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Re: Trees adjacent to retaining walls.

Re: Trees adjacent to retaining walls.
Posted by: chris (IP Logged)
Date: October 08, 2007 14:09

Well I think if I worked for a "global design and business consulting firm" I'd probably be wanting to pay for such advice from someone whose credentials and professional indemnity insurance I was able to check, rather than asking on an internet forum :)

The situation is not the same as for foundations. Foundations are geneally only damaged by the indirect action of roots drying out soils that shrink.

Retaining walls, by contrast, can be pushed out by the direct action of roots or the trunk thickening, or by them knocking continually against the wall as the tree moves in the wind. The forces are not great, and new, well engineered structures are less at risk than older structures. BS5837:2005 gives the following suggested clearances from boundary walls, the first figure being where minor damage is acceptable, the second (in brackets) where no damage is acceptable:

30 - 60cm diameter at maturity: 0.5m (1.0m)
> 60cm diamater at maturity: 1.0m (2.0m)

This is merely guidance, and a site specific assessment should really be made.

Subject Posted By Posted
|  Trees adjacent to retaining walls. Robert Innes 08/10/2007 10:11
||  Re: Trees adjacent to retaining walls. chris 08/10/2007 14:09

Advice offered in this forum is of a general nature only. It is by its nature not based on any site investigation and should not be relied upon. Neither the forum administrator nor any contributor will be held liable for damages occurring as a result of relying on advice given here. You should contact a competent arboriculturist for a more detailed answer.