Glossary

2

25-degree rule

A daylight check many councils use, taken from BRE daylight guidance. A line is drawn up at 25 degrees from the middle of a neighbour’s lowest main window. If any part of a new building rises above that line, a fuller daylight assessment is usually needed before the design can be judged.

4

45-degree rule

A rule of thumb many councils use to protect light to neighbouring windows. Lines are drawn at 45 degrees from the nearest affected window, on plan, in elevation or both. If the new building crosses them, it may take too much light. Each council words and applies the test in its own way.

A

Abnormal costs

Costs beyond a normal build on a straightforward site, such as deeper foundations on poor ground, long drainage or utility runs, demolition, retaining walls or tree protection. On garden plots, the access drive and services are often the biggest abnormals, and they come straight off what the land is worth.

Appeal

The right to challenge a council that refuses planning permission, imposes conditions you can’t accept, or fails to decide in time. In England appeals go to the Planning Inspectorate; in Wales they go to Planning and Environment Decisions Wales (PEDW). Strict deadlines apply, so check the decision notice straight away.

Article 4 direction

A council order that removes some permitted development rights in a defined area, so works that would normally need no application need planning permission there. It doesn’t change the position for a new separate home, which always needs permission, but it signals that the council guards local character closely.

B

Backland development

Building new homes on land behind existing buildings, usually rear gardens, that has little or no street frontage of its own and is reached by a new or shared access. It differs from infill, which fills a gap along a street frontage, and from tandem development, which is one particular backland layout.

Biodiversity net gain

England’s system requiring many new developments to leave wildlife habitat measurably better than before, assessed using a government metric. There are exemptions and simplified rules for small sites, and the rules have changed over time, so check the current position early. Wales takes a different approach, known as a net benefit for biodiversity.

Build-over agreement

Permission from the water company to build over or close to a public sewer. Public sewers often run through back gardens, so sewer records should be checked early. Some pipes can be built over with an agreement and suitable protection; others have to be diverted or kept clear of the new home altogether.

Building control

The service that checks building work meets the Building Regulations, through plan checks and inspections on site. You can use the council’s building control team or a private building control body. It is separate from planning: a new home needs both planning permission and building control sign-off.

Building line

The line formed by the fronts of buildings along a street. Councils usually expect new homes facing a road to respect it. A backland home sits behind the building line by its nature, which is one reason councils look carefully at how it relates to the houses in front.

Building Regulations

Legal standards for how buildings are constructed, covering structure, fire safety, drainage, insulation, ventilation, access and more. Wales sets several of its own requirements, including sprinklers in every new home. Building Regulations approval is separate from planning permission, and a new home needs both.

C

Character area

Part of a town or village that a council has identified as having a distinct look and feel, for example consistent plot sizes, building styles or a green, spacious setting. It is often described in a character appraisal. New homes there are expected to fit that character, which can shape a backland scheme.

Collaboration agreement

A legal agreement between neighbouring owners who decide to sell or develop their land together. It records how decisions are made, who pays which costs, how proceeds are shared and what happens if someone wants to withdraw. It usually contains an equalisation clause so that value is shared fairly.

Community Infrastructure Levy (CIL)

A charge on new floorspace, including new homes, that helps pay for local infrastructure. It only applies where the council has adopted a charging schedule. A self-build exemption exists, but it must be claimed before work starts on site; claiming after work has begun is too late.

Completion certificate

Confirmation that finished building work meets the Building Regulations. A council building control team issues a completion certificate; a private building control body issues a final certificate. Buyers’ solicitors and mortgage lenders ask for it, so a new home without one can be difficult to sell or mortgage.

Conditional contract

A contract to buy land that only completes if a condition is met. On garden plots the condition is usually the grant of satisfactory planning permission. The price, or the formula for working it out, is fixed at the start. If the condition isn’t met by an agreed long-stop date, the owner keeps the land.

Conservation area

An area of special architectural or historic interest designated by the council. New homes must preserve or enhance its character or appearance, design is scrutinised closely, and work to many trees needs advance notice to the council. Backland schemes are not ruled out, but they need particular care.

Construction management plan

A document explaining how a build will be run safely and considerately: working hours, deliveries, parking for trades, dust and noise control, and keeping the road clear. Councils often require one through a planning condition, particularly where building traffic shares a drive with homes that are lived in.

