Building in Buckinghamshire: Green Belt, Conservation Areas and Protected Trees

Gerrards Cross and Beaconsfield sit under some of the tightest planning layers in England. Here is what each one actually restricts, and what it doesn’t.

Green Belt catches people out because they hear the word “protected” and assume nothing can be built. That is not how it works. Green Belt policy is aimed at stopping open land being swallowed up. It restricts new houses on undeveloped plots, but a good deal still gets done: replacement dwellings, extensions, outbuildings, driveways, drainage, landscaping. The usual test is whether the work counts as “inappropriate development”, and an extension is generally acceptable if it is proportionate to the original house. What counts as proportionate is set by local policy and argued over daily, so check with your local planning authority before you get attached to a scheme. Which council that is depends on which side of a boundary you sit, and there is a list at the end of this guide.

“Original house” is the phrase to watch. As a rule of thumb it means the house as first built, or as it stood in the late 1940s, not as you bought it. If a previous owner added a wing in the eighties, that extension has already used up part of your allowance. Buyers in Gerrards Cross and Beaconsfield discover this more often after completion than before.

The Chilterns National Landscape

A large slice of Buckinghamshire sits within the Chilterns National Landscape, the newer name for the Chilterns Area of Outstanding Natural Beauty. The designation doesn’t change what needs permission so much as how hard applications are looked at. Expect closer scrutiny of materials, levels and anything visible from the wider landscape: retaining walls, terracing and big level changes get judged properly rather than nodded through, and flint and brick tend to go down better than rendered blockwork. The boundary runs through some odd places, so if you think you’re outside it, check the council’s mapping rather than guessing.

Conservation areas

Both Gerrards Cross and Beaconsfield have conservation areas, and the old town in Beaconsfield is tightly drawn. Inside one, two things change for a homeowner. First, demolishing most structures, including some walls and outbuildings, needs consent. Second, the council may have made what is called an Article 4 direction, which strips away permitted development rights, so work that would be automatic elsewhere, such as a new driveway or a change of boundary treatment, may need a full application. It varies street by street. The council’s own maps will tell you whether one covers your road, but be careful what weight you put on a phone call. Ask a planning officer whether your job is permitted development and you will get a view, not a decision. It is informal, not binding on the council, and no protection if someone takes a different line later. The binding answer is a lawful development certificate: an application in its own right, decided by the council, and once granted it is the legal confirmation that the work is lawful.

Driveways carry an extra wrinkle everywhere in England, conservation area or not. Lay an impermeable surface over more than five square metres between the front wall of the house and a highway and you need planning permission, unless the run-off is directed to a permeable area within your own boundary. Permeable construction usually deals with it, though on clay that takes designing rather than assuming. Getting the car across the footway is a separate consent again, from the highway authority rather than the planners. Our driveway guide covers both, and the build-ups.

Protected trees, and where you can dig

A tree preservation order makes it an offence to cut down, top, lop or damage the tree without the council’s written consent, and “damage” includes the roots you cannot see. Take one down, or damage it badly enough to destroy it, and you have committed a criminal offence under section 210 of the Town and Country Planning Act 1990. There is no ceiling on the fine. It is unlimited, in the magistrates’ court or the Crown Court, and the court is required to take account of any financial benefit that came, or was likely to come, from the offence. Clear a tree that makes a plot easier to build on and the sum is worked out with that in mind. Lesser breaches of an order carry a lower, capped fine, and the duty to plant a replacement tree in the same place sits on top of whatever the court orders. Not knowing about the order is no defence. But for anyone digging, the order itself is only half the story. The other half is the root protection area.

The root protection area, or RPA, comes from the British Standard for trees on construction sites. As a rule of thumb it is a circle with a radius of twelve times the trunk diameter, measured at chest height. A mature beech with an 800mm trunk therefore commands a circle nearly twenty metres across. Inside that circle, excavation, compaction, spoil heaps and even repeated wheel tracking can kill the tree slowly. The damage shows two or three summers later, long after the diggers have gone.

The roots were there before the drawings. The job is to design around them, not argue with them.

None of which means you cannot build near a fine old tree. It means the method changes:

Private roads

Gerrards Cross in particular is full of unadopted roads, many run by residents’ associations. The tarmac and the verges are private property, and a groundworks job means heavy wagons, muck-away lorries at twenty-odd tonnes, running over a surface that was never built for them. Expect the association to want an access agreement before work starts: a condition survey of the road, a damage deposit or bond, agreed hours, and sometimes a weight limit that forces smaller wagons and more trips. That last one affects price, so raise it before anyone gives you a firm figure.

Who to talk to

Three conversations sort out most of the above before any steel is ordered:

• The local planning authority, whichever council your postcode actually falls in. Across most of the area this guide covers that is Buckinghamshire Council, a unitary authority. Cross a boundary and it changes: Cookham comes under the Royal Borough of Windsor and Maidenhead. Chorleywood, Rickmansworth and Moor Park come under Three Rivers District Council in Hertfordshire, and Northwood under the London Borough of Hillingdon. Green Belt, conservation areas and tree preservation orders work the same way in all of them, because it is national law, but the local policy that interprets them, and the fees and forms, do not. In the two-tier part of Hertfordshire, note that anything touching the road is the county council rather than the district. Most run a pre-application advice service: it costs a little and can save a redesign, and for anything in the Green Belt or a conservation area it earns its fee.
• An arboricultural consultant, for the tree survey, the RPAs and the method statement. On a wooded plot, appoint one before the footprint is fixed, not after.
• A structural engineer. Where foundations must bridge roots, cope with level changes or sit near retaining structures, the engineer’s design is what turns the method statement into something buildable.

A groundworks contractor used to working under these constraints will ask about all of this at the first site visit. If nobody mentions trees, the road or the conservation area boundary, that tells you something too.