If you love your home but simply need more space, a single storey extension might be the perfect solution. Whether it’s a bigger kitchen, a brighter living area or a home office that finally gets you off the dining table, extending outwards gives you the extra room without the cost and stress of moving house. This guide reveals what single storey extensions really cost in 2025, which types deliver the best value, and the honest drawbacks you need to consider before building.

Key topics covered:

  • Actual 2025 costs per square metre and total project prices
  • Permitted development rules and when you need planning permission
  • How much value single storey extensions add to your property
  • Different extension types and which works best for your home
  • Real drawbacks that affect garden space and family life
  • Features that deliver proper returns on investment
  • How location and property type affect your extension costs

What Does a Single Storey Extension Actually Cost in 2025?

Costs vary dramatically depending on location, size, materials and design complexity. Based on 2025 UK industry data, expect to pay between £1,200 and £3,500 per square metre for a single storey extension.

Breaking this down by quality level:

  • Budget extensions: £1,200-£1,800 per square metre (basic materials, simple design)
  • Mid-range extensions: £1,800-£2,500 per square metre (good quality materials, standard features)
  • Premium extensions: £2,500-£3,500 per square metre (high-end materials, bespoke features, London/South East)

For a typical 30 square metre extension, this translates to:

  • Budget: £36,000-£54,000
  • Mid-range: £54,000-£75,000
  • Premium: £75,000-£105,000

These figures exclude VAT at 20%, which adds another £7,200-£21,000 to your total cost. They also exclude professional fees for architects, structural engineers and planning applications, which typically add 10-15% to the build cost.

In Mansfield, Nottinghamshire, South Yorkshire and Derbyshire, most single storey extensions fall into the £40,000-£70,000 range including VAT for a 25-30 square metre extension with good quality materials and finishes.

What Affects Single Storey Extension Costs?

Several factors push costs up or down:

Size matters: Smaller extensions under 20 square metres often cost more per square metre because fixed costs like foundations and connections get spread over less space.

Materials and finishes: Basic brick and render with standard windows costs far less than matching heritage materials or installing premium bi-fold doors.

Groundwork complexity: Sloping sites, poor drainage or difficult soil conditions increase foundation costs significantly.

Access issues: Narrow side passages or restricted parking that make it hard to get materials and equipment to site add time and cost.

Kitchen and bathroom fittings: If your extension includes a new kitchen or bathroom, fittings can add £8,000-£25,000+ depending on quality.

Location: Labour costs in London and the South East run 30-40% higher than in the Midlands and North. A £50,000 extension in Mansfield might cost £70,000 in Surrey for identical work.

What Types of Single Storey Extension Can You Build?

Rear Extensions

The most popular choice. Rear extensions typically create open-plan kitchen-dining-living spaces that transform how families use their homes. They work particularly well when you add bi-fold or sliding doors connecting to the garden.

Average cost: £25,000-£40,000 for a standard rear extension

Best for: Kitchen expansions, open-plan living, connecting indoor and outdoor space

Side Return Extensions

Ideal for terraced and semi-detached houses with unused alleyway space down the side. Side returns are typically narrower but can dramatically improve flow between rooms.

Average cost: £15,000-£25,000 for a side return

Best for: Expanding narrow kitchens, adding utility rooms, creating better circulation

Wraparound Extensions

Combines rear and side space to create substantial additional floor area. These need more structural work and rarely qualify for permitted development, so expect planning permission costs and longer timescales.

Average cost: £50,000-£90,000 for a wraparound extension

Best for: Maximum ground floor space, creating large open-plan areas, properties with both rear and side space available

Kitchen Extensions

The most common single storey extension type. Purpose-built kitchen extensions transform the heart of your home and consistently deliver strong value increases because buyers view modern kitchens as essential.

Average cost: £30,000-£65,000 depending on size and specification

Best for: Families wanting modern open-plan kitchen-diners, properties with outdated kitchens, creating entertaining spaces

Do Single Storey Extensions Add Value to Your Property?

Yes, but the amount depends on what you build and how you do it. Recent UK research shows home extensions can add anywhere from 5% to 20% to property value, with single storey extensions typically delivering 10-15% increases.

According to property data, the average extension delivers a 71% return on investment, generating an average profit of £14,000. A well-executed kitchen extension can add 10-15% to property value because buyers see modern kitchens as essential rather than optional.

The Numbers on Value Increases

Based on Nationwide research and property market data:

  • Extra living space: Adding 15 square metres to a £300,000 property can add approximately £21,000 in value
  • Kitchen extensions specifically: 10-15% property value increase
  • Open-plan living spaces: Higher returns than simple room additions because buyers actively seek these layouts
  • Quality matters: Well-executed extensions with good materials deliver better returns than budget builds

In our local market across Mansfield, Nottinghamshire, South Yorkshire and Derbyshire, we see strong returns on practical family extensions that solve real problems. Single storey extensions work best when they create high-demand spaces like kitchen-diners or family rooms with garden access.

