Building Control Surveys & Reports:
Why Trees Must Be Considered Before You Build

Trees are one of the greatest assets a property can have. They provide shade, character, wildlife habitat, privacy and a sense of maturity that cannot be recreated quickly. Yet when an extension, new home, garage or other structure is proposed nearby, the relationship between the tree, the soil and the foundations must be properly understood. This is where professional Building Control Surveys & Reports become essential.

Arbor Cultural is pleased to be featured on page 26 of the digital Southern Green Home Guide. The guide brings together practical information for homeowners who want to improve, extend or build more sustainably. Our inclusion reflects an important point that is sometimes missed during the early stages of a project: sustainable construction is not only about insulation, energy use and materials. It is also about designing buildings that respond intelligently to the existing landscape.

A tree-related building control report gives the project team reliable arboricultural evidence before costly decisions are fixed. It can help the Building Control Body, structural engineer, architect, warranty provider and homeowner understand whether nearby vegetation may influence foundation design, drainage, construction access or long-term ground movement. Most importantly, it replaces guesswork with site-specific information.

Why Trees Become a Building Control Issue

Building Regulations do not regulate trees themselves. However, foundations must be capable of safely transferring building loads to the ground, and the performance of that ground can be influenced by vegetation. The official Planning Portal summarises the position clearly: building regulations do not apply to trees and hedges, but foundations can be affected by tree roots and soil moisture. The structural requirements for foundations sit within Approved Document A.

This is particularly important where the soil contains shrinkable clay. Clay soil changes volume as its moisture content changes. Trees draw water from the ground through their root systems, and higher water-demand species can contribute to seasonal drying over a wide area. If foundations are not designed for the relevant conditions, differential movement may occur, potentially leading to cracking and distortion.

The solution is not automatically to remove every nearby tree, nor is it simply to make every foundation as deep as possible. A proportionate design requires accurate information about the trees, their likely future growth, their distance from the proposed structure and the nature of the ground. The arboricultural survey provides part of that evidence, while the structural or geotechnical professional remains responsible for the final foundation design.

What Is a Building Control Tree Survey?

A Building Control Tree Survey is a targeted arboricultural assessment prepared to support foundation and construction decisions. It is commonly requested when trees are growing on the site, on adjoining land or within a distance that may be relevant to the proposed works. The survey may be commissioned before an application is submitted, after a Building Control Officer asks for further information, or during detailed design when an engineer needs reliable tree data.

At Arbor Cultural, the survey is designed to provide the technical information required for informed assessment against the relevant project criteria, including, where applicable, NHBC Standards Chapter 4.2: Building near trees. NHBC Standards are warranty standards rather than legislation, and the applicable requirements will depend on the project, the Building Control Body and the warranty route. Nevertheless, Chapter 4.2 is widely used as a structured method of considering tree species, water demand, mature height, distance and shrinkable soil conditions.

The Relationship Between Trees, Clay and Foundations

Moisture Extraction and Subsidence Risk

The most significant tree-related foundation issue is normally indirect rather than direct. On shrinkable clay soils, roots remove moisture and the clay can contract. The degree of influence depends on several interacting factors: the shrinkage potential of the soil, the species and size of the tree, its distance from the structure, local weather patterns, the depth and type of foundation, and the history of the site.

Species cannot be judged by reputation alone. Oak, willow, poplar and other high water-demand trees often require careful consideration, but every site is different. A mature tree at a greater distance may be less influential than a younger tree close to the proposed wall line, particularly when future growth is taken into account. Accurate identification and measurement are therefore central to a defensible report.

Heave After Tree Removal

Removing a tree does not always remove the ground-movement risk. Where a long-established tree has dried shrinkable clay over many years, its removal can allow the soil to rehydrate and swell. This process is known as heave. It is not inevitable, but it is one reason why tree removal should never be presented as an automatic engineering solution without considering the soil history, the age and water demand of the tree, and the proposed foundation system.

A carefully prepared report can help the design team compare sensible options. These may include an adjusted foundation depth, a different foundation type, engineered precautions against heave, a revised footprint or, where justified and consented, selective tree management. The objective is to reach a proportionate solution rather than defaulting to unnecessary felling or avoidable construction cost.

Roots, Drains and Physical Obstructions

Roots can also affect a project physically. They may occupy the proposed excavation zone, conflict with drainage runs or exploit defects in already damaged pipes. Large woody roots can displace lightweight surfaces or small structures, although sound modern foundations are generally more likely to be affected by soil movement than by roots physically breaking through them.

Where the position of important roots is uncertain, non-destructive investigation may be appropriate. Arbor Cultural can use techniques such as Air Spade root investigation to expose the root system with compressed air rather than damaging it with mechanical excavation. This can provide valuable evidence for foundation, drainage and service-route design.

