Tree Surveys & Risk Assessments

BS5837 Tree Surveys for Development Sites

If you are submitting a planning application for a site that contains trees or is adjacent to trees, the local planning authority will require a BS5837 tree survey. This is not optional — applications submitted without one are routinely sent back, delaying your project by weeks.

We produce fully compliant BS5837 reports that include every element your planning consultant needs: a detailed tree schedule, categorisation of every tree by quality and retention value, a tree constraints plan plotted to your site survey, and clear recommendations for tree protection during construction.

Our arboriculturists survey sites across Hertfordshire and North London, working with developers, architects, and planning consultants on projects ranging from single dwelling extensions to large residential and commercial developments. Recent BS5837 work has included a phased residential scheme in Borehamwood and an office redevelopment on a mature-treed plot in Welwyn Garden City.

Tree Condition Surveys

Not every survey is linked to a development proposal. Property managers, housing associations, local authorities, and estate managers need regular tree condition surveys to maintain their tree stock safely and demonstrate compliance with their duty of care.

Our condition surveys assess every tree in your portfolio for structural defects, disease, deadwood, and proximity to buildings and infrastructure. Each tree receives a priority rating so you can plan remedial works systematically and allocate budgets effectively. We run rolling condition programmes for a housing association with stock across Harpenden and Potters Bar, and survey mature avenue trees for a private school in Berkhamsted.

We can set up cyclical survey programmes so that your entire tree stock is reassessed at appropriate intervals — typically every 1, 2, or 3 years depending on the risk profile of each site.

Quantified Tree Risk Assessment (QTRA)

Where a more rigorous approach to risk is required, we use the Quantified Tree Risk Assessment methodology. QTRA moves beyond subjective judgements by assigning measurable values to the probability of failure, the target (people or property beneath the tree), and the consequence of impact.

The resulting risk figure can be compared directly against the HSE's broadly acceptable threshold of 1 in 1,000,000 per year. This gives you a defensible position if a claim is made, and helps you prioritise spending where the actual risk is highest rather than reacting to every concerned phone call.

QTRA is particularly valuable for local authorities, social landlords, and property companies managing large portfolios of trees in public spaces.

Arboricultural Impact Assessments

An arboricultural impact assessment (AIA) evaluates the effect of a proposed development on the trees identified in the BS5837 survey. It details which trees need to be removed, which can be retained, and what protective measures are required during construction to prevent root damage, soil compaction, and changes to drainage.

We produce AIAs as a standalone document or as part of a combined BS5837 report, depending on the stage of your project and the requirements of the local planning authority. We work alongside your design team to find solutions that retain the most valuable trees while still achieving a viable site layout. Where proposals do require removals, we dovetail the survey findings with our large-scale tree removal crews so the consented works can be scheduled efficiently.

Tree Protection Plans and Method Statements

Once planning permission is granted, conditions often require tree protection plans and arboricultural method statements before work can begin on site. These documents specify exactly how retained trees will be protected during construction — including the location of protective fencing, no-dig construction methods for surfaces within root protection areas, and supervision requirements for sensitive operations.

We can also provide on-site arboricultural supervision during critical phases of construction, such as foundation excavation near retained trees or the installation of services through root protection areas. This ensures compliance with planning conditions and protects you from enforcement action.

Development Site Surveys and Tree Constraints Plans

At the earliest feasibility stage, a tree constraints plan helps your architect or site planner understand where trees will limit development. Root protection areas, canopy spreads, and shadow patterns are plotted onto the topographical survey, giving the design team a clear picture of the constraints before a single line is drawn.

Commissioning this early saves money. It is far cheaper to design around a high-value tree than to discover mid-application that the planning authority will not accept its removal. Where retained trees are protected, our tree preservation order specialists can advise early on what the council is likely to accept.

Our Qualifications and Reporting Standards

All tree surveys and risk assessments are carried out by qualified arboriculturists with the appropriate level of professional accreditation. Our reports follow the most current editions of BS5837:2012 Trees in Relation to Design, Demolition and Construction, and are formatted to meet the submission requirements of every council we work with across Hertfordshire, Buckinghamshire, and the London boroughs.

We carry professional indemnity insurance for all survey and consultancy work, and our public liability insurance covers any subsequent arboricultural works we carry out on your behalf.

Areas We Cover

We carry out tree surveys and risk assessments across our full 30-mile service area from our base in Watford, covering Rickmansworth, Harrow, St Albans, Hemel Hempstead, Barnet, and all surrounding areas in Hertfordshire, Buckinghamshire, and North London.