The compelling case for retaining trees in new developments

min read time
2023-01-13 09:27:59

There are distinct signs that the UK public’s love affair with mature trees is increasing.

Although people have always enjoyed a tree-filled landscape, the pandemic brought trees to the front of public consciousness. With all other forms of entertainment curtailed during the lockdown, people increased the time they spent in nature, with 43% saying visiting green and natural spaces had been more important to their well-being during the pandemic.

If we look at pro-tree activism in recent years, it’s clear that people want mature trees in their environment – and will fight to keep them. Sheffield is the most high-profile case and the Sheffield residents’ battle in 2019 to keep mature street trees resulted in mass protests, arrests and riot police on suburban streets. Indicative of how strongly people feel about mature trees, there have been similar situations around the country and there are signs that the government is listening.

Developers face a balancing act

It can be hard to reconcile the public’s love for mature trees with the frequency that developers and planners seek to remove them from new build sites. However, the key to understanding this lies in the trees themselves.

Building around mature trees in a way that gives the tree a strong chance of flourishing in the longer term can be difficult. There’s a high likelihood that any disturbance of their root system will cause the tree to die, bringing safety issues for housing around it and greater complexity for the developer in creating sufficiently large buffer zones around the tree.

Mature trees can also pose a risk to the infrastructure of new build housing, with root ingress to pipework a significant issue in blocking drains – and a costly one to fix. What’s more, their wide root systems will react to drier summers triggered by climate change by looking further for water, meaning roots are more likely to meet pipework.

When balancing these factors with the many aesthetic, health-giving, shade-producing and carbon-reducing benefits of mature trees, developers often choose to avoid potential problems by opting to remove them and plant saplings instead.

With effective products now available that safely divert roots from pipes, it’s time to think again about the role of mature trees in new developments.

Government policy increasingly values mature trees

The latest government thinking appears to support this rethink, recognising the value of trees and the importance of including specific guidance about trees in planning policy, particularly around the creation of tree-lined streets in all new developments. Mature trees offer many benefits that would take years to come to fruition with new saplings and it is crucial we plan for those too.

January 2020 Building Better, Building Beautiful Commission report included three significant changes. Firstly, it recommended that two million new street trees should be planted within five years. Secondly, it raised the value profile of trees, directing that local councils should consider trees “as essential as the structure of a road or surface water drainage”. And thirdly, it stipulated that planning should “take place up-front with the presence of trees as a given”.

This report echoes a government emphasis on ‘beautiful placemaking’ that it intends to legally enshrine in the planning system for both urban and natural environments. This pledge, together with the commission report, will feed into a government consultation on a set of new National Model Design Codes that will provide guidance for local authorities and developers on shaping new developments.

This is likely to enhance the current UK planning system where local planning authorities have a statutory duty to consider the protection and planting of trees when granting planning permission for proposed developments. Planning conditions are frequently used by local planning authorities as a means of securing the retention of trees, hedgerows and other soft landscaping on sites during development and for a period following the completion of the development.

Increasingly, planning regulations are going to mean developers have to rebalance their thinking about mature trees. Although mature trees add complexity to their development, as policy strengthens, they’ll need to find effective ways to manage the situation to preserve trees, turning to innovative products proven to protect against root ingress and the costs of drain repairs. This will free them up to welcome the tangible benefits mature trees offer in their development.


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Mature trees improve health and wellbeing

Mature trees offer a wider range of incredible benefits to individuals and wider society. Their contributions to sustainability, alone, are impressive. Trees are very effective at mitigating the effects of air pollution, primarily by intercepting airborne particles, but also by absorbing ozone, sulphur dioxide, nitrogen oxides and ammonia. Trees naturally absorb carbon dioxide, helping to create a carbon sink that sequesters carbon.

Mature trees can also attenuate water flow, reducing the impact of heavy rain and floods, and potentially improving the effectiveness of Sustainable Drainage Systems (SuDS). In fact, trees moderate local microclimates, through a combination of reflecting sunlight, providing shade and evaporating water through transpiration. Trees help to limit the ‘urban heat island’ effect - urban areas with mature trees are cooler in summer and warmer in winter.

The shade question is critical when choosing between retaining mature trees, or replacing them with saplings in an urban setting. Established mature trees not only mitigate the urban heat island effect, but they often require lower maintenance than younger trees. Saplings, however, react to the dry areas of an unshaded urban heat island by reaching their roots out further to establish themselves, risking disruption to pipework and unattractive pavement lifting.

