What is a tree survey?
A tree survey is an inspection of the tree stock located within the boundaries of land/ property. This includes woodlands, parks, private property, building developments etc. A tree surveyor will record various data such as tree species, tree location, life stage, condition, work recommendations if required and timescales any work will need to be completed within.
Are there different types of tree surveys?
Different types of tree survey include:
– Health & safety tree survey/ tree hazard report
– BS5837 tree survey and arboricultural impact assessments (AIA)
– Subsidence report
– PiCUS testing
What is a health & safety tree survey?
Health & safety tree surveys are generally used by landowners, schools, private home owners, housing associations etc. for general insurance purposes as well as supporting any works that may be required within conservations areas and work on protected trees/ trees served with a tree preservation order (TPO).
When a qualified tree surveyor carries out a health & safety tree survey, the main factors they will record are as follows:
– The tree will be allocated its own tree number/ ID for the survey if it hasn’t already got one (E.g. T1 for an individual tree, G1 for a group of trees)
– The species of the tree (s)
– The life stage of the tree, recorded either as young, semi-mature, early mature, mature, veteran) – A brief description of the tree, including any nearby targets and other survey notes of the trees condition.
– Measurements of the tree such as its height, DBH and crown spread.
– Structural and physiological conditions
– Amenity value
– Wildlife value (habitat etc.)
– Any inspection limitations
– Recommendations for any works that will be required to the tree as well as timescales they should be completed in.
As well as recording the above information, a surveyor will also complete a tree condition report, which will usually include the soil type, local authority details, a tree location plan, and a general overview of the site.
What is a BS5837 survey?
When submitting any planning applications, usually a BS5837 survey will be required for any trees that are located on the site alongside the planning proposals. With a BS5837:2012 survey, this will be made up of the tree survey, tree constraints plan and arboricultural impact assessment. Within the survey, trees will be assessed and given a retention category. These specify by Cat A, Cat B, Cat C and Cat U.
When submitting a planning application, usually a BS5837 survey will be required for any trees that are located on the site alongside the planning proposals. With a BS5837:2012 survey, this will be made up of the tree survey, tree constraints plan and arboricultural impact assessment. Within the survey, trees will be assessed and given a retention category. These specify by Cat A, Cat B, Cat C and Cat U.
Cat B trees are usually trees that have at least a remaining contribution of 20 years and will be of similar quality to Cat A trees, but potentially with less amenity value or historical features. Like Cat A trees, Local Planning Authorities also like Cat B trees to be retained where possible.
Cat C trees are usually that of poor quality with a remaining contribution of approximately 10 years. Unless within the planning proposals it is proposed for a large number of Cat C trees to be removed, the loss of a Cat C tree is usually considered and the Local Planning Authority can request for replacement planting.
Cat U trees are trees that are considered as dead, dying or as dangerous with a remaining contribution of 10 years or less. These trees don’t usually have any constraints and are usually advised to be removed.
Any trees to be retained (either Cat A or Cat B trees) are to then be protected throughout all stages of building works, which is where the root protection areas (RPAs) come into place. In order to work out an approximate radius of the area to protect the roots, the surveyor will measure the diameter from 1.5m of the main stem above ground level, then multiply it by 12. In order to protect the canopy and roots from building works, heras fencing will often be installed.
As well AIAs (arboricultural impact assessments), the surveyor carrying out the BS5837 survey will also create tree constraints plans which will usually be created using AutoCAD to allow for architects to be able to overlay the mapping with their designs for planning proposals.
What is a subsidence report?
A subsidence report has similarities to a health & safety tree report, however, this form of report also looks into any structural damage/ subsidence that might have been / has been caused to property due to growth of tree roots. Properties that have been constructed on clay soils within close proximity to trees may encounter subsidence due to soil shrinkage as moisture is extracted
by tree roots.
This type of report is usually required by insurance companies and sometimes mortgage lenders.
Subsidence reports tend to include the following factors;
- Soil analysis
- Root identification
- Movement monitoring
As well as the factors that are included for health &
safety tree surveys.
What is PiCUS testing:
PiCUS testing (sonic tomography) is used to determine the extent of decay in a tree caused by internal decay, cavities and fungi such as Ganoderma sp. A PiCUS test is carried out by sending soundwaves through the stem of the tree (usually carried out anywhere from base to approx. 2m in height). The extent of decay with the stem of the tree is then determined by how quickly the sound
travels through the wood.
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