D

Delegated decision

A planning decision made by a senior council officer under powers delegated by the council, rather than by councillors at a planning committee. Most smaller applications are decided this way. In England, from 31 October 2026, applications for one to nine homes on sites under half a hectare must be. In Wales, depending on the council’s rules, a scheme may go to committee instead if it draws objections or a councillor asks.

E

Easement and right of way

An easement is a legal right over someone else’s land, such as a right to use a driveway or to run pipes and cables. A right of way is the most familiar kind. Land behind houses often depends on these rights, so their exact wording, route and width need checking at the outset.

Ecology survey

A survey by a qualified ecologist to find out which habitats and protected species, such as bats, nesting birds or great crested newts, a site supports. Some surveys can only be carried out at certain times of year, so a council’s request for one can affect the timetable.

Equalisation

A clause, usually in a collaboration agreement, that shares the value of a joint scheme fairly between neighbouring owners, whatever role their land plays. Without it, the owner whose garden provides the access could hold out for more; with it, everyone shares by an agreed formula, often based on land area.

F

Full planning permission

Permission granted on detailed plans showing the layout, scale, appearance, access and landscaping of the new home. It usually comes with conditions, and work must start within the period stated on the decision notice, normally three years in England and five years in Wales. It is the most common route for a single new home in a garden.

G

Garden grabbing

An informal and often critical term for building new homes in back gardens. In England, gardens in built-up areas are not treated as previously developed land. National policy now supports well-designed extra homes in gardens within limits, but councils still refuse schemes that harm the area’s character or neighbours’ living conditions.

H

Heads of terms

A short written summary of the main points of a deal, such as the price or price formula, who pays which costs, any caps, timescales and conditions. It is agreed before solicitors draft the contract. Heads of terms are usually not legally binding, but they set the basis for everything that follows.

Homes for land

An arrangement where an owner provides land and receives one or more of the finished homes in return, instead of all or part of a cash price. For example, a new home might go to a family member. It is usually set up as a form of joint venture, with the details in writing.

I

Infill

Building on a gap in an otherwise continuous built-up frontage, such as a wide side garden or the space between two houses facing the street. Unlike backland development, an infill plot usually has its own frontage and access, which often makes it simpler to get through planning.

J

Joint venture

A partnership in which you provide the land and a developer funds and manages design, planning and building, with both of you sharing the outcome, for example through a share of sale proceeds or a new home. The structure, risks, protections and exit routes should be in writing and checked by your own solicitor.

L

Land promotion

An arrangement where a promoter seeks planning permission on land at its own cost, after which the land is sold and the promoter’s costs and fee come out of the sale proceeds. The owner pays nothing upfront. It is more usual on larger sites, such as several gardens combined, than on single plots.

Land Transaction Tax (LTT)

The tax paid by buyers of land and property in Wales. It replaced Stamp Duty Land Tax there in April 2018 and is collected by the Welsh Revenue Authority. How much is due depends on the deal, so take advice from a tax adviser rather than relying on a general figure.

Listed building

A building of special architectural or historic interest included on the national list. Changes to it need listed building consent, and new development nearby must take account of its setting. A new home in the grounds of, or close to, a listed building needs especially careful design.

Local Development Plan (LDP)

The main planning document for a council area in Wales. It sets out where new homes should go and the policies used to decide applications, and works alongside Planning Policy Wales and the council’s supplementary planning guidance. In England the equivalent document is the Local Plan.

Local Plan

A council’s main planning document in England. It sets out where development should go and the policies used to judge applications, including rules on design, garden land, parking and living conditions. It sits alongside the National Planning Policy Framework. In Wales the equivalent is the Local Development Plan.

M

Material considerations

The matters a council can lawfully weigh when deciding an application, such as overlooking, loss of light, highway safety, parking, design, effects on heritage and wildlife, and previous decisions. Loss of a private view and effects on property value are not normally treated as material considerations.

N

National Planning Policy Framework (NPPF)

The government’s planning policy for England, which councils must take into account when making plans and deciding applications. Among much else, it covers design, housing supply and the approach to garden land, and it makes clear that gardens in built-up areas are not previously developed land.

Net benefit for biodiversity

The Welsh planning requirement, set out in Planning Policy Wales, that development should leave biodiversity better off than before as well as protecting what is already there. It works differently from England’s biodiversity net gain, so ecological advice for a Welsh plot should be tailored to the Welsh rules.

