BS5837: 2012 Trees in relation to design, demolition - Arboricultural ...

BS5837: 2012 Trees in relation to design, demolition and construction 

AA Road show presentation notes: Richard Nicholson May-July 2012 

Edited by Mike Sankus 

The BS Review Group comprised: 

ñ� Ian Phillips Landscape Architect; 

ñ� Clive Entwistle, Engineer; 

ñ� Mike Volp, Arboricultural Officer LPA; 

ñ� Jim Smith, Arboriculturist. With the Tree Design Action Group; 

ñ� Mick Boddy, Arboricultural Consultant; 

ñ� Julian Forbes-Laird, Arboricultural Consultant. 

BS5837:2005 had been tested in various forums which helped the Review Group prepare 

a draft document for public consultation. The review group looked at what had worked and 

what had not and amended the document accordingly, adding entirely new sections to the 

first draft where relevant. Forums included: 

ñ� Planning meetings, 

ñ� Pre application meetings 

ñ� LPA recommendations 

ñ� Consultant recommendations 

ñ� Examination at appeal 

What worked What didn’t 

Flow process. 

Figure 1 stopped cherry picking to 

a certain extent and set out a 

process 

Tree survey first 

Cascade Chart for tree 

classification was appreciated by 

non-arboriculturists, e.g. Planning 

Inspectors as it saved arguments 

amongst arboriculturists about 

different systems 

RPA as an area was understood 

as was the idea of adjustment to 

suit site conditions 

Constraints mapping, useful to 

represent the 3D tree in 2D and 

issues about liveability 

Section 13 'Design considerations 

for new planting.' Use of landscape 

architect and design advice for new 

schemes. 

Mitigation planting 

Flow process became a sequence of 

discrete steps, which were almost an 

end in themselves. Tick boxes not the 

process 

‘R’, which was frequently confused 

with meaning remove or retain? 

Became ‘U’ 

Multi stemmed trees calculation did 

not work 

‘open grown’ not explained properly in 

the text 

Overzealous use of sunlight 

arguments. Its rarely a ‘no’ 

Sunlight only, rather than sunlight and 

daylight was taken into account 

Tree Constraints Plan became an 

entity required by LPA. 

Arboricultural Method Statement




Protecting areas of the site from 

construction activity that are 

reserved for new planting 

Type of fencing, more realistic and 

the use of ground protection 

3D cellular confinement systems 

better than 2D 

Statements about details in 

subsequent drawings 

became process driven or worse still, 

formulaic. What is the objective? 

CEZ just another TLA? Muddled 

description was not helpful. 

Figure 3 

Fence diagram Fig 2 poorly drawn 

and too prescriptive 

RPA definition 

Section 11 advice to builders, now 

included in an informative annex 

3m or 20% references were muddled 

so the 3m reference was dropped 

Title 

The new title reflects the entire development process. Construction is defined as site-based 

operations, but the consideration of trees on a development site needs to start before then. 

Demolition frequently occurs before planning consent is sought or granted, subject to 

planning conditions. 

Foreword. 

BS5837: 2012 came into effect on 30 April 2012. BS 5837: 2005 was withdrawn the same 

day. Figure 2 and figure 3 of the new standard (fencing details) can be reproduced without 

infringing copyright. 

Use of the document 

Execution of its provisions is standard British Standard wording for all standards. 

Introduction 

Benefits of trees highlighted and for the first time the term ‘Green Infrastructure’ is included. 

The importance of trees as 'material considerations' in the planning process is highlighted. 

Mentions that level of detail required will vary from planning application to planning 

application. Aligns with government advice on validation of planning applications. 

Figure 1 sets out the process based on RIBA work stages and sets out the main chapter 

headings in the standard, using a similar language. For example section 5 has Conception; 

Section 6 has Design and Technical. 

Section 1 - Scope




BS 5837:2012 applies whether or not planning permission is needed. For example, 

permitted development. 