A well-placed mature tree can also improve the environmental efficiency of a building by acting as a sunshade, reducing thermal gain in summer.

The health benefits of living near mature trees are considerable, too. A tree-filled environment encourages exercise that can reduce the incidence of heart attacks, high blood pressure and type 2 diabetes. By improving air quality, trees also help to cut asthma levels. Then there are the multiple psychological benefits. Trees are so powerful that simply sitting in a room with tree views brings short-term benefits such as a reduction in anxiety and an increase in calmness. It’s even been observed that when patients can see trees from their beds, they recover faster.

Change is coming

All these factors are coming together to promote a greater valuing of trees by individuals, communities, authorities and government. Are we witnessing a tree revolution?

If we look at what’s happening in Sheffield today, we can see signs of a complete change of direction in tree policy. The city has gone from a controversial tree-felling programme to sharing a £2.9 million "emergency tree fund" from the Woodland Trust to help plant trees and create green spaces in its communities. The 'Treevitalise' scheme will see more trees planted across the city and engage citizens in the planting, care and appreciation of their trees, woods and greenspaces. 

Perhaps Bristol, one of the greenest cities in the UK, is the best indication of where tree policy is going. Bristol’s planning policy specifies that “individual green assets should be retained wherever possible and integrated into new development” – effectively directing that buildings should work around existing mature trees. The Bristol Tree Forum points out that retaining trees will make the planning process easier and will keep local people onside when it comes to supporting developments.

These strategies will allow local authorities to mandate that developers value tree size and the total canopy cover in a city. This is to steer away from the use of ‘stem counts’ to hide the removal of large trees and their replacement with smaller trees.

Tree programmes like these will need to work with trees and their root systems, rather than against them. It’ll be important to recognise that tree root development is affected by soil type and structure, as well as soil water content and temperature. A lot of issues can be averted by matching trees to the soil, or augmenting the soil conditions to produce root systems that stay near to the surface, avoid pipework and minimise costly damage to pavements and drainage pipes.

If trees are asked to thrive in poor soil conditions that lack water, they’re more likely to send roots deeper and wider, looking for water, air and bio nutrients – the very thing that drainage systems carry. Making mature trees viable in new developments will involve managing their root systems to minimise root penetration and protecting the pipes themselves by repelling roots.



So, what does this mean for developers?

The first thing to note is that mature trees are an emotive topic, and planning to remove them often provokes local opposition to a proposed development that can lead to protracted planning disputes. By following the Bristol trend of voluntarily incorporating mature trees into your development, you can smooth the construction process and create an environment that’s more attractive to prospective buyers.

It's worth investing time to optimise your processes for retaining mature trees in your developments. It makes sense to identify the trees that are most likely to survive development occurring around them and then to put the correct protections in place during development. The key is to get expert advice on a site’s tree plan right at the pre-planning stage.

Keeping trees will enhance your reputation as a responsible developer with strong sustainability credentials. It’s also a decision that’s good for the bottom line, because buyers will pay more for a house that’s surrounded by mature trees. A study based in North West England also showed that a view of a natural landscape added up to 18% to a property’s value, and that homebuyers would be willing to pay £7,680 per household for views of broadleaved woods. And this is before you’ve made the most of the marketing opportunities around the health benefits of living near trees.



Retaining mature trees will require ongoing maintenance and careful management of root impact on below-ground services, particularly pipes. Check out Forest Research’s guide on practical considerations for trees around buildings for advice, and consider using a root seal technology, such as OsmaDrain RootSeal, to provide added protection from trees and root ingress.

OsmaDrain with RootSeal technology uses a natural mineral additive to harmlessly repel tree roots reducing potential damage, upheaval and considerable costs. It focuses its protection on pipe joints, the most likely point where roots can get in, stopping problems before they start. There’s no need for the cost and widespread disruption and upheaval of repairs, and no environmental cost of removing trees either. And intact pipes mean there are no raw sewage leaks.



OsmaDrain means developers can give mature trees the best change of thriving for many years, despite what’s built around them. Buyers can have the mature trees they want in their living environments, and developers have an effective tool to manage the risks of trees in the development.

Find out more about OsmaDrain RootSeal from Wavin