By the Golbik GBS team · Blog

The first question for almost every extension or loft conversion in London is whether it needs planning permission. The answer depends on the type of property, the size of the project and, very often, the street you live on. This guide explains the national rules and how they play out in the boroughs where we work.

Key takeaways

• Many house extensions and loft conversions can be built under permitted development, without a planning application.
• Permitted development does not apply to flats and maisonettes, and is restricted in conservation areas.
• Article 4 directions can remove permitted development rights on specific streets.
• A Lawful Development Certificate confirms in writing that a project is permitted development.
• Each London borough has its own conservation areas and local guidance, so the same project can be treated differently.

Permitted Development: The National Rules

Permitted development rights allow certain work on houses without a planning application, as long as the conditions are met. The most relevant ones are:

When You Will Need Planning Permission

• The house is in a conservation area and the work affects the roof, front or side.
• An Article 4 direction has removed permitted development rights on your street.
• The property is a flat or maisonette.
• The project goes beyond the limits, such as a wraparound or two-storey extension.
• The building is listed, which also needs listed building consent.
• An earlier planning condition removed permitted development rights.

Planning in the Boroughs We Work In

The national rules are the same everywhere, but conservation areas, Article 4 directions and local design guidance vary from borough to borough:

Planning Is Only One of Three Approvals

• Planning permission or permitted development – what you can build.
• Building Regulations – how it is built: structure, fire safety, insulation, drainage, electrics.
• Party Wall Act – agreement with neighbours for work to shared walls. See our Party Wall guide.

For design options, read our guides to extension types and loft conversion types, or see all the areas we cover.

Frequently Asked Questions

How far can I extend without planning permission in London?

Under permitted development, a single-storey rear extension can go up to 3 metres on a terraced or semi-detached house and 4 metres on a detached house. Through prior approval, this can be up to 6 and 8 metres, subject to the council consulting the neighbours.

Do flats have permitted development rights?

No. Flats and maisonettes do not have householder permitted development rights, so extensions, loft conversions and most external changes to flats need planning permission.

What is an Article 4 direction?

An Article 4 direction is a decision by the council to remove some permitted development rights in a specific area, often in conservation areas. Where one applies, work that would otherwise be permitted needs a planning application.

Is a Lawful Development Certificate compulsory?

It is not compulsory, but it is strongly recommended. It is the council’s formal confirmation that the work is lawful, and buyers’ solicitors often ask for it when you sell.

Not Sure What Applies to Your House?

Golbik GBS builds extensions and loft conversions across London and can help you understand the likely planning route before you commit to a design. Contact us to arrange a survey.

Related Guides

• Full House Refurbishment in London: Stages, Permissions and Timeline
• Loft Conversion Types for London Homes
• Side-Return, Rear or Wraparound Extension?
• Planning a Kitchen Renovation in a London Home
• Bathroom Renovation in London: Wet Rooms, Waterproofing and Safety Zones
• Does Your London Home Need Rewiring?
• Upgrading Heating and Plumbing in an Older London Home
• Party Wall Agreements in London: A Homeowner’s Guide
• Extending a 1930s Semi in Sutton, Wallington and Mitcham
• Consumer Unit (Fuse Box) Upgrades Explained
• Renovating a Victorian Terrace in South West London
• How to Choose a Builder in London

By the Golbik GBS team · Blog

If you live in a London terrace or semi-detached house, almost any loft conversion or extension will affect a wall you share with your neighbour. The Party Wall etc. Act 1996 sets out how that work must be notified and agreed. Getting it right early keeps the project on time and the neighbours on side.

Key takeaways

• The Party Wall etc. Act 1996 applies to most loft conversions and many extensions on terraced and semi-detached houses.
• There are three main notices: party structure (two months), line of junction (one month) and adjacent excavation (one month).
• A neighbour has 14 days to respond; silence counts as a dispute, which is resolved by party wall surveyors.
• Party wall consent is separate from planning permission and Building Regulations.
• Serving notices early and talking to neighbours first is the simplest way to avoid delays.

What Is the Party Wall Act?

The Act gives homeowners the right to carry out certain work to or near a shared wall, and gives neighbours protection while that work is done. It applies in England and Wales to party walls between houses, party structures such as floors between flats, boundary walls and excavation close to a neighbour’s foundations.