The key insight from our projects is that success depends on building the right features for your local market and executing them properly.

Do You Need Planning Permission for a Single Storey Extension?

Many single storey extensions fall under permitted development rights, meaning you can build without planning permission. However, the rules have specific limits you must follow.

Permitted Development Rules for Single Storey Extensions

You can build without planning permission if:

For rear extensions:

  • Extension does not exceed 3 metres beyond the rear wall (terraced/semi-detached) or 4 metres (detached)
  • Maximum height of 4 metres for pitched roofs, 3 metres for flat roofs
  • Eaves height not exceeding 3 metres if within 2 metres of a boundary
  • Materials similar in appearance to the existing house

For side extensions:

  • Single storey only, maximum 4 metres in height
  • Cannot exceed 50% of the width of the original property
  • Not closer to the highway than any existing wall

General restrictions:

  • Extensions cannot cover more than 50% of the land around your original house (including any existing extensions)
  • Cannot extend forward of the principal elevation or side elevation facing a highway
  • No balconies, verandas or raised platforms

Larger Extensions Under Prior Approval

You can build larger rear extensions (up to 6 metres for terraced/semi-detached, 8 metres for detached) under permitted development if you go through a prior approval process. This involves notifying neighbours and getting council approval, but it’s faster and simpler than full planning permission.

When You Definitely Need Planning Permission

Permitted development does not apply if:

  • Your property is a flat, maisonette or house above a basement flat
  • Your property is listed or in a conservation area, national park, Area of Outstanding Natural Beauty or World Heritage Site
  • Previous extensions have already used your permitted development allowance
  • Your extension exceeds the permitted development limits
  • You want to build a wraparound extension
  • Article 4 directions have removed permitted development rights in your area

Planning permission costs £528 and typically takes 8-12 weeks to be decided. Budget an extra £800-£1,600 for an architect to prepare your planning drawings.

At Rosebrick Developments, we’ll advise you on whether your project qualifies for permitted development or needs planning permission, and we’ll handle the application process if required.

What Are the Real Drawbacks of Single Storey Extensions?

We like to be honest about the downsides. Here are the genuine issues to consider:

You Lose Garden Space

This is the biggest trade-off. A 30 square metre extension takes 30 square metres from your garden. For properties with small gardens, this can significantly reduce outdoor space your family uses.

If you have children who play outside or you love gardening and entertaining outdoors, think carefully about how much garden you can afford to lose. Some families later regret sacrificing too much outdoor space for indoor space they use less than expected.

Temporary Disruption During Building

There will be noise, dust and mess during construction. Most single storey extensions take 2-4 months to build, during which you’ll have:

  • Builders on site most days
  • Limited or no access to part of your home
  • Noise from groundwork, bricklaying and other construction
  • Dust getting into your house despite best efforts
  • Skips and materials taking parking spaces

We work quickly, clean up daily and keep you informed throughout. Most homeowners say the disruption is manageable and worth it for the end result, but it’s not nothing.

Not Always the Best Value Per Square Metre

If you need multiple rooms or substantial extra space, a double storey extension often delivers better value per square metre. You’re getting twice the space whilst sharing foundation and roof costs.

A single storey extension makes sense when you specifically need ground floor space or your property layout doesn’t suit going up. But if you need bedrooms or bathrooms, double storey deserves serious consideration.

Reduces Natural Light for Existing Rooms

Extending outwards can reduce natural light in the rooms your extension attaches to, particularly if you’re building where windows currently exist. This effect is worse for side extensions.

You can offset this by incorporating roof lights, large windows in the extension and designing carefully to maintain light flow. But it’s something to plan for rather than discover after building.

May Not Suit Your Property Long-Term

If you later decide you need more bedrooms or want to extend upwards, having already built a single storey extension can complicate things. The existing extension foundations may not support a second storey, meaning expensive strengthening work.

Some homeowners plan ahead by having foundations built strong enough to support a future second storey, even if they’re only building single storey initially. This costs more upfront but keeps options open.

Which Features Should You Include in Your Single Storey Extension?

Bi-Fold or Sliding Doors

Large doors connecting to your garden create that crucial indoor-outdoor flow buyers love. Bi-fold doors remain popular, though sliding doors are gaining ground because they’re easier to operate and maintain.

Expect to pay £2,500-£6,000 for quality bi-fold or sliding doors depending on size and specification. This investment consistently delivers strong returns.

Roof Lights or Skylights

Natural light transforms how spaces feel. Roof lights compensate for any light lost from existing rooms and make your extension feel bigger and brighter.

Budget £500-£1,500 per roof light installed. Velux-style roof windows cost less than flat roof lights, but both work well.

Quality Insulation and Glazing

Modern buyers expect energy-efficient homes. Good insulation (walls, floor and roof) and quality double or triple glazing not only feel better but command higher prices.

This isn’t where you save money. The cost difference between adequate and excellent insulation is small compared to the lifetime energy savings and better sale value.

Underfloor Heating

Particularly popular in kitchen extensions, underfloor heating creates comfortable, even warmth without radiators taking wall space. It works brilliantly with tiled floors.

Costs approximately £75-£100 per square metre installed. Many buyers specifically look for underfloor heating in extensions.

Adequate Storage

Built-in storage solutions make your extension more valuable than empty space. Consider built-in cupboards, pantry space or utility areas depending on your extension type.

Well-planned storage costs little extra during construction but adds disproportionate value.

Quality Finishes Throughout

Don’t scrimp on finishes. Buyers notice flooring, worktops, lighting and fixtures. Mid-range quality finishes deliver far better returns than budget options, whilst ultra-premium finishes don’t necessarily pay back their cost.

The sweet spot is good quality materials that look and feel substantial without extreme prices.

How Long Does a Single Storey Extension Take to Build?

From start to finish, expect:

Design and planning: 2-4 months

  • Initial consultations and design: 2-4 weeks
  • Planning permission (if required): 8-12 weeks
  • Building regulations approval: 4-6 weeks
  • These stages often overlap

Construction: 2-4 months

  • Foundations and groundwork: 1-2 weeks
  • Building to watertight: 4-6 weeks
  • First fix (electrics, plumbing, plastering): 2-3 weeks
  • Second fix and finishing: 2-3 weeks

Total project timeline is typically 4-8 months from initial design to completion. Projects requiring planning permission take longer than permitted development projects.

Weather can delay groundwork and roofing stages. Supply chain issues occasionally delay specific materials, though this has improved since 2022-2023.

At Rosebrick Developments, we give you a clear timeline before work starts and keep you updated on progress throughout.

Should You Build a Single Storey Extension or Move House?

The numbers often favour extending:

Moving house costs:

  • Estate agent fees: 1-3% of sale price
  • Solicitor fees: £1,000-£2,000
  • Stamp duty: 0-12% of purchase price depending on value
  • Removal costs: £500-£1,500
  • Survey and mortgage costs: £1,000-£2,000

For a £300,000 property, moving costs easily reach £15,000-£25,000 even if you’re buying something similar. Move to a significantly bigger property and costs increase further.

Extension advantages:

  • Stay in your preferred location
  • Keep your children in existing schools
  • Maintain your neighbourhood connections
  • Avoid stamp duty and transaction costs
  • Create exactly the space you want

When moving makes more sense:

  • You need substantially more space than an extension can provide
  • Your property has already maximised its potential
  • Location no longer suits your needs
  • Local property prices create ceiling effects limiting extension value returns

The Rosebrick Approach to Single Storey Extensions

At Rosebrick Developments, we’ve been building single storey extensions across Mansfield, Nottinghamshire, South Yorkshire and Derbyshire since 2014. Our experience from hundreds of projects shows clear patterns in what works.

The best single storey extensions we build are those that:

  • Solve genuine family needs rather than just adding space
  • Use quality materials that match or enhance the existing property
  • Integrate seamlessly with your home’s character
  • Include practical features like good lighting and storage
  • Connect well with gardens and outdoor spaces
  • Balance current needs with future resale value

Among builders in Mansfield, we understand what buyers in our region value. Kitchen extensions creating proper family spaces consistently outperform simple room additions. Extensions with good natural light and garden connections command premium prices. Quality finishes matter more than size alone.

As experienced Mansfield builders, our design and build approach means we plan your extension for both your family’s needs and maximum property value. We’ll advise on layouts, specifications and features that work best for properties in your area.

Making the Right Choice for Your Property

The best single storey extension comes from understanding your local market, building quality spaces that solve real problems, and avoiding expensive mistakes that reduce returns.

Don’t just copy what neighbours have done. Think about what your family genuinely needs and what buyers in your area actually want. Sometimes a £45,000 well-designed extension delivers better returns than a £70,000 over-specified one.

Whether you’re planning a kitchen extension, side return or wraparound addition, the fundamentals matter: good design, quality construction, and features that work for real family life.

Consider the trade-offs honestly. If losing garden space will genuinely affect your family’s happiness, maybe a loft conversion makes more sense. If you need bedrooms rather than ground floor space, a double storey extension might deliver better value despite higher costs.

Ready to Start Your Single Storey Extension?

At Rosebrick Developments, we offer:

  • Full design and build service from concept to completion
  • Help with planning permissions and building regulations
  • Honest advice on what works for your property and budget
  • Experienced, professional team who respect your home
  • Clear pricing and realistic timelines
  • Quality workmanship that lasts

We don’t do pushy sales. Just straight answers, fair pricing and builds you’ll be proud of.

If you’re in Derbyshire, South Yorkshire, Mansfield or the local Nottinghamshire areas and considering a single storey extension, let’s chat about what’s possible for your property.

Get a free, no-obligation proposal from Rosebrick Developments today. Call us or fill out our contact form and we’ll get back to you shortly.