Trees, Planning Permission and TPOs

Before you get your planning application together, be sure to consider how trees on site could affect your project, says Mike Dade
by Mike Dade
22nd July 2018

Trees can be a great asset on a plot, providing an attractive, mature setting to a new home, plus much-needed shade and shelter in the garden. They’re an important factor in planning, too, and their preservation is given a high priority. In some instances, they can be a significant hindrance to building, or even prevent it altogether. Here are the key facts you need to know about trees and planning.

Why do trees matter?

I’d hazard a guess that we can all agree on the environmental benefits of retaining trees wherever possible. They can also add value simply by making both house and garden a more pleasant place to spend time. However, in pure construction terms they can actually have an enormous effect on how and where we can build – and sometimes this impact has to be properly managed.

Surprisingly, trees and hedges themselves do not come under the remit of Building Regulations. The impact of trees on soil conditions, however, will be a factor for your building control officer to consider.

This is especially true in areas that have clay soil – and that’s around 60% of all housing land used to date. British Standard BS5837: 2012 (Trees in relation to design, demolition and construction) is a useful source of guidance.

Protected trees and the law

Tree preservation orders (TPOs) can be put in place by a local authority, thus shielding particular examples from felling, lopping or damage (including to the roots) without express written approval.

A TPO can be applied to a tree of any size or species, but those with a trunk diameter of less than 75mm would not normally be considered. If your project is in a conservation area, then every tree within that zone is effectively covered by a TPO and you will need to seek planning permission for any work involving them.

Dursley tree house is an inspiring lesson in how to work with trees on site. The brief was for an eco-friendly home that would be sensitive to its surroundings
This meant developing a design that would work around more than 25 protected trees. Click to read the full story

You can contact your local authority to check whether a specimen is protected or not – but in some cases there may be a tell-tale disc nailed on, indicating it’s on the council’s radar.

As well as creating TPOs, your local authority also has the right to vary or revoke them. This means that you can apply for a protection order to be lifted via the planning process.
View government guidance for more info.

Why can’t I just cut it down anyway?

It is a criminal offence to damage or destroy a protected tree, so the first thing to check on a plot is whether any are subject to a tree preservation order (TPO). An order can apply to individual trees, groups of trees and whole areas of woodland.

If you fell a protected tree, you’ll be leaving yourself open to the full force of the law. Penalties can be hefty,with a maximum fine of £20,000.

If no TPO is in place and you’re not in a conservation area, then you are allowed to cut down a tree that’s wholly on your property – but you still need to exercise caution. However, if the specimen is located on a shared boundary, or if felling it might pose a danger due to its size and location, you can’t just press ahead regardless.

For instance, leylandii will never be subject to a protection order, but it is likely to be positioned on a boundary – and if this is the case, then you’ll need to reach an amicable solution with your neighbours.

While for some a leylandii hedge is little more than a light-blocking monstrosity, to others it could be a source of highly-prized privacy. Passions can run high on both sides, but don’t expect your local authority to intervene in any dispute.

Tree surveys and assessment

When you make a planning application, the forms ask whether there are any trees on the site or nearby that could be affected by the proposed works. If the answer is yes, the council will expect your application to be accompanied by a tree survey. If this shows that trees could be affected, then you’ll need an ‘Arboricultural Impact Assessment’.

This additional survey identifies the trees – plus their size, age, species and quality – then rates them against criteria detailed in British Standard 5837:2005. The report also sets out the required root protection areas for the trees, which is based on their size and age. The likely impact of the works on the trees is then assessed and recommendations given as to which could reasonably be felled to facilitate the build and suitable measures to protect those remaining.

Read more: Plot assessment checklist for self builders

Don’t be surprised if your planning permission dictates you’ll need to use engineered foundations (usually a piled solution) to protect any mature roots. This will come at an additional cost, which is rarely reflected in the finished valuation of a new property, so should be factored into the plot’s selling price before you buy.

Already got planning?

If you’ve already been granted full planning permission for your self build project, then this will override any TPO that’s been in place – so the relevant trees can be felled to make way for the new building.

Be careful before you start firing up the chainsaw, though. Planning consent will invariably have a number of conditions attached, and those referring to trees can run to several pages.

The Baker's self build site featured two 150-year-old oak trees, subject to preservation orders, only 8m away from their proposed build area
During construction, the couple had to work carefully to avoid damaging root protection zones. Click for the full story

Restrictions may include measures to avoid compaction of soil, specifications for trench locations, details of how to store any heavy materials and a requirement for barriers of fencing to protect the trees and root systems of specimens due to remain. In addition, where permission has been given for removal, you will probably be expected to replace any losses with new planting.

Problem plants on site

Trees can be a restrictive factor on where you can physically build on site. They can obstruct light and views, and can interfere with visibility at the access from your plot onto the road. Root systems can also create problems including cracks in concrete or drainage pipe runs.

Slippage is another common problem, caused when trees draw huge quantities of water up from the soil. When moisture is removed, soil can shrink, which can lead to subsidence and foundation issues. The reverse happens if you extract a mature tree. The moisture that it would have consumed instead stays in the ground and can eventually build up, creating hydraulic pressure that will push against underground structures; a process called heave.

Don’t assume that just because you don’t mind a tree close to your house, the local authority will be happy with it.

Protected trees can be felled where they’re creating a nuisance, damage or danger. Where trees are affected by or in the way of your build, you have a number of options as to how to make progress. First up there’s negotiation, probably involving replacement planting proposals.

Next up is further assessment, both of the trees themselves and also to show that they add little to the local landscape or local character. Your other option is the so called ‘pre-emptive strike’ approach, which involves removing the problem trees before you make a planning application.

Let’s look at each of these in more detail:

Negotiating with the planners

Putting forward proposals for replacements with your application is a good way to deflect objections to the loss of existing trees. But do look carefully at what species any replacements should be and where they would be best deployed. There might be an advantage in getting advice from a garden designer, so that an integrated landscape proposal can be put forward. Councils routinely impose landscaping conditions when granting permission for new houses anyway, so having a scheme drawn up before an application goes in might save having to prepare one later.

Further assessment

Occasionally, a second inspection of a tree reveals issues not evident at first. In one example, a fine protected lime tree was preventing an extension to a house, but a second opinion on its health revealed a cavity in its trunk that significantly reduced its life expectancy and justified its felling.

The question of the importance of a tree in landscape terms is inevitably quite subjective, but if you feel a tree report has over-egged the importance of a tree, have a close look yourself. Planning is generally most concerned with public views of a property so check views from all roads and footpaths in the vicinity.

Pre-emptive strike

If trees on your site are in the way but not protected, you’re entitled to remove them. However, this ‘pre-emptive strike’ approach tends to alarm neighbours who in turn might tip off the council’s tree officer.

Tree officers can take exception to not having been consulted, despite the fact that you’re not under any obligation to do so. You have to weigh the possibility of making enemies (and creating objectors) before you’ve even submitted your application against the risk of your site being rendered undevelopable if the council decide you can’t remove trees that would obstruct your build.

Note that councils sometimes impose TPOs when planning applications are made, just to gain that extra element of control and prevent any pre-emptive felling, so if you’re going to fell, be sure to do it well in advance of your application.

Land where a tree, especially a large one, has recently been felled may be subject to ‘heave’ where the soil swells, taking up moisture previously claimed by the tree. This needs to be taken into account in your foundation design, so make sure you notify your building designer.

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