The Ultimate Guide to Home Extensions in Brighton and Hove
Everything you need to plan a home extension in Brighton and Hove — the types of extension available, planning and Building Regulations, structural and traditional-construction considerations, costs, timelines, and how to choose a builder suited to older and coastal properties.
Introduction
Extending a home is one of the most significant decisions a property owner in Brighton and Hove can make. Done well, it adds genuinely useful space and improves the way a property works for the people living in it. Done poorly, it creates problems that can be expensive to put right.
Brighton and Hove present particular considerations. The housing stock ranges from Regency and Victorian terraces to Edwardian villas, 1930s semis and modern developments, with a significant amount of traditional solid-wall construction including bungaroosh. Many properties sit within conservation areas or are listed. Coastal exposure and varied ground conditions add further factors.
This guide sets out the full picture so owners can approach an extension with realistic expectations and an understanding of the decisions involved.
Why Extend in Brighton and Hove
For many owners, extending is preferable to moving. It avoids the cost and disruption of a sale and purchase, and it lets you tailor the space to how you actually live.
Common reasons to extend include:
- Adding a ground-floor living space or kitchen-diner
- Creating an extra bedroom
- Adding a bathroom or en-suite
- Improving the flow between house and garden
- Accommodating a growing family without moving
- Adding a home office or utility space
The best extension responds to a genuine need rather than simply adding volume for its own sake.
Types of Extension
Extensions vary in form, size and complexity. The right type depends on the property, the need, the budget and the planning constraints.
Common extension types in Brighton and Hove include:
- Single-storey rear extension
- Two-storey rear extension
- Side return extension (common on Victorian terraces)
- Side extension
- Wrap-around extension
- Loft conversion
- Basement or cellar conversion
- Garage conversion
- Front porch extension
- First-floor extension over an existing structure
Each has different planning, structural and cost implications.
Single-Storey Rear Extensions
Single-storey rear extensions are among the most common in Brighton and Hove. They typically add kitchen-diners, living space or garden rooms at the back of the property.
They are often within permitted development where they meet the size limits, but two-storey neighbours, conservation-area status or previous extensions can change that.
Key considerations include:
- Fenestration and natural light
- Connection to the garden
- Roof form — flat, pitched or lantern
- Impact on neighbouring amenity and overlooking
- Drainage and services rerouting
- Foundations and ground conditions
The quality of the design and detailing matters more than the size of the addition.
Side Return Extensions
Many Brighton and Hove Victorian terraces have a side return — a narrow passage between the house and the boundary. Extending into the side return reclaims that space and is a popular way to enlarge a kitchen.
Side returns almost always involve the boundary wall, drainage runs and party-wall considerations, so they need careful design and party-wall agreement.
Typical issues include:
- Party Wall etc. Act 1996 procedures
- Boundary wall ownership and rebuilding
- Rerouting of drainage and services
- Loss of a side passage and its access
- Light to neighbouring windows
- Foundations adjacent to the boundary
A side return is a small extension that can involve a disproportionate amount of coordination.
Two-Storey Extensions
A two-storey extension adds space on two levels — often a larger ground-floor room below and a bedroom or bathroom above.
Two-storey extensions are more likely to require planning permission and have greater structural implications than single-storey work.
Considerations include:
- Planning permission requirements
- Impact on neighbouring amenity
- Foundations for the additional load
- Structural design for two storeys
- Staircase and means of escape
- Window placement and overlooking
- Integration of new and existing rooflines
The junction between the new structure and the existing building is particularly important structurally and visually.
Loft Conversions
Loft conversions add habitable space within the existing building envelope, often without the footprint implications of a ground-floor extension.
They are popular in Brighton and Hove terraces and villas, but the structure, stairs and headroom need careful assessment.
Key considerations include:
- Existing roof structure and its capacity
- Headroom for a habitable room
- Staircase location and design
- Means of escape and fire safety
- Dormer design and planning constraints
- Party wall implications in terraces
Not every loft is suitable for conversion; the existing structure has to be able to take the new floor loading and provide adequate headroom.
Basement and Cellar Conversions
Some Brighton and Hove properties have existing cellars that can be converted into usable space. A few properties consider new basement excavation.
Cellar conversion is very different from new basement construction, and both have significant structural, waterproofing and drainage implications.
Considerations include:
- Existing headroom
- Tank or waterproofing system
- Groundwater and drainage
- Structural alterations to existing walls and floor
- Ventilation and means of escape
- Impact on party walls and neighbours
- Listed building and conservation constraints
Basement work is among the most technically demanding residential projects and benefits from specialist input.
Garage Conversions
Converting an integral or attached garage is a relatively cost-effective way to add a room. Many Brighton and Hove homes have garages that are too small for modern cars but perfectly serviceable as internal space.
Key considerations include:
- Planning permission and permitted development
- Building Regulations for habitable use
- Insulation and thermal performance
- Structural alteration of the garage front
- Services — power, water, drainage, heating
- Integration with the existing house layout
Garage conversions are covered in detail in our dedicated garage conversions guide.
Planning Permission
Planning permission governs whether you can build at all and what you can build. It is separate from Building Regulations, which govern how the building work is constructed.
Many single-storey rear extensions fall within permitted development, but the rules have limits and exceptions, and they do not apply to listed buildings.
Planning permission is more likely to be required for:
- Side extensions
- Two-storey extensions
- Extensions in conservation areas
- Work to listed buildings
- Extensions exceeding permitted development limits
- Properties that have already used their permitted development
Permitted development should be confirmed — not assumed — for each property, and many owners obtain a Lawful Development Certificate for certainty.
Building Regulations
Building Regulations apply to almost all extension work. They govern the construction — structure, fire safety, thermal performance, ventilation, drainage, electrical safety and accessibility.
Building Regulations approval is separate from planning permission, and both may be required for the same project.
Building Regulations cover:
- Structural design and calculations
- Foundations
- Thermal insulation and energy efficiency
- Ventilation
- Fire safety and means of escape
- Drainage
- Electrical installation
- Accessibility
The building control process involves plan checks and site inspections at key stages of the work.
The Party Wall etc. Act 1996
Where an extension involves work on or near a boundary, or work to a shared wall, the Party Wall etc. Act 1996 usually applies.
The Act requires notice to be given to adjoining owners, and they may dissent and require a party-wall surveyor to agree the works.
Work commonly covered includes:
- Side return extensions on a boundary
- Loft conversions in terraces
- Basement work
- Underpinning near a boundary
- Cutting into a party wall
- Building a new wall up to or on the boundary
Party-wall matters should be started early, as they can introduce delay if neighbours dissent.
Structural Considerations
Extensions almost always require structural design. The foundations, any steelwork, the roof structure and the connection to the existing building are all structural elements.
A structural engineer designs and certifies these elements, and their calculations are submitted for Building Regulations approval.
Structural issues to consider include:
- Existing foundation depth and condition
- Ground conditions on the site
- Load paths through the existing building
- New openings in existing walls
- Steel beams and columns
- Roof structure and load transfer
- Connection of new and existing structures
On older buildings, the engineer needs to be familiar with traditional construction.
Traditional Brighton Construction
Much of Brighton and Hove's housing stock is of traditional solid-wall construction. Bungaroosh, solid brick and flint walls behave differently from modern cavity construction and require compatible approaches.
Where an extension meets a traditional wall, the junction needs particular attention to avoid moisture and movement problems.
Considerations for older buildings include:
- Compatibility of new and existing materials
- Moisture management at the junction
- Avoiding cement-based materials where lime is appropriate
- Differential movement between new and old
- Existing wall condition and repair before connection
- Listed building and conservation constraints
Applying modern detailing uncritically to a traditional building can create moisture and structural problems.
Conservation Areas and Listed Buildings
Large parts of Brighton and Hove are within conservation areas, and many individual buildings are listed. Both statuses impose additional controls.
Listed building consent is required for any alteration that affects the character of a listed building, including internal work. Conservation area consent applies to demolition, and normal planning rules are applied more strictly.
Implications include:
- Stricter controls on external appearance
- Controls on materials and detailing
- Possible restrictions on extensions altogether
- Longer determination periods
- Need for sympathetic design
An extension to a listed building should be designed with the building's significance in mind, not against it.
Foundations and Ground Conditions
Brighton and Hove sit on varied geology — chalk, clay, sands and made ground. Ground conditions affect foundation design and cost.
Existing foundations on older buildings may be shallow, and new foundations adjacent to them need to avoid undermining the existing structure.
Foundation considerations include:
- Existing foundation depth and construction
- Ground-bearing capacity
- Trees and shrinkable clays
- Proximity to existing foundations
- Underpinning where required
- Cost implications of poor ground
Foundation design is one of the biggest variables in extension cost, and it is not always known until the work begins.
Design and Architecture
Good design is what makes an extension successful. It is not only about appearance — it is about how the space works, how light enters, how the building is used, and how it relates to its setting.
In Brighton and Hove, extensions range from sympathetic period-style additions to contemporary contrast designs. Both can work; both can fail. The quality of the design and detailing is what matters.
Design considerations include:
- Relationship to the existing building
- Natural light and orientation
- Flow between old and new
- Scale and proportion
- Roof form
- Materials and detailing
- Impact on the street and neighbours
A good architect or designer is as important as a good builder.
Services and Utilities
Extensions usually involve new or rerouted services — drainage, water, electricity, heating and sometimes gas.
Existing drainage runs, particularly on older terraces, may need rerouting, and manholes may need to be relocated or built over with the agreement of the building control and the water company.
Services to consider include:
- Drainage and soil pipes
- Water supply
- Electrical supply and distribution
- Heating and radiators or underfloor heating
- Ventilation
- Data and communications
Services are often the source of unforeseen cost on older properties.
Thermal Performance and Energy Efficiency
New extensions must meet current Building Regulations for thermal performance. The existing building they connect to usually does not, so the junction between the two needs careful detailing to manage heat loss and condensation.
On older solid-wall buildings, over-insulation or the wrong insulation can create interstitial condensation, so the approach needs to be compatible with the existing construction.
Thermal considerations include:
- Wall, roof and floor insulation
- Window specification
- Heating system sizing
- Ventilation strategy
- Thermal bridging at junctions
- Compatibility with traditional construction
Energy efficiency and breathability are not always in conflict, but they have to be balanced on older buildings.
Costs and Budgeting
Extension costs vary widely with size, type, specification, ground conditions and the extent of structural work. Setting a realistic budget early prevents a project stalling partway through.
Cost is driven by more than floor area. Structural complexity, ground conditions, the level of finish and the amount of alteration to the existing building all affect the total.
Budgeting should account for:
- Design and professional fees
- Planning and Building Regulations fees
- Party-wall surveyor fees where required
- Structural engineer fees
- Construction cost
- Contingency for unforeseen work
- VAT
A contingency of at least 10–15% is prudent on older properties, where unforeseen issues are common.
Timelines
An extension project has several stages, each with its own timescale. The construction phase is often shorter than the design, planning and approvals that precede it.
A typical sequence includes:
- Brief and design
- Planning application (around 8 weeks determination)
- Building Regulations application
- Party-wall notices and agreements
- Tender and contractor selection
- Construction
- Snagging and completion
Planning determination alone is typically around eight weeks, and delays at any stage can extend the overall programme.
Choosing a Builder
The builder is the single most important choice after the design. The quality of the build, the management of the site and the handling of unforeseen issues all rest with the builder.
For older and traditional Brighton and Hove buildings, a builder familiar with that construction is worth more than one who is not.
When choosing a builder, consider:
- Experience with the type of project
- Experience with traditional construction
- References and previous work
- Insurance and warranties
- Clarity of quotation and contract
- Site management and communication
- Understanding of Building Regulations and listed-building requirements
The lowest price is rarely the best value on a complex extension.
How Safe-Bricks Approaches Extensions
Safe-Bricks is a building contractor specialising in older and traditional Brighton and Hove properties, including bungaroosh, solid brick and flint construction.
On extension projects we work alongside the structural engineer and, where required, the architect, and we coordinate the structural design with the building work.
Our approach includes:
- Assessment of the existing building before work begins
- Coordination with structural engineer and architect
- Compatible materials for traditional construction
- Careful junctions between new and existing work
- Building Regulations compliance throughout
- Clear communication during construction
The aim is an extension that is structurally sound, buildable and sympathetic to the existing building.
Planning an Extension? Start With Photographs
If you are considering an extension, the most straightforward first step is to send Safe-Bricks photographs of the property and the area you are considering extending.
From photographs we can give an initial view on the likely planning and structural considerations, the compatibility with the existing building, and the appropriate next steps.
Useful information includes:
- Photographs of the property and the proposed area
- The age and type of property where known
- What you want to achieve
- Any existing defects or issues
- Whether the property is listed or in a conservation area
From there we can advise on whether design, planning or structural input is needed before any construction begins.
Home extension frequently asked questions
Not sure where to start?
Send us photographs of the area of concern. It is the most straightforward first step — we will look at what you can see and advise on the appropriate next steps.