Section 3 – Terms and definitions 

Paragraph 3.1 - Access facilitation pruning is limited by the need to ensure pruning works 

do not have a significant adverse impact on retained trees and are limited to what is 

necessary for access only. 

Paragraph 3.2 – There is a better definition of the Arboricultural Method Statement, which is 

needed for any aspect of development, including demolition, where it lies within the RPA. 

No definition of Tree Constraints Plan, but there is a statement about plotting constraints on 

relevant drawings in paragraph 5.2 to reflect the importance of this part of the process. 

Paragraph 3.7 – There is a better definition of the Root Protection Area, which treats the 

protection of roots and soil structure as a priority. RPA is just about the only abbreviation in 

the standard. 

Section 4 - Feasibility: surveys and preliminary constraints 

Paragraph 4.1 – There is information about scales and copying of plans, the use of a scale 

bar and monochrome statements. 

Paragraph 4.3.1 - Soil assessment. This was included at the request of engineers and 

landscape architects. This is not necessarily a detailed survey and may not be undertaken 

by the arboriculturist, but must be fit for purpose. 

In some circumstances the soil assessment could result in a larger RPA than that 

prescribed in Annex D for a given stem diameter. 

Paragraph 4.4.1.1- Concerns the timing of tree surveys to ensure it is available to designers 

prior to formulating design proposals. 

Paragraph 4.4.1.3 – There is new advice for Local Planning Authorities about not relying on 

planning conditions to secure a tree survey. The tree survey is an important part of the 

evidence base used at the design feasibility stage and must form part of the planning 

application at validation. 

Paragraph 4.4.2.2 – Within the context of proposed development. This is about land use 

allocations and principles of types of development as defined in local plans (see National 

Planning Policy Framework). For example, residential, golf course etc. It is NOT the details 

of a particular development design for a site that forms part of an outline or detailed 

planning application. 

Paragraph 4.4.2.4 – This is new advice on the management of trees within groups 

Paragraph 4.4.2.6 - Concerns measurement conventions. BS uses SI units




Paragraph 4.4.2.9 – Provides information about shrinkable soils and hedgerows. This was 

added at request of engineers 

Paragraphs 4.5.3 & 4.5.7 - Tree categorisation no longer uses R as a tree grade and 

includes U instead. The reason for using U and not R is that it removes any assumption that 

R = Remove. 

Paragraph 4.5.4 - Generally the same weight is accrued for each subcategory as before 

(see below). The sentence "would not accrue added value" was present in BS 5837:2005, 

but is no longer in the text. Effectively it’s the same as it was, but the Note is in the wrong 

place in the process. 

The note in BS 5837:2005 at the end of the table: "Whilst category C trees will usually not 

be retained where they would impose a significant constraint on development, young trees 

with a stem diameter of less than 150mm should be considered for location" has been 

taken out of the standard and does not appear in BS5837: 2012 because Table 1 is about 

gathering the data in order to make decisions, not about condemning a tree before all the 

data has been gathered. 

Paragraph 4.5.7 - Upgraded means it’s a U grade tree, based on 3 bullets, but its 

conservation, heritage, landscape or cultural values make a case for it to be upgraded to a 

C grade tree for the short term. This of course is subject to the safety issues also mentioned 

in this paragraph. 

Paragraph 4.5.8 - The reference to irremediable diseases applies to serious ailments, which 

have a significant impact on the safety of a tree in the short term. For example Inonotus on 

Plane or nail galls on a Lime shouldn’t downgrade a tree which would otherwise be graded 

A, B or C to a U grade tree. The same logic applies to the third bullet point under U grade 

trees in Table 1 

Table 1 - Remaining life expectancy is used in BS 5837:2012, rather than ‘substantial’ or 

'significant' contribution as in set out in BS5837: 2005. Trees can contribute when they are 

dead. Trees graded A , B or C are largely about trees that are not dead. 