The Three Party Wall Notices

Notices must be served on every adjoining owner, which can include a freeholder and long leaseholders of flats next door, not just the person living there.

How the Process Works, Step by Step

1. Talk to your neighbours first. Explain the plans and timetable before anything arrives in writing.
2. Serve the notices. Include a description of the work, drawings where relevant and the proposed start date.
3. Wait for a response. The neighbour has 14 days to consent or dissent.
4. Consent: work can go ahead after the notice period. A schedule of condition of the neighbour’s property is still strongly recommended.
5. Dissent or no reply: surveyors are appointed, either one agreed surveyor or one each, and they prepare a Party Wall award.
6. Work starts in line with the award, and the surveyors deal with any damage claims afterwards.

Which Projects Need a Party Wall Notice?

• Loft conversions – steel beams bearing on the party wall and any raising of the wall. See our guide to loft conversion types.
• Side-return and rear extensions – new walls on the boundary and foundations close to the neighbour. See extension types compared.
• Removing chimney breasts – the chimney stack is usually part of the party structure.
• Underpinning and new foundations near a shared wall.

Minor work such as fixing shelves, re-plastering or rewiring sockets in a party wall does not normally need a notice.

Timing Your Project

Because a party structure notice needs two months, and a dispute adds time for surveyors and the award, it is sensible to serve notices as soon as the design is fixed, in parallel with planning or permitted development checks. Our guide to planning rules by London borough explains that side of the process.

Most of the houses we work on are terraces and semis. Our area guides cover Clapham, Fulham, Chelsea, Hammersmith, Dulwich and Mitcham.

Frequently Asked Questions

Do I need a Party Wall agreement for a loft conversion?

Usually, yes. Most loft conversions on terraced and semi-detached houses involve cutting into the party wall to support new steel beams or raising the wall, which requires a party structure notice at least two months before the work starts.

What happens if my neighbour does not reply to the notice?

If the adjoining owner does not respond within 14 days, a dispute is deemed to have arisen. Each side can appoint a surveyor, or both can agree on one, and the surveyors produce a Party Wall award that sets out how the work will be done.

Who pays for the party wall surveyor?

As a rule, the building owner carrying out the work pays the reasonable costs of the surveyors, including the surveyor appointed by the neighbour.

How long is a Party Wall notice valid?

A notice lapses if the work does not start within 12 months of it being served, so it should be timed with the planned start date.

Is a Party Wall award the same as planning permission?

No. The Party Wall Act deals with the relationship between neighbours. Planning permission or permitted development and Building Regulations approval are separate requirements.

Planning an Extension or Loft Conversion?

Golbik GBS builds loft conversions and house extensions across London and helps clients plan the Party Wall process into the programme from the start. Get in touch to arrange a survey.

Related Guides

• Full House Refurbishment in London: Stages, Permissions and Timeline
• Loft Conversion Types for London Homes
• Side-Return, Rear or Wraparound Extension?
• Planning a Kitchen Renovation in a London Home
• Bathroom Renovation in London: Wet Rooms, Waterproofing and Safety Zones
• Does Your London Home Need Rewiring?
• Upgrading Heating and Plumbing in an Older London Home
• Do You Need Planning Permission? Rules by London Borough
• Extending a 1930s Semi in Sutton, Wallington and Mitcham
• Consumer Unit (Fuse Box) Upgrades Explained
• Renovating a Victorian Terrace in South West London
• How to Choose a Builder in London

By the Golbik GBS team · Blog

For many London families, extending is the best way to gain a large kitchen and living space without moving. The three most common options for terraced and semi-detached houses are the side-return, the rear and the wraparound extension. This guide compares them so you can decide which house extension makes most sense for your home and budget.

Key takeaways

• Side-return extensions fill the narrow passage beside a terrace’s rear outrigger and widen the kitchen.
• Rear extensions push the back of the house into the garden and can often use permitted development.
• Wraparound extensions combine both and add the most ground-floor space, but usually need planning permission.
• Party Wall notices are almost always needed for extensions to terraced and semi-detached houses.
• If a public sewer runs under the extension, a build-over agreement with Thames Water may be required.

