structural Engineers Report.

Second Edition. August 2000

The second Edition of the Institution of Structural Engineers' Report on "Subsidence of low-rise buildings" provides a major revision of the report that was originally published in 1994, particularly in the inclusion of a new Chapter 8 on ‘Trees and Tree Management’.

Giles Biddle was one of three arboriculturists (together with David Cutler of R.B.G. Kew and Jim Smith of LTOA) who were invited onto the Task Group to assist in the revision and to draft the new Chapter 8. In 8 pages, most of which are pictures, this chapter can only provide very superficial coverage, but at least it gives balanced guidance on the role of trees, and the requirements for tree management. I draw attention to two aspects in particular:

  i) level monitoring should be the preferred option for determining the efficacy of any remedial action with trees, and should commence prior to any action on the trees.

  ii) Section 8.6 on Tree management for the prevention of subsidence damage, which states:

In addition to contributing to the drafting of Chapter 8, Giles Biddle was invited to chair the sub-group drafting the revisions to Chapters 5, 6, and 7, and personally undertook the extensive revisions to Chapter 7 on "Further Investigations". Throughout the report a number of the diagrams from Tree Root Damage to Buildings are included, although it should be noted that Figure 8.4 is an incorrect representation of Figure 3.3, and that the scale of the pictures in Figure 8.5 has not been adjusted to show the extent of crown reduction.

The report includes references to other publications, but it is gratifying to note that Tree Root Damage to Buildings is one of only two publications given special mention as Bibliography.

"There are no sound economic grounds for widespread and indiscriminate pruning of trees in case their growth could lead to subsidence in the future. The cost of such work would far outweigh the cost of remedial treament in those instances when direct connection between subsidence damage and trees has been established. Individual circumstances are paramount, and the possible interaction of each tree and building should be considered on its own merits, as part of the general care of the tree."