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    Permitted Development Rules: What You Can Build Without Planning Permission

    Single-storey extension at a UK home

    Permitted development rights let you make certain changes to a house, such as a single-storey rear extension or a garden outbuilding, without applying for planning permission, as long as you stay within set limits and conditions. In England the detailed rules sit in the government’s technical guidance for householders, and the rights can be restricted or removed on some properties. Check this before you offer on a house that has been extended, or on one you are counting on extending.

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    Key points

    • Permitted development (PD) is a national grant of planning permission for specified works, within limits on size, height, position and use.
    • A single-storey rear extension can usually go out 3 metres (4 metres if detached) under the standard rule. Larger limits of 6 and 8 metres need the neighbour consultation and prior approval process.
    • Outbuildings within 2 metres of a boundary cannot be taller than 2.5 metres, and must not sit forward of the front wall of the house.
    • Conservation areas, other Article 2(3) land and local council conditions can remove or reduce your rights, so check before you buy.
    • Your plans also have to be financeable: lenders look at loan-to-value (LTV) and your income, not just the price.

    Table of Contents

    What is permitted development, and how does it differ from planning permission?

    Planning permission is something you apply for and the local planning authority decides. Permitted development is a statutory permission already granted nationally for specific types of work. The government guidance describes it as allowing householders to make certain enlargements, improvements, alterations and additions to a house and its surrounding area without a planning application, subject to the limits and conditions in the 2015 Order.

    The practical differences are these:

    • No application fee or decision period for the standard rights. You build if your plans meet every limit and condition.
    • Limits are strict. If one measurement is over, the whole scheme usually needs a planning application.
    • Other consents still apply. Building Regulations, party wall matters and, for leasehold homes, your lease terms are separate from planning.
    • Rights can be taken away. The council can restrict them, and some locations never had them in full.

    The technical guidance linked above is written for England. Wales, Scotland and Northern Ireland have their own planning rules and householder allowances, so if the property is outside England, check with the local planning authority rather than assuming the figures below apply.

    Do you have permitted development rights on your property?

    Not every home has the full set. Rights can be restricted or removed by planning constraints such as conservation areas, other Article 2(3) land, or conditions the council has attached, including on estates where an earlier planning permission removed them. Flats and maisonettes do not have the same householder rights as houses, and the guidance is aimed at houses.

    There are three quick checks before you rely on PD:

    1. Find the location constraints. Is the property in a conservation area or another designated area? Our guide on how to check if a property is in a conservation area walks through it.
    2. Look at the planning history. The council’s online planning register shows past permissions and any condition removing rights.
    3. Ask the council. A lawful development certificate confirms in writing that a proposed or existing use or building work is lawful. It is worth having for work you are about to rely on when buying or selling.

    If you are buying, ask the seller’s solicitor early. Your conveyancer will check the paperwork, but they can only check what they are given, so raise any extension or outbuilding you can see in the photos.

    How big can an extension be under permitted development?

    The figures below come from the government’s householder technical guidance for England and apply to a house that has not already used up its allowance.

    Work Standard limit Larger limit (with prior approval)
    Single-storey rear extension, detached house Up to 4 metres from the rear wall Up to 8 metres
    Single-storey rear extension, any other house Up to 3 metres from the rear wall Up to 6 metres
    Height of a single-storey rear extension Must not exceed 4 metres Must not exceed 4 metres
    Total built coverage Buildings other than the original house must not cover more than 50% of the curtilage Same

    The guidance says the larger 6 and 8 metre extensions are only available if the house is not on Article 2(3) land (conservation areas are the common example) or a Site of Special Scientific Interest. They also require the neighbour consultation process, and the local planning authority must give prior approval. Neighbours can object, and the council weighs the effect on their amenity.

    What the “original house” means for your limits

    Limits are measured against the house as it stood on 1 July 1948, or as first built if it was built after that. An extension added by a previous owner can therefore use up part of your allowance. This matters when you buy: a house that already has a large rear extension may have little or nothing left for you to add. Compare the floor plan in the listing with what is on the planning register, and look for any extension built without evidence of permission or a certificate.

    Worked example: a semi-detached house

    Take a semi-detached house with a rear garden, outside a conservation area. The standard allowance is a single-storey extension projecting up to 3 metres. The larger 6 metre option exists in principle, but you would go through neighbour consultation and prior approval, and the neighbours’ response can shape the outcome. If the garden is small, the 50% coverage limit may constrain you before the depth limit does. Add up everything already in the garden, including sheds and previous additions, before you assume the full depth is available.

    Extension depth and garden coverage limits

    What is the 2.5 metre rule?