Building Control Reports and BS5837 Surveys Are Not the Same

One of the most common sources of confusion is the difference between a Building Control Tree Survey and a BS5837 tree survey for planning. They are related, but they answer different questions.

A BS5837 survey considers trees in relation to design, demolition and construction. It is generally used to inform the planning process, identify tree quality and constraints, calculate Root Protection Areas, assess development impacts and specify protection measures. BS 5837:2012 remains the current British Standard at the time of writing and is under review.

A Building Control Survey is more directly focused on the information needed to assess the interaction between vegetation, soil and structural design. A project may require one, the other or both. Planning permission and Building Regulations approval are separate regimes, so receiving planning consent does not automatically resolve the foundation questions, and satisfying Building Control does not remove the need to comply with planning conditions, Tree Preservation Orders or conservation-area controls.

When Should You Commission the Survey?

The best time is before foundation design is finalised. Early commissioning gives the architect and engineer the opportunity to respond to the evidence without redesigning completed drawings or changing excavations after work has begun. It can also reduce delays when the Building Control Body requests additional information.

A survey should be considered for house extensions, new dwellings, substantial garages, annexes, basements, retaining structures and other projects involving foundations near trees or significant shrubs. Trees on neighbouring land matter too: roots and moisture influence do not stop at a legal boundary, and an arboricultural consultant can normally record relevant off-site trees from accessible land.

You may also need specialist advice where a tree has recently been removed, where cracks or historic movement have been reported, where clay soil is known or suspected, or where the foundation excavation reveals unexpected roots or ground conditions. In those cases, the arboricultural report may need to be coordinated with a structural engineer, geotechnical investigation, drainage survey or subsidence assessment.

A Clear Route From Survey to Sign-Off

1. Provide the project information: Supply the proposed plans, site address, any Building Control request, available soil information and details of known tree work. Good information at the outset helps define the correct scope and avoids commissioning the wrong type of report.

2. Complete the site survey: A qualified arboricultural consultant identifies and measures the relevant trees, records their condition and relationship to the proposed structure, and notes any constraints that could affect data quality.

3. Analyse current and future influence: The consultant considers species, water demand, dimensions, likely mature height, distance and available ground information. Where necessary, limitations are clearly stated rather than hidden behind false certainty.

4. Issue the technical report: The findings are set out in a concise, usable format for the Building Control Body and design team. The report should make clear what is arboricultural evidence and what must be determined by the structural or geotechnical professional.

5. Coordinate the design: The engineer uses the relevant tree and soil data to develop the foundation solution. Where the layout changes, the arboricultural implications should be reviewed before construction proceeds.

Better Evidence Supports More Sustainable Construction

Good Building Control Surveys & Reports do more than help a project pass a technical checkpoint. They support better environmental decisions. Without reliable evidence, project teams can be pushed towards two poor extremes: unnecessary tree removal or excessive foundation design. Both can carry significant environmental and financial costs.

Retaining suitable trees protects established canopy, habitat, shade and landscape character. At the same time, accurate design information can help avoid avoidable excavation, concrete use and disruption. The current NHBC Standards apply to NHBC-registered homes whose foundations begin on or after 1 January 2026, and NHBC continues to highlight the need to consider the relationship between increased tree cover, climate resilience and foundation design.

This is why the subject belongs in a green home guide. A genuinely sustainable home must be energy efficient, but it must also be durable, appropriately founded and integrated with the living landscape around it. The best outcome is a stable building and a healthy, retained tree population—not one achieved at the unnecessary expense of the other.

Arbor Cultural: Building Control Surveys & Reports

Arbor Cultural provides specialist Building Control Tree Surveys across Surrey, Sussex, Hampshire, London, Kent and the wider South East. Our role is to provide independent, technically robust arboricultural evidence that can be understood and used by homeowners, architects, engineers, developers, Building Control Bodies and warranty providers.

Every project begins with the actual site rather than a generic assumption. We identify the relevant trees, assess their likely influence, explain the limitations of the available information and set out the next steps clearly. Where a project also needs a BS5837 survey, Arboricultural Impact Assessment, Tree Protection Plan, Method Statement, root investigation or subsidence report, the work can be coordinated so that the documents support one another.

Being featured in the Southern Green Home Guide is an opportunity to reinforce a message at the centre of our work: trees should be treated as valuable design assets, but their relationship with buildings must be investigated professionally. Early advice protects the project programme, supports proportionate foundation design and creates better conditions for trees and buildings to coexist for decades to come.

If Building Control has requested a tree report, if your engineer needs tree data, or if you are planning construction near established vegetation, speak to our technical team before the foundation design is fixed. You can contact Arbor Cultural for project-specific guidance or submit your plans through our online quotation form.