Extension Types Compared

Side-return extension

Most Victorian and Edwardian terraces have a narrow outrigger at the back with an awkward passage beside it. Infilling that passage turns a narrow galley kitchen into a wide, bright kitchen-diner. Glazed or sloping roofs with roof lights are often used to bring light into the middle of the house.

Rear extension

A rear extension pushes the back wall into the garden. It is simpler in shape, often possible under permitted development or prior approval, and ideal for creating a family room that opens onto the garden with wide sliding or bi-fold doors.

Wraparound extension

A wraparound combines a side-return with a rear extension. It gives the largest open-plan space and is a popular choice for growing families, but it is the most complex to design and build and usually needs a planning application.

Permitted Development and Prior Approval

• Standard rules: a single-storey rear extension of up to 3 metres for terraced and semi-detached houses and 4 metres for detached houses, with height limits.
• Prior approval: larger single-storey rear extensions of up to 6 or 8 metres, after the council has consulted the neighbours.
• Side extensions: limited to single storey, no wider than half the width of the house, and not permitted in conservation areas.
• Materials: must be similar in appearance to the existing house.
• Not available for flats, and removed in some areas by Article 4 directions.

Conservation areas and local policies vary across London. Our area guides cover Clapham, Fulham, Chelsea, Hammersmith, Dulwich and Mitcham.

Party Walls, Sewers and Building Regulations

• Party Wall Act: notices must be served on neighbours for work to a shared wall, building on the boundary or excavating close to their foundations, usually one to two months before work.
• Build-over agreement: needed from the water company, usually Thames Water, if the extension is built over or close to a public sewer.
• Building Regulations: cover foundations, structure and steel beams, drainage, insulation, glazing, ventilation and fire safety.
• Structural design: opening up the back of the house normally requires steel beams designed by a structural engineer.

Making the Most of the New Space

Most extensions are built around a new kitchen, so it pays to design both together. See our kitchen renovation service, and plan the electrical layout and plumbing and underfloor heating early, before the floor slab is laid.

If you also need extra bedrooms, an extension is often combined with a loft conversion, or with a full refurbishment of the rest of the house.

Frequently Asked Questions

Do I need planning permission for a side-return extension?

Usually, yes. A side extension that also extends beyond the rear wall, or that wraps around, generally falls outside permitted development. A single-storey side extension on its own can sometimes be permitted development, but not in conservation areas.

How far can I extend without planning permission?

Under standard permitted development, a single-storey rear extension can extend up to 3 metres on a terraced or semi-detached house and 4 metres on a detached house. Through the prior approval process, this can be up to 6 and 8 metres respectively, subject to neighbour consultation. These rights do not apply to flats.

What is a build-over agreement?

If your extension will be built over or near a public sewer, the water company needs to approve it before work starts. In most of London this is Thames Water. It protects access to the sewer and avoids costly problems when you sell the house.

Can I live at home while an extension is built?

Many people do, especially for rear extensions where the house can be sealed off from the works. Expect a period without a working kitchen when the new space is joined to the existing house.

Planning an Extension?

Golbik GBS builds rear, side-return and wraparound extensions across London, from foundations and steelwork to glazing, kitchens and finishes. Find out more about our house extension service in London or get in touch to discuss your plans.

Related Guides

• Full House Refurbishment in London: Stages, Permissions and Timeline
• Loft Conversion Types for London Homes
• Planning a Kitchen Renovation in a London Home
• Bathroom Renovation in London: Wet Rooms, Waterproofing and Safety Zones
• Does Your London Home Need Rewiring?
• Upgrading Heating and Plumbing in an Older London Home
• Party Wall Agreements in London: A Homeowner’s Guide
• Do You Need Planning Permission? Rules by London Borough
• Extending a 1930s Semi in Sutton, Wallington and Mitcham
• Consumer Unit (Fuse Box) Upgrades Explained
• Renovating a Victorian Terrace in South West London
• How to Choose a Builder in London

By the Golbik GBS team · Blog

A loft conversion is one of the most effective ways to add a bedroom and bathroom to a London home without losing garden space. The type of conversion you can build depends on your roof, your house and the planning rules on your street. This guide compares the main options so you can see which loft conversion is likely to suit your property.