    The 2.5 metre rule applies mainly to outbuildings. If any part of a building is within 2 metres of the boundary of the property, its total height must not exceed 2.5 metres to fall within permitted development. The government guidance says the height is measured from the highest ground level immediately next to the building up to its highest point. On a sloping garden that can catch people out, because the measurement is taken from the highest adjoining ground.

    The other core conditions for outbuildings in England, from the guidance and from council advice such as St Albans City and District Council, include that the building must not be forward of the front wall of the house. Outbuildings must also be for purposes incidental to the enjoyment of the house, such as a store, a home office, a gym or a summerhouse. They are not for use as a separate home.

    If you are planning something larger or more elaborate, such as an outdoor kitchen or bar, the same height and coverage limits apply. Design ideas like these garden bar ideas are useful to read alongside the rules, because the footprint and height you choose determine whether it stays within permitted development.

    What is the 2.5 metre rule?

    Does permitted development mean you can skip Building Regulations?

    No. Permitted development deals with planning only. A rear extension that needs no planning application will normally still need Building Regulations approval for structure, insulation, fire safety, drainage and electrics. Building Control sign-off also matters when you sell, because the buyer’s solicitor will ask for the completion certificate.

    The same goes for party wall matters if you build on or near a boundary. Neither planning nor Building Regulations replaces your obligations to neighbours or any restrictive covenants in the title deeds, which are a private legal matter between landowners.

    How does permitted development differ from a planning application in practice?

    • Certainty. PD is certain only if you meet every limit. Planning permission gives you a decision from the council tailored to your design.
    • Flexibility. If your design exceeds the limits by even a small margin, you need an application. Applications can allow bigger, taller or differently shaped additions where the council agrees.
    • Neighbours. Standard PD involves no consultation. Larger rear extensions and applications both involve neighbours, but through different processes.
    • Evidence. A planning permission is a document you can hand to a buyer. For PD, a lawful development certificate does the same job.

    If your plan fits within the limits, PD is often the simpler route. If it does not, a planning application is not a failure, it is the right route for that design.

    What is the four-year rule for planning?

    The four-year figure is commonly cited for building works that were completed without permission: after a set period, the council may no longer be able to take enforcement action. A longer period, commonly cited as ten years, applies to a material change of use. The exact position depends on the specific breach, and retrospective rights cannot be claimed where the development did not meet the criteria in the first place.

    For a buyer this is a matter for your solicitor, not something to rely on yourself. If an extension looks unauthorised, ask for the evidence: planning permission, a lawful development certificate, or Building Regulations completion. Without paperwork you may face difficulties at resale, and some lenders will ask questions.

    What are the 2026 planning changes?

    Planning rules in England have been under regular review, and permitted development allowances have been amended several times since the 2015 Order. Because this changes, treat any figure in an article as a snapshot and confirm it on the government’s current Planning Portal or GOV.UK guidance before committing to a design. The technical guidance cited here is dated 10 September 2019 on its page, so check for later amendments. If you are buying a property specifically for its development potential, ask your architect or planning consultant to confirm the rules that apply on the day you submit.

    Why should you check permitted development before you make an offer?

    Extension potential has a value, but only if the rights exist. When you offer, the question is not just “what are similar homes selling for” but “is the improvement I am paying for actually possible”. A house that looks like it could take a 4 metre kitchen extension might be in a conservation area, or might have had its rights removed.

    The homes that sold on the same road tell you what extended and unextended versions achieve. A data-led report such as our buyer report compares recent sales, including those on the same road, alongside area data, which helps you see whether paying for potential is justified. It is a guide to what to offer, not a RICS valuation or a survey, and you should still use a surveyor and a solicitor.

    Flood risk and local constraints sit alongside planning. See our guide on how to check flood risk before buying, since a flood-risk area can affect both what you can build and what insurers and lenders will accept.

    What is LTV on a mortgage, and why does it matter if you plan to extend?

    Loan-to-value is the size of your mortgage as a percentage of the property’s value. The legal definition in the Mortgage Credit Directive Order describes it as the outstanding credit under all relevant mortgage contracts on the same land, immediately after the last credit is provided, as a percentage of the land value as assessed by the lender.

    A simple illustration with made-up numbers: if a lender values a house at £300,000 and you borrow £270,000, your LTV is 90% and your deposit is 10%. A 75% LTV on the same house would mean borrowing £225,000. Lower LTV generally gives you access to a wider choice of deals, and the lender’s valuation, not your offer price, is what counts.

    That is why a house that needs work can be harder to finance. If the lender values it below your offer, the LTV rises and you may need a bigger deposit. “90 LTV” simply means a 90% loan against a 10% deposit.

    There are government-backed routes at higher LTVs. The mortgage guarantee scheme described by MoneyHelper guarantees lenders on capital-repayment mortgages for first-time buyers and home movers buying their main home, with LTVs of 90% to 95%. Availability depends on the lender, so ask a broker or lender directly.