OED Definitions – 

Quality: Distinguishing characteristic, the character or nature of something. 

Value: Desirability in respect of some property. 

Paragraph 4.5.10 - Young trees were raised as being important by the review group in DPC 

but there was no support for this view so it was removed. 

Paragraph 4.5.11 – There is a definition of veteran in paragraph 3.12 which is taken from 

BS 3998: 2010. The importance of veteran and ancient trees is highlighted here. Both are 

classed as A3 grade trees because there was a feeling that an ancient, largely dead tree 

could, under BS5837: 2005 could too easily be classified as an R grade tree.




Paragraph 4.6.1 – The RPA refers to Annex D, which provides the radius based on 

measured stem diameter @1.5m. It saves the calculation and prevents ridiculous RPA's 

with too many decimal places. It was requested at public consultation. 

The drawings at Annex C are based on those from Australian National Standard. 

Multi stemmed trees are based on cross sectional stem diameter not area. 

Paragraph 4.6.2 - The frequently misused term ‘Open grown' found in BS5837: 2005 has 

been removed and replaced with new wording in BS5837: 2012. 

Paragraph 4.6.3 - The list order has been changed and the phrase ‘when known’ has been 

omitted from BS5837: 2012. 

Section 5 - Proposals: conception and design 

Paragraph 5.1.2 - Project arboriculturist appears for the first time and stays until section 7 

Demolition and construction in proximity to existing trees. 

Paragraph 5.2.2 – Refers to designs which should avoid unreasonable obstruction to light 

and refers to BR 209, which is frequently used by planners to assess daylight and sunlight 

issues. It contains a specific appendix on trees. 

Paragraph 5.2.3 (f) - Solar collectors are referenced. See Thayer - Solar access and the 

urban forest. Arboricultural Journal, 1983. Volume 7 

Paragraph 5.2.4 – There is a note concerning climate change resilience and the 

contribution of large species. Emphasises the need to take care at conceptual and design 

stage for successful integration of healthy trees. 

Paragraph 5.3.1 – The heading ‘Proximity of structures to trees’ in BS5837: 2012 replaces 

'proximity of trees to structures’ in 6.3 of BS5837: 2005. 

There is a new default position, which states that all structures should be sited outside the 

RPA of trees to be retained unless there is an overriding justification and the project 

arboriculturist can demonstrate that it would be acceptable to do otherwise. 

Paragraph 5.3.2 - The cumulative effects of incursions into RPAs was only a note at 6.2.3 

of BS5837: 2005. It is now a significant consideration in BS5837: 2012. There is a new 

consideration regarding the acceptability of further activity within the RPA. 

Paragraph 5.3.4 - Shading is better defined and the mix up of sunlight and daylight has 

been rectified in BS5837: 2012. The benefits of shading are spelled out better than it was in 

BS5837: 2005. See also paragraph 5.2.2. 

Sub section 5.4 - Arboricultural impact assessment 

This is not an implications assessment (new wording). This assessment evaluates the 

effects of the proposed design, including potentially damaging activities such as removal of 

existing structures and the location and dimension of all proposed excavations or changes




in levels. It also deals with the buildability of the scheme. This includes recommendations 

for any necessary mitigation. 

Items at paragraph 5.4.3 were included in the Arboricultural Method Statement in BS5837: 

2005. The Arboricultural Impact Assessment is a document that Local Planning Authorities 

should require at the planning application stage, prior to validating a planning application. 

Sub section 5.5 - Tree Protection Plan 

The construction exclusion zone is better defined but downplayed in BS5837: 2012. It was 

heading 9 in BS5837: 2005. It’s now the area inside what would usually, but not always be, 

the vertical barriers. In some circumstances ground protection could be considered 

appropriate or a combination of both but it remains the area within the barriers that is the 

construction exclusion zone. 