Key takeaways

• The right loft conversion depends mainly on the shape of your roof and the type of house.
• Rear dormers and L-shaped dormers are the most common choices for London terraces.
• Hip-to-gable conversions suit semi-detached and detached houses with a hipped roof.
• Mansards add the most space but almost always need planning permission.
• Every loft conversion needs Building Regulations approval, including fire safety and a proper staircase.

The Main Types of Loft Conversion Compared

Roof light conversion

Windows are fitted into the existing roof slope and the space is insulated and finished, without changing the roof shape. It is the simplest and least disruptive option, but only works where the loft already has enough head height.

Rear dormer

A box-shaped structure is added to the rear roof slope, creating vertical walls and a flat roof. It is the most common loft conversion in London because it adds useful floor area at a reasonable cost and is often possible under permitted development.

L-shaped dormer

Two dormers are joined: one on the main roof and one on the roof of the rear outrigger. On a Victorian or Edwardian terrace, this typically creates a double bedroom plus a separate bathroom, which is why it is so popular in areas such as Clapham, Fulham and East Dulwich.

Hip-to-gable

The sloping side of a hipped roof is built up into a vertical gable wall, extending the loft sideways. It is often combined with a rear dormer and suits the many 1930s semi-detached houses in outer London.

Mansard

The rear roof slope is replaced with a steep, almost vertical wall with windows set into it, and the roof becomes nearly flat. Mansards give the most space and a traditional appearance, but they change the roofline, so councils usually expect a planning application and look at whether similar extensions exist on the street.

Is Your Loft Suitable?

• Head height: around 2.2 metres from the top of the ceiling joists to the underside of the ridge is a useful rule of thumb.
• Roof structure: traditional timber rafters are easier to convert than modern trussed roofs, which need more structural work.
• Staircase position: a new staircase needs space on the floor below. For loft conversions, Building Regulations accept reduced headroom of 1.9 metres at the centre of the stair and 1.8 metres at the side.
• Chimneys, water tanks and services: these may need to be removed or relocated.

Planning Permission and Permitted Development

Many loft conversions on houses can be built under permitted development, without a planning application, if they meet the conditions. The main ones are:

• Additional roof volume of no more than 40 cubic metres for terraced houses and 50 cubic metres for semi-detached and detached houses.
• No extension on the roof slope facing the highway at the front.
• Materials similar in appearance to the existing house, and no part higher than the existing roof.
• The house is not in a conservation area and permitted development rights have not been removed by an Article 4 direction or an earlier planning condition.

Flats and maisonettes have no permitted development rights, so loft conversions to flats always need planning permission and usually the freeholder’s consent. A Lawful Development Certificate is worth obtaining to confirm a permitted development conversion. If the work involves a shared wall, the Party Wall Act applies too.

Rules vary from borough to borough. Our area guides explain what to expect in Clapham, Fulham, Chelsea, Hammersmith, Dulwich and Mitcham.

Building Regulations for Loft Conversions

Every loft conversion needs Building Regulations approval, whether or not planning permission is required. Building control checks, among other things:

• Structural strength of the new floor, beams and roof.
• Fire safety: a protected escape route, fire doors and interlinked smoke alarms.
• A safe, compliant staircase.
• Insulation and energy efficiency of the new roof and walls.
• Safe electrical work and plumbing for any new bathroom.

A new loft bathroom is a popular addition. See our bathroom renovation service for what this involves. If you also need space downstairs, a loft is often combined with a rear or side-return extension or a full refurbishment.

Frequently Asked Questions

Which loft conversion adds the most space?

A mansard usually adds the most space, because it raises the back slope of the roof to an almost vertical wall along the whole house. An L-shaped dormer over the main roof and the rear outrigger comes close on a typical Victorian terrace.

How much head height do I need for a loft conversion?

As a rule of thumb, around 2.2 metres measured from the top of the ceiling joists to the underside of the ridge gives enough room for a comfortable conversion. Lower lofts can still work, but may need the ceiling below lowered or a design that adds height, such as a mansard.

Do I need planning permission for a dormer loft conversion?

Often not, if the house is outside a conservation area, the dormer is at the rear and the extra volume stays within 40 cubic metres for terraced houses or 50 cubic metres for semi-detached and detached houses. Flats, front dormers, mansards and homes in conservation areas normally need planning permission.

Do loft conversions need fire doors?