O

Option agreement

A contract giving a buyer the exclusive right, but not the obligation, to buy land within an agreed period, usually once planning permission is secured. The price, or the formula for setting it, is agreed at the start. Terms vary a great deal, so independent legal advice is essential.

Outline planning permission

Permission in principle for a development, with some or all of the detail left for later approval. The details held back, called reserved matters, can include access, appearance, landscaping, layout and scale. Outline can test whether a plot is acceptable before paying for fully detailed designs.

Overage

An agreement that the seller receives an extra payment if the land later becomes worth more than expected, for example if planning is granted for more homes than assumed. It is also called clawback. The trigger, how long it lasts and how the extra value is calculated all need careful drafting.

Overlooking

When windows, balconies or gardens of one home give a direct view into the windows or private garden of another. It is a frequent planning concern on backland plots and is managed through separation distances, careful window placement, obscure glazing, single-storey or roof-lit designs, and planting.

P

Partial release

When a mortgage lender agrees to release part of a mortgaged property, such as a garden plot being sold, from its charge. The plot can’t pass to a buyer free of the mortgage without it. Lenders usually want to see the plan and the price, and may ask for some of the proceeds.

Party wall

Work on a shared wall or boundary, or digging foundations close to a neighbour’s building, can fall under the Party Wall etc. Act 1996, which applies in England and Wales. The person doing the work must serve notice on the neighbour, and surveyors may need to agree a party wall award.

Planning committee

A group of local councillors who decide planning applications at a public meeting, usually larger or contested schemes. In England, small housing schemes of one to nine homes on sites under half a hectare are decided by officers from 31 October 2026. Officers present a report and recommendation, and applicants and objectors can often speak briefly. Councillors can follow or depart from the officer’s advice, but they must give planning reasons.

Planning conditions

Requirements attached to a planning permission, such as approved materials, landscaping, working hours or drainage details. Some must be approved by the council before work starts, known as pre-commencement conditions. Ignoring them can put the permission at risk, so they need tracking carefully from the outset.

Planning Policy Wales (PPW)

The Welsh Government’s national planning policy, which councils in Wales must take into account. It puts strong weight on placemaking, good design and the character of an area, and is supported by Technical Advice Notes such as TAN 12 on design. It is the Welsh counterpart to the NPPF.

Pre-application advice

Feedback from a council’s planning officers on a proposal before a formal application goes in. It can flag problems early and help shape the design. Many councils charge a fee for it, and the advice is informal, so it doesn’t bind the council’s final decision.

Previously developed land

Land that is or was occupied by a permanent structure, often called brownfield land. In England, national policy says private residential gardens in built-up areas are not previously developed land, so garden plots can’t rely on the extra policy support given to building on brownfield sites.

Private Residence Relief

A Capital Gains Tax relief on your main home that can also cover part of a garden sold while you still own and live in the house, generally within a permitted area of up to half a hectare including the house. Selling the garden after the house, or fencing or dividing the land off for development before the sale, can change things, so take advice from a tax adviser.

R

Ransom strip

A strip of land, sometimes only a few centimetres wide, that controls access to a plot. Whoever owns it can refuse access or demand payment for it. Ransom strips are often found along verges, shared drives and old boundaries, so title plans should be checked before any money is spent.

Reserved matters

The details left out of an outline planning permission that must be approved later: access, appearance, landscaping, layout and scale. The application for approval must be made within the time limit set on the outline permission, and the council can still refuse details it finds unacceptable.

Residual valuation

A way of working out what land is worth to a developer. You estimate the value of the finished homes, then subtract build costs, fees, finance, abnormal costs and a reasonable profit. What remains is the land value, which is why access and site costs matter so much on garden plots.

Restrictive covenant

A promise in the title deeds limiting what can be done on land, such as building no more than one house or nothing without consent. Some are old and unenforceable; others still bite. Options include indemnity insurance, agreement with whoever benefits, or an application to the Upper Tribunal (Lands Chamber).

Root protection area

The area around a tree where its roots need protecting during building work, worked out by an arboricultural survey using the British Standard on trees and construction. Building, digging and storing materials inside it are normally avoided, or carefully controlled with special foundations and surfaces.

S

Section 106 agreement

A legal agreement between a council, landowner and developer under section 106 of the Town and Country Planning Act 1990, also called a planning obligation. It can require payments or works that make a scheme acceptable, such as contributions to local services. Many single-home schemes don’t need one, but some do.

Separation distance

The minimum gap a council expects between new and existing homes to protect privacy and light. Many councils use around 21 metres between facing back windows and around 12 to 15 metres between a back window and a blank side wall, but your council’s own guide decides what applies.

Snagging

Finding and fixing small defects at the end of a build, such as doors that stick, paint touch-ups, sealant gaps or minor plaster cracks. A snagging list is usually agreed at handover, and defects that appear later are dealt with under the builder’s and warranty provider’s terms.

Sprinkler system

An automatic fire suppression system that releases water when it detects a fire. Every new house and flat in Wales must have one. In England they aren’t routinely required in a new house, but where a fire engine can’t get close enough, building control and the fire service may agree other measures, often sprinklers. They aren’t an automatic substitute, and some fire services set limits.

Stamp Duty Land Tax (SDLT)

The tax paid by buyers of land and property in England. If you sell part of your garden, the buyer normally pays it rather than you. The amount depends on the price and the type of deal, so take advice from a tax adviser before relying on any figure.

Street scene

How a street looks from the public road: the rhythm of houses and gaps between them, roof lines, boundary walls, hedges and trees. Councils consider whether a new home, or the new drive cut through to reach a backland plot, would harm the street scene.

Structural warranty

Usually a ten-year, insurance-backed warranty covering major defects in the structure of a new home. Most mortgage lenders want one before lending on a new house, though some accept an architect’s or surveyor’s certificate on smaller schemes. It normally has to be arranged before building starts, and the warranty provider inspects the work at stages during the build.

Sustainable drainage (SuDS) and SAB approval

Sustainable drainage systems manage rainwater close to where it falls, using features such as permeable paving, soakaways and rain gardens. In Wales, new building work with a construction area of 100 square metres or more, which includes most single new homes once the drive and site works are counted, needs approval from the council’s SuDS Approval Body (SAB) before construction starts.

T

Tandem development

One house built directly behind another, sharing the same access. It is a common form of backland development on long, narrow gardens. Councils look closely at the noise and disturbance of cars passing the front house, and at privacy between the two homes.

Technical Advice Note 12 (TAN 12)

The Welsh Government’s national guidance on design, which sits alongside Planning Policy Wales. Councils in Wales use it to judge how well a scheme responds to its context, character, access and movement. A backland plot in Wales should show how its design meets these principles.

Title plan

The HM Land Registry plan showing the extent of a registered property, usually edged in red. It shows general boundaries rather than exact legal lines, so a measured survey is still needed. When part of a garden is sold, the new plot gets its own title and title plan.

Transfer of part (TP1)

Selling part of a registered property, such as a garden plot, is a transfer of part, usually made on HM Land Registry form TP1. The plot gets its own title, and the deed sets out the plan, rights of access and services, and any new covenants. A mortgage lender must agree to release the plot.

Tree Preservation Order (TPO)

An order made by the council protecting a specific tree, group of trees or woodland. You need council consent before cutting down, topping, lopping or damaging a protected tree. A TPO doesn’t automatically rule out a backland scheme, but the layout must respect the tree and its roots.

U

Upper Tribunal (Lands Chamber)

The tribunal that can discharge or modify restrictive covenants on land in England and Wales, among other work. Applications can be slow and costly and the result isn’t certain, so this route is usually weighed alongside indemnity insurance or agreement with whoever benefits from the covenant.

Utility connection

Linking a new home to water, sewers, electricity, broadband and gas if used. Each provider quotes separately and lead times vary. On backland plots, the distance back from the road and the route under a shared drive can make connections a significant cost, so they are checked early.

V

Visibility splay

The clear triangle of view a driver needs when pulling out of an access onto a road, kept free of walls, hedges and other obstructions above a set height. The highway authority sets the dimensions, so a narrow access onto a busy road can be the deciding issue for a garden plot.

W

Windfall site

A site for new homes that wasn’t specifically allocated in the council’s plan but comes forward on its own. Many garden plots fall into this category. Councils may expect some windfall sites when planning for housing, but each one is still judged against plan policies.