    The lender also needs to be comfortable with any building work. If you plan to extend after buying, tell your broker at the start, because it can affect the product and whether you borrow extra later. Our mortgage calculator helps you test monthly repayments at different LTVs.

    How many times your salary can you borrow for a mortgage in the UK?

    There is no single legal multiple. Lenders set their own affordability rules. Following Bank of England recommendations, the government said in July 2025 that more mortgages will be available at over 4.5 times a buyer’s income, and that some lenders, Nationwide among them, have lowered the salary thresholds for higher loan-to-income lending.

    To illustrate with invented numbers: on a £50,000 household income, 4.5 times is £225,000. A lender may offer less once it looks at your outgoings, debts and credit history. Mortgage lenders consider both the total you could borrow and whether the monthly payments are affordable given your income and current outgoings. The government’s guidance advises you to check your credit score, assess your income and outgoings, and include all debt repayments before applying.

    Your credit report lists accounts, amounts owed and repayment behaviour, and lenders use that history to assess risk, which can affect both interest rates and how much they will lend. For the detail of how the sums work, see our guide to how mortgage affordability is calculated.

    Does the same apply to buy-to-let?

    Not quite. For a buy-to-let mortgage the lender also looks at the interest coverage ratio: expected monthly rent divided by monthly interest payments, as defined in legislation. If you are a landlord planning to add a bedroom under permitted development, the rent the extra space could earn and the lender’s view of it both matter. Our comparison of HMO versus single let covers how the strategies differ.

    Should you use a mortgage adviser?

    If your plans involve works, a low deposit or self-employed income, an adviser can match you to lenders whose criteria fit. MoneyHelper explains that advisers help identify suitable products and provide an illustration setting out fees, charges and repayments. It also advises comparing deals by total cost over the full term, including fees and interest, not just the initial rate.

    What we think about permitted development and offers

    Buyers tend to treat planning potential as a bonus, when it is often the largest single swing in what a house is worth to them. We think the right order is: confirm the rights exist, confirm the lender and your budget can support the work, then decide your offer using evidence from the same road.

    That is the thinking behind Offer Smart. We bring together comparable sold prices, area risk such as flood and crime, local amenities and running costs in one report, so you can weigh up a house on its facts rather than on a listing’s description. Our reports are a data-led guide to what to offer. They are not a RICS valuation, a survey or financial advice, and we would always want you to use a surveyor and conveyancer alongside them.

    For estate agents, we think the same evidence belongs in front of buyers earlier. Branded property and area guides covering schools, broadband, bills and council tax mean fewer surprises after an offer is accepted.

    Rhys Hedges

    Where can you check a property before you offer?

    If you are comparing a few houses and want the evidence in one place, our full buyer report costs £19.99 as a one-off. It analyses a UK address or a Rightmove or OnTheMarket link, covering comparable sales, area data, risk and running costs. If you are viewing many homes, the Unlimited Homebuyer Membership is £39.99 per month.

    Offer Smart

    You can see what a report contains in the example buyer report before you buy. Estate and letting agents can look at the agent plans for branded guides.

    A short checklist before you rely on permitted development

    1. Confirm the property is a house, not a flat or maisonette.
    2. Check for conservation area, other Article 2(3) land or SSSI status.
    3. Read the planning history for conditions that remove rights.
    4. Measure the original house and add up all existing extensions and outbuildings.
    5. Check depth, height, distance from boundaries and the 50% curtilage limit.
    6. Allow for Building Regulations and, where relevant, the party wall process.
    7. Ask for a lawful development certificate if you need certainty for a sale or loan.
    8. Speak to a mortgage broker about LTV and income before you commit.

    FAQ

    Can I build a bigger extension than the standard limit under permitted development?

    In England you may be able to go to 8 metres for a detached house or 6 metres for any other house on a single storey. That is only if the house is not on Article 2(3) land or an SSSI, and the neighbour consultation and prior approval process is followed. Otherwise you need a planning application.

    Does a conservation area remove permitted development rights?

    Conservation areas are one of the planning constraints that can restrict or remove rights, and the larger rear extension option is not available there. Rules differ by location, so confirm with the local planning authority before you design anything.

    What does 90 LTV mean on a mortgage?

    It means the loan is 90% of the lender’s valuation of the property and your deposit covers the other 10%. On a £300,000 valuation that is £270,000 borrowed, as an illustration. Lower LTVs typically open up a wider range of deals.

    How many times my salary can I borrow?

    Lenders set their own limits, and there is no fixed national multiple. Following Bank of England recommendations, more mortgages are available above 4.5 times income, but your outgoings, debts and credit history decide what a lender will actually offer.

    Sources

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