In a typical two-storey house, converting the loft creates a third storey, so Building Regulations require a protected escape route, usually fire-resisting doors to the habitable rooms off the staircase, and mains-wired interlinked smoke alarms. An alternative fire strategy, such as sprinklers, may be agreed with building control.

Thinking About a Loft Conversion?

Golbik GBS designs and builds loft conversions across London, managing the structure, staircase, insulation, electrics, plumbing and finishes. Explore our loft conversion service in London or contact us to arrange a survey of your loft.

Related Guides

• Full House Refurbishment in London: Stages, Permissions and Timeline
• Side-Return, Rear or Wraparound Extension?
• Planning a Kitchen Renovation in a London Home
• Bathroom Renovation in London: Wet Rooms, Waterproofing and Safety Zones
• Does Your London Home Need Rewiring?
• Upgrading Heating and Plumbing in an Older London Home
• Party Wall Agreements in London: A Homeowner’s Guide
• Do You Need Planning Permission? Rules by London Borough
• Extending a 1930s Semi in Sutton, Wallington and Mitcham
• Consumer Unit (Fuse Box) Upgrades Explained
• Renovating a Victorian Terrace in South West London
• How to Choose a Builder in London

By the Golbik GBS team · Blog

A full house refurbishment is the most complete kind of renovation: the property is stripped back, its services renewed and its layout improved before everything is finished again. In London, where many homes are Victorian or Edwardian and often sit in conservation areas or leasehold buildings, good planning makes the difference between a smooth project and an expensive one. This guide explains how a full refurbishment in London works, step by step.

Key takeaways

• A full refurbishment usually follows eight stages, from survey and design to snagging and sign-off.
• Internal work in a house rarely needs planning permission, but Building Regulations, the Party Wall Act and, for flats, the freeholder’s consent often apply.
• Electrics, plumbing and heating are renewed during “first fix”, before plastering, so decisions on layout, lighting and kitchens must be made early.
• As a rough guide, flats take two to three months on site and terraced houses four to six months.
• Keep a 10 to 20 percent contingency and collect all compliance certificates at the end.

What Is a Full House Refurbishment?

A full refurbishment covers the whole property rather than a single room. It typically includes stripping out old finishes, structural alterations such as removing walls, renewing the electrical installation, plumbing and heating, re-plastering, new kitchens and bathrooms, flooring, joinery and complete redecoration. It differs from a cosmetic renovation, which refreshes surfaces but leaves the services and layout largely as they are.

For many London homeowners it is the moment to fix everything at once: outdated wiring, inefficient heating, an awkward layout and tired finishes. Doing it in one coordinated project avoids opening up walls and floors twice. You can see what this involves in practice on our full refurbishment service page.

The 8 Stages of a Full Refurbishment

1. Survey and brief

Every project starts with a survey of the property and a clear brief: what you want to change, how you will use each room, your budget and your timescale. For older homes, this is also when hidden issues such as damp, movement or failing services are identified.

2. Design and specification

Layouts, structural changes, lighting, sockets, kitchens, bathrooms and finishes are agreed and written into a specification. The more decisions made at this stage, the more accurate the quote and the fewer costly changes later.

3. Permissions, notices and approvals

Depending on the work, this can include Building Regulations approval, Party Wall notices to neighbours, a licence to alter from your freeholder and, where relevant, planning permission or listed building consent. The table in the next section shows what usually applies.

4. Strip-out and structural work

Old kitchens, bathrooms, flooring and damaged plaster are removed. For homes built before 2000, an asbestos refurbishment survey before strip-out is strongly recommended. Structural alterations, such as removing load-bearing walls with new steel beams, are carried out to an engineer’s design.

5. First fix: electrics, plumbing and heating

With walls and floors open, new cables, pipework, drainage and heating are installed. This is the stage when the electrical installation is rewired and the plumbing and heating system renewed, so positions for sockets, lights, radiators and appliances need to be final.

6. Plastering, insulation and joinery

Walls and ceilings are plastered or boarded, insulation and soundproofing added where needed, and joinery such as door linings, skirting and staircases repaired or replaced.

7. Second fix, kitchens and bathrooms

Sockets, switches, lights, radiators and sanitaryware are connected, and the kitchen and bathrooms are installed, tiled and finished.

8. Decoration, snagging and sign-off

Flooring and decoration complete the work. A final walk-through produces a snagging list of small defects to be put right, and the compliance certificates are handed over.

Which Permissions and Certificates Do You Need?

Permissions depend on what you change and on the type of property. This overview covers the most common situations in London:

If the refurbishment also adds space, see our guides to house extensions and loft conversions. For domestic projects, the Construction (Design and Management) Regulations 2015 normally pass the client’s health and safety duties to the contractor.

How Long Does a Full Refurbishment Take?

The time on site depends on the size of the property, the amount of structural work and how quickly decisions are made. As a rough guide:

• One- or two-bedroom flat: around two to three months on site.
• Three- or four-bedroom terraced house: around four to six months on site.
• With an extension or loft conversion: add several months, depending on the design.

Before work starts, allow time for design, Party Wall agreements, freeholder consent and the lead time of bespoke items. Changes to the specification once work has started are the most common cause of delay.

Refurbishing a Period Property in London

Most London refurbishments involve Victorian or Edwardian houses, or flats converted from them. These buildings bring particular considerations: original features worth keeping, older wiring and lead or iron pipework, suspended timber floors, lime plaster and, in many streets, conservation area rules on windows and front elevations.

Local rules vary by borough. Our area guides explain what to expect in Clapham, Fulham, Chelsea, Hammersmith, Dulwich and Mitcham.

Budgeting and Living Arrangements

• Fix the specification first. A detailed specification gives comparable quotes and fewer surprises.
• Keep a contingency. Many professionals recommend 10 to 20 percent of the build cost, towards the upper end for older homes.
• Check the VAT position. Renovation work is normally standard-rated, but a reduced 5 percent rate can apply to homes that have been empty for at least two years. Confirm with HMRC or an accountant.
• Plan where you will live. For a full refurbishment, moving out is usually faster, cheaper and far more comfortable than living on site.
• Use one contractor to coordinate. A single point of contact for all trades reduces gaps between stages and responsibility disputes.

Frequently Asked Questions

How long does a full house refurbishment take in London?

As a rough guide, a full refurbishment of a two-bedroom flat often takes around two to three months on site, and a three- or four-bedroom terraced house around four to six months. Design, approvals and lead times for items such as kitchens and windows come on top, and extensions or loft conversions add further time.

Do I need planning permission for a full refurbishment?

Not usually for internal work in a house. Planning permission is typically needed for extensions beyond permitted development, external changes in conservation areas, changes to flats, and any work to listed buildings, which also needs listed building consent. Building Regulations apply to most structural, electrical, drainage and heating work either way.

Can I live in my home during a full refurbishment?

It is possible for some phased projects, but for a genuine full refurbishment most people move out. The kitchen, bathroom, heating and power are disconnected for long periods, and the work moves faster and costs less when the trades have the whole property.

What certificates should I receive at the end?

Typically a Building Regulations completion certificate for notifiable work, an Electrical Installation Certificate for new wiring, a Gas Safe certificate for gas and boiler work, and FENSA or equivalent certificates for replacement windows. Keep them safe, as buyers and their solicitors will ask for them.

How much contingency should I allow?

Many professionals recommend keeping 10 to 20 percent of the build cost in reserve, towards the upper end for older London properties, where hidden issues such as damp, rotten joists or outdated wiring are common.

Planning a Full Refurbishment?

Golbik GBS manages full refurbishments of houses and flats across London, coordinating every trade from strip-out to final decoration. Find out more about our full refurbishment service in London or get in touch to arrange a consultation.

Related Guides

• Loft Conversion Types for London Homes
• Side-Return, Rear or Wraparound Extension?
• Planning a Kitchen Renovation in a London Home
• Bathroom Renovation in London: Wet Rooms, Waterproofing and Safety Zones
• Does Your London Home Need Rewiring?
• Upgrading Heating and Plumbing in an Older London Home
• Party Wall Agreements in London: A Homeowner’s Guide
• Do You Need Planning Permission? Rules by London Borough
• Extending a 1930s Semi in Sutton, Wallington and Mitcham
• Consumer Unit (Fuse Box) Upgrades Explained
• Renovating a Victorian Terrace in South West London
• How to Choose a Builder in London