Planning and building terms, explained

The words that turn up in council letters, building control forms and builders' quotes, and what each one means for a home project in England.

Most of them describe a check, a permission or a document that has to happen in a particular order. Knowing which is which is half of planning a project well. Where a limit or a size threshold is involved we have not quoted the number, because they change: check the current rules, or ask. The borough guides cover how each Surrey council applies them.

Approved Documents: The government guidance that explains how to meet each part of the Building Regulations in England, one lettered document per part. Part A covers structure, Part B fire, Part L energy and so on. They are the usual way to show compliance, not the only one, and they are updated from time to time, so the current edition is the one that counts.
Article 4 direction: An order made by a council that removes some permitted development rights in a defined area, often a conservation area. Where one applies, work that would normally need no application, such as replacing windows or adding a porch, needs planning permission. The council keeps a list of its Article 4 directions and the streets they cover.
Biodiversity net gain: A requirement that most new development in England leaves habitats measurably better than before, assessed with a standard metric. Householder applications for extensions and alterations to a home are exempt, but new houses and some larger schemes are not. Where it applies, it adds a survey and a habitat plan to the application.
Building Regulations: The national standards for how building work is carried out in England: structure, fire safety, insulation, ventilation, drainage, electrics and access among them. They apply whether or not planning permission is needed, and most extensions, loft conversions and structural alterations need an application to building control before the work starts.
Community Infrastructure Levy (CIL): A charge some councils make on new floor space to help pay for local roads, schools and open space. Many home extensions are exempt or fall under the size threshold, but the exemption usually has to be claimed in writing before work starts, and a self-build home needs its own claim. Each council publishes whether it charges and at what rate.
Completion certificate: The document building control issues when it is satisfied the finished work meets the Building Regulations. It is the record a buyer's solicitor will ask for when you sell, so it is worth getting at the end of the job rather than years later. Without it, the work may have to be opened up or insured against.
Conservation area: An area a council has designated for its special architectural or historic character. Inside one, permitted development rights are narrower, demolition usually needs consent, trees are protected and the council looks closely at materials and detailing. It does not stop you improving a house, but it changes what is likely to be approved.
Feasibility study: An early piece of work that tests whether a project is realistic before anyone commits to detailed drawings: what the house can take, what the council is likely to accept, where the structural risks are and what it might cost. Our version is the Clarity Pack. Done properly it changes the brief, and sometimes the decision to proceed.
Flood zone: The Environment Agency's classification of land by its chance of flooding from rivers or the sea, from Zone 1 (lowest) to Zone 3. In Zones 2 and 3 an application usually needs a flood risk assessment, and the council may ask for raised floor levels or flood-resistant construction. The zone for any address is on the government's flood map.
Full plans and building notice: The two ways to apply to building control. With full plans, detailed drawings are checked and approved before work starts, so problems are found on paper. A building notice skips the plan check and relies on inspections on site, which is quicker but leaves more to chance. For anything structural or involving an extension, full plans are the safer route.
Green Belt: Land around towns and cities where national policy aims to keep development open. Much of Surrey is in it. Extending an existing house is allowed in principle, but only if the result is not disproportionate to the original building, and earlier extensions count towards that. Each council sets out how it judges proportion in its local plan.
Householder application: The planning application type for extending or altering a single house and its garden: extensions, dormers, outbuildings and the like. It uses a shorter form than a full application and the council aims to decide it within eight weeks of validation. Flats, changes of use and new dwellings use other application types.
JCT contract: A standard form of building contract published by the Joint Contracts Tribunal and widely used in the UK. For home projects the Minor Works or Homeowner versions are usual. The contract sets out the price, the programme, how changes are valued, how payments are made and what happens if things go wrong, so both sides know where they stand.
Lawful development certificate: The council's formal confirmation that proposed or existing work is lawful, usually because it is permitted development. It is not planning permission, but it is proof you can show a buyer's solicitor or a neighbour. It is worth applying for even when you are confident, because an opinion over the phone is not binding.
Listed building consent: Separate permission needed for any work that affects the character of a listed building, inside or out, including some repairs and internal alterations that would otherwise need nothing. It is a criminal offence to carry out such work without it. It often runs alongside a planning application and is judged on the effect on the building's significance.
National Landscape: The new name for an Area of Outstanding Natural Beauty, such as the Surrey Hills. Development inside one is judged more strictly on its effect on the landscape, and some permitted development rights are reduced, particularly for roof extensions and cladding. The boundary is on the council's policies map and the National Landscape's own site.
Part L: The part of the Building Regulations in England that deals with the conservation of fuel and power: insulation, airtightness, heating efficiency and the energy performance of new and existing homes. It sets minimum standards for new walls, roofs, floors and windows, and for extensions it limits how much glazing can be added without compensating elsewhere.
Party wall agreement: The process under the Party Wall etc. Act 1996 for work on or near a boundary shared with a neighbour: building on the line, cutting into a party wall, or excavating close to their foundations. You serve notice, the neighbour consents or dissents, and if they dissent a surveyor draws up an award. It is separate from planning and building control.
Passivhaus: A rigorous low-energy building standard developed in Germany, based on very good insulation, airtightness, high-performance windows and ventilation with heat recovery. A certified Passivhaus needs very little heating. Full certification suits new homes best; the principles can be applied to any renovation, and EnerPHit is the version for existing buildings.
Permitted development: Work you can do to a house without applying for planning permission, because national rules already grant it: many rear and side extensions, loft conversions, outbuildings and alterations within set limits. The limits depend on the house and its setting, rights can be removed by condition or Article 4 direction, and the Building Regulations still apply.
Planning appeal: The route to challenge a refusal, a condition or a failure to decide, heard by the Planning Inspectorate rather than the council. Most householder appeals are decided on written statements and a site visit. An inspector can allow or dismiss the appeal, and the decision takes several months, so it is usually worth trying a revised scheme first.
Planning condition: A requirement attached to a planning permission that must be met for the permission to stand. Some ask for details to be approved before work starts, such as materials or landscaping; others control how the finished building is used, or remove future permitted development rights. Conditions bind whoever owns the house, so read them before you build.
Pre-application advice: A paid service most councils offer where a planning officer gives a written view on a proposal before an application is made. It is not a decision and does not bind the council, but on a difficult site it shows what the officer will focus on and whether the principle is acceptable. Each council sets its own charges and turnaround times.
Principal designer: A role required on most domestic building projects under the Construction (Design and Management) Regulations and, since 2023, under the Building Regulations too. The principal designer plans and coordinates health and safety and regulatory compliance during the design stage. It is usually the architect, and the appointment should be made in writing.
Prior approval: A light-touch check that applies to some permitted development, such as a larger single-storey rear extension. You notify the council, it consults the neighbours, and it can only consider the specific matters the rules name, such as the effect on neighbours' amenity. If the council does not object within the set period, you can proceed.
Retrofit: Improving the fabric and systems of an existing building so it uses less energy and is more comfortable: insulation, airtightness, better windows, ventilation and then heating. The order matters, because insulating without ventilating causes damp. A whole-house plan, even if carried out in stages, avoids one measure undoing another.
SAP: The Standard Assessment Procedure, the government's method for calculating the energy performance of a home. A SAP calculation is needed to show a new house or a heavily glazed extension meets Part L, and it produces the rating on an Energy Performance Certificate. It is done by an accredited assessor from the drawings and specification.
Section 106 agreement: A legal agreement between a developer and the council, attached to a planning permission, that secures obligations the permission depends on: affordable housing, a contribution to local services, or a restriction on how land is used. Rare on a home extension, more common on a new house, and binding on future owners of the land.
Tender: The stage when a finished set of drawings and a specification go to a shortlist of builders, usually three or four, who each price the same information. Comparing like with like is the point: the lowest figure is not always the best, and a good tender report explains where the prices differ and what has been left out.
Tree Preservation Order (TPO): An order made by a council to protect a particular tree, group or woodland. Pruning or felling a protected tree, or building within reach of its roots, needs the council's consent, and damaging one is an offence. Trees in conservation areas have similar protection by default. Check for orders early, because a tree can decide where an extension goes.

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