Sub section 5.6 - New planting design and associated landscape operations 

New planting design and associated operations has been brought into BS5837: 2012 at this 

early stage because it sits comfortably within the Conceptual Design stage of the RIBA 

work stages. 

This is still prior to planning permission or client approval if no planning permission 

is needed (permitted development?). 

There is a useful commentary on the importance of trees in design and landscape. 

Section 6 - Technical design 

At this stage planning permission has been given and the following will have been 

completed and where appropriate submitted with the planning application for validation 

purposes. 

1) Topographical survey 

2) Soil assessment 

3) Tree survey 

4) Tree categorisation 

5) Tree constraints and RPAs are identified and used to influence design 

6) Arboricultural Impact Assessment (see list at paragraph 5.4.3) 

7) The issues to be addressed by an arboricultural method statement. Includes 

heads of terms of Arboricultural Method Statement to provide certainty of outcome. It 

relates to advice in paragraph 5.4.3 (h) mentioned above. 

8) Landscape proposals 

9) A tree protection plan (see level D of Fig 1)




10) Special engineering within RPA and other relevant construction details referred 

to in paragraph 6.1.2 (d & e). Commentary on clause 6 refers to draft form or heads 

of terms sufficient to provide a high level of confidence, but also see paragraph 

7.1.3, which makes clear that technical feasibility should be tested at planning 

application stage by submitting details with the planning application (prior to 

validation). See also paragraphs 7.2.1 and 7.5.5, which give more useful guidance 

on works inside the RPA and paragraph 5.3.1, which sets the default position and 

parameters of rational to undertake operations within the RPA. . 

Sub section 6.1 - Arboricultural Method Statement 

What is an Arboricultural Method Statement and when are they relevant? See paragraphs 

6.1.1 through to 6.1.3 for details of what may be included. They apply whenever any aspect 

of development lies inside the RPA (see paragraph 3.2). It's about implementation. 

Paragraph 6.1.2 - The Arboricultural Method Statement should be appropriate to the 

proposals. 

Paragraph 6.1.2e) – This is an important statement for certainty of outcome. 

Paragraph 6.1.3 – Method statement should include a list of contacts for the development 

to ease communication. 

Sub section 6.2 - Barriers and ground protection 

OED Definitions: 

Barrier: ‘anything serving to obstruct passage or to maintain separation, such as a 

fence’ 

Fence: ‘structure that encloses an area’ which could be a chain on posts. 

Paragraphs 6.2.2.2 and 6.2.2.3 – These set a default specification and the alternatives 

where circumstances allow for an alternative specification for the barrier. 

Paragraph 6.2.3.3 - Ground protection solutions are provided in this paragraph, which 

contains more information. There are three suggested scenarios in BS5837: 2012, which is 

an improvement over BS5837: 2005 which only referred to ‘engineered’ and ‘fit for 

purpose’. 

Section 7 - Demolition and construction in proximity to existing trees. 

Paragraph 7.1.1 - Makes clear that the tree and soil structure inside the RPA takes priority 

when considering construction inside the RPA (see paragraph 3.7 - definition of RPA, which 

talks about maintaining tree’s viability and where the protection of roots and soil structure is 

a priority). See also paragraph 5.3.1, which states that the default position is that structures 

are located outside the RPA of trees to be retained. In BS5837: 2005 there was the 

flexibility to allow a 20% setback of the RPA, but this no longer applies. The assumption 

now is that it is not a given: building in the RPA was considered acceptable and almost the




default in BS5837: 2005 because the standard apparently said you can, but now the 

message is very clear and it cannot be assumed that you can build in the RPA. 

Paragraph 7.1.3 – This is very important. Notwithstanding the fact that commentary on 

clause 6 and paragraph 6.1.2 (e) intimates that details of foundation design inside the RPA 

might follow planning consent (at condition stage), this paragraph 7.1.3 makes clear that 

technical feasibility of proposal for construction inside the RPA should be tested at planning 

application stage by submitting details with the planning application for validation. It also 

links to paragraph 7.7.2 and annex B (Table 1 planning applications). 

For works outside the RPA see Annex B (Table1 Reserved matters/planning conditions). 

Paragraph 7.2.1 - Gives useful guidance on what cannot happen inside the RPA and what 

might be acceptable if it can be justified in arboricultural terms 

Paragraph 7.3.1 - Relates to access facilitation pruning, but the extent must be considered 

in light of paragraph 3.1 which reiterates the need to ensure pruning works do not have a 

significant adverse impact of retained trees. See BS3998: 2010 and in particular text 

relating to limitations of crown lifting. 

Sub section 7.4 - Permanent hard surfacing within RPA 

THIS SECTION DOES NOT APPLY TO VETERAN TREES 

Paragraph 7.4.1 - Note relates to site-specific conditions and the expert advice of an 

arboriculturist. 

Paragraph 7.4.2.1 - Makes clear that design should not require excavation inside the RPA 

other than for the removal of turf. 

Paragraph 7.4.2.3 - The acceptability of 3m or 20% incursion into the RPA contained in 

BS5837: 2005 was frequently misused or misunderstood. BS5837: 2012 limits incursion to 

20% of existing UNSURFACED area. This is repeated in paragraph 7.5.3, which also points 

out that it must bear on existing ground level. This applies to hard surfacing and buildings 

alike, as the impact is similar. 

Paragraph 7.4.2.4 – Mentions that de-icing salt needs an impermeable barrier because of 

the damaging effect of de-icing salt in solution on tree roots. This issue needs to be 

considered when drafting the Arboricultural Impact Assessment (see paragraph 5.4.3 h). 

Paragraphs 7.4.2.5 & 7.4.2.6 - These paragraphs are all about permeable surfacing 

requirements. 

Paragraph 7.4.2.6 - Arboriculturists should reference Morgenroth and Buchan 'Soil moisture 

and aeration beneath pervious and impervious pavements’. ISA Landscape Below Ground. 

Volume III. 

Paragraph 7.4.2.7 - Highlights the need to consider the performance of surface from the 

point of view of future tree growth.




Paragraph 7.4.2.8 – Recognises the need to consider finished levels of no dig construction 

adjacent to damp proof course and/or finished levels of garage floors, which is often 

overlooked. This paragraph provides new information about levels in relation to other 

structures 

Sub section 7.5 - Special engineering for foundations within the RPA 

Paragraph 7.5.1 - Site-specific construction of specially designed structures inside the RPA, 

but needs to take account of advice in other parts of BS5837: 2012. In particular 

paragraphs 7.2.1 and 7.5.5, which gives more useful guidance on construction methods 

and paragraphs 5.3.1 & 7.5.3 which set the default position and parameters of rational to do 

undertake operations within the RPA. 

Paragraph 7.5.4 - Where a system like Housedeck is proposed the view of the appointed 

Building Control service needs to be taken into consideration to ensure it is acceptable. 

Paragraph 7.6 - Subterranean structures included at the request of LTOA. Not proven with 

current levels of understanding and practice, but 6 bullets to consider by those mentioned in 

6.2. 

Appendix A and B 

Annex A - Gives general advice for builders and other interested parties. Annex A contains 

some text from BS 5837:2005 and some of the old Annex C in the same standard 

Informative. They provide general advice about trees aimed at builders etc. Arboriculturists 

should know all this. 

Definitions: Normative: a prescriptive part of the Standard, which describes what ought to 

be done within the application of the Standard e.g. 'should' requirements. 

Informative: supplemental information and guidance, which helps with the conceptual 

understanding. Not a requirement and does not compel compliance. 

Acknowledgement 

I am grateful to Mike Sankus for his time and effort in checking these notes and carrying out 

some valuable editing following the road shows.

BS5837: 2012 Trees in relation to design, demolition - Arboricultural ...

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