Trees are an important environmental asset, however the council recognises that in some instances they may contribute to the subsidence of a building.
Where an application is made to fell a protected tree (one subject to a Tree Preservation Order (TPO) or located in a Conservation Area), due to concerns about alleged subsidence, it is important that adequate information is included to demonstrate that:
- the subsidence has actually taken place
- investigation has been undertaken to show the effect of the tree
- reasonable alternatives to felling have been considered
Application documents where subsidence is alleged
The following information should be included:
- engineers report on assessment of damage to building
- plan and profile of foundations
- full details of all areas of damage attributed to the subsidence including location plan of building in relation to trees both on and adjacent to the property
- soil analysis – including proof of desiccation, details of liquid and plastic limits taken from both a trial pit and control pit
- tree root identification & analysis from beneath foundation level
- monitoring results preferably for 6 months or more, including level monitoring
- details of any drainage report carried out for the property
- details of previous underpinning or relevant building works to the property
- the range of alternatives considered and estimated costs, including a comparison between scenarios in which the tree is retained or felled)
In some cases officers may ask for further information such as:
- details of vegetation in the vicinity and its management since discovery of the damage
- a plan showing the vegetation and affected building
- the location and identification of roots found - where identification is inconclusive, DNA testing should be carried out
For private individuals who have concerns regarding alleged subsidence and TPO trees, please email treeofficer@havant